ActiveMQ启动过程详解

JMS(ActiveMQ) PTP和PUB/SUB模式实例:http://donald-draper.iteye.com/blog/2347445
ActiveMQ连接工厂、连接详解:http://donald-draper.iteye.com/admin/blogs/2348070
ActiveMQ会话初始化:http://donald-draper.iteye.com/admin/blogs/2348341
ActiveMQ生产者:http://donald-draper.iteye.com/blog/2348381
ActiveMQ消费者:http://donald-draper.iteye.com/admin/blogs/2348389


[activemq@zabbix bin]$ more activemq
...
配置Active HOME,BASE,OPTS,CONF,JAVA_HOME&JAVA_CMD路径,
...
//执行jar包
invokeJar(){
   PIDFILE="$1"
   TASK_TODO="$2"
   RET="1"

   if [ ! -f "${ACTIVEMQ_HOME}/bin/activemq.jar" ];then
    echo "ERROR: '${ACTIVEMQ_HOME}/bin/activemq.jar' does not exist, define ACTIVEMQ_HOME in the config"
    exit 1
   fi
   #执行active jar包
   # Execute java binary
   if [ -n "$TASK_TODO" ] && [ "$TASK_TODO" != "stop" ];then
      $EXEC_OPTION $DOIT_PREFIX "\"$JAVACMD\" $ACTIVEMQ_OPTS $ACTIVEMQ_DEBUG_OPTS \
              -Dactivemq.classpath=\"${ACTIVEMQ_CLASSPATH}\" \
              -Dactivemq.home=\"${ACTIVEMQ_HOME}\" \
              -Dactivemq.base=\"${ACTIVEMQ_BASE}\" \
              -Dactivemq.conf=\"${ACTIVEMQ_CONF}\" \
              -Dactivemq.data=\"${ACTIVEMQ_DATA}\" \
              $ACTIVEMQ_CYGWIN \
              -jar \"${ACTIVEMQ_HOME}/bin/activemq.jar\" $COMMANDLINE_ARGS >/dev/null 2>&1 &
              RET=\"\$?\"; APID=\"\$!\";
              echo \$APID > "${PIDFILE}";
              echo \"INFO: pidfile created : '${PIDFILE}' (pid '\$APID')\";exit \$RET" $DOIT_POSTFIX
      RET="$?"
   
#./activemq start 启动Broker
invoke_start(){
    if ( checkRunning );then
      PID="`cat $ACTIVEMQ_PIDFILE`"
      echo "INFO: Process with pid '$PID' is already running"
      exit 0
    fi

    ACTIVEMQ_OPTS="$ACTIVEMQ_OPTS $ACTIVEMQ_SUNJMX_START $ACTIVEMQ_SSL_OPTS -Djava.awt.headless=true -Djava.io.tmpdir=\"${ACTIVEMQ_TMP}\""

    echo "INFO: Starting - inspect logfiles specified in logging.properties and log4j.properties to get details"
    invokeJar "$ACTIVEMQ_PIDFILE" start
    exit "$?"
}
....
[activemq@zabbix bin]$ ls
activemq  activemq-diag  activemq.jar  env  linux-x86-32  linux-x86-64  macosx  wrapper.jar
[activemq@zabbix bin]$ 

执行以下命令,
jar -xvf activemq.jar

可以看到,activemq jar包中有一个类为Main,这就是active的启动入口
package org.apache.activemq.console;
public class Main
{
    //shell命令任务class
    public static final String TASK_DEFAULT_CLASS = "org.apache.activemq.console.command.ShellCommand";
    private static boolean useDefExt = true;
    private File activeMQHome;//MQ家目录
    private File activeMQBase;
    private ClassLoader classLoader;//类加载器
    //activeMQ 扩展目录
    private final Set extensions = new LinkedHashSet();
    //activeMQ 类加载路径
    private final Set activeMQClassPath = new LinkedHashSet();

}
    public Main()
    {
    }
    public static void main(String args[]){
        //从洗通获取java io临时目录,没有则创建
        File tmpdir = new File(System.getProperty("java.io.tmpdir"));
        if(!tmpdir.exists())
            tmpdir.mkdirs();
        Main app = new Main();
        List tokens = new LinkedList(Arrays.asList(args));
	//解析扩展
        app.parseExtensions(tokens);
	//获取配置
        File confDir = app.getActiveMQConfig();
	//将配置文件添加到ClassPath
        app.addClassPath(confDir);
        if(useDefExt && app.canUseExtdir())
        {
            boolean baseIsHome = app.getActiveMQBase().equals(app.getActiveMQHome());
            //创建lib目录
	    File baseLibDir = new File(app.getActiveMQBase(), "lib");
            File homeLibDir = new File(app.getActiveMQHome(), "lib");
            if(!baseIsHome)
                app.addExtensionDirectory(baseLibDir);
            app.addExtensionDirectory(homeLibDir);
	    //创建lib下的camel,optional,web,extra目录
            if(!baseIsHome)
            {
                app.addExtensionDirectory(new File(baseLibDir, "camel"));
                app.addExtensionDirectory(new File(baseLibDir, "optional"));
                app.addExtensionDirectory(new File(baseLibDir, "web"));
                app.addExtensionDirectory(new File(baseLibDir, "extra"));
            }
            app.addExtensionDirectory(new File(homeLibDir, "camel"));
            app.addExtensionDirectory(new File(homeLibDir, "optional"));
            app.addExtensionDirectory(new File(homeLibDir, "web"));
            app.addExtensionDirectory(new File(homeLibDir, "extra"));
        }
	//从系统获取activemq.classpath,添加到
        app.addClassPathList(System.getProperty("activemq.classpath"));
        try
        {
	    //启动broker
            int ret = app.runTaskClass(tokens);
            System.exit(ret);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println((new StringBuilder()).append("Could not load class: ").append(e.getMessage()).toString());
            try
            {
                ClassLoader cl = app.getClassLoader();
                if(cl != null)
                {
                    System.out.println("Class loader setup: ");
                    printClassLoaderTree(cl);
                }
            }
            catch(MalformedURLException malformedurlexception) { }
            System.exit(1);
        }
        catch(Throwable e)
        {
            System.out.println((new StringBuilder()).append("Failed to execute main task. Reason: ").append(e).toString());
            System.exit(1);
        }
    }

1.解析扩展
app.parseExtensions(tokens);


public void parseExtensions(List tokens)
    {
        if(tokens.isEmpty())
            return;
        int count = tokens.size();
        for(int i = 0; i < count;)
        {
            String token = (String)tokens.get(i);
            if(token.equals("--extdir"))
            {
                count--;
                tokens.remove(i);
                    if(!extDir.isDirectory())
                    {
                        System.out.println((new StringBuilder()).append("Extension directory specified is not valid directory: ").append(extDir).toString());
                        System.out.println("Ignoring extension directory option.");
                    } else
                    {
		        //添加拓展目录
                        addExtensionDirectory(extDir);
                    }
}

//添加拓展目录
    public void addExtensionDirectory(File directory)
    {
        extensions.add(directory);
    }

从上可以看出,解析拓展目录配置项,并将扩展目录添加到拓展集合中
2.获取配置
File confDir = app.getActiveMQConfig();
 public File getActiveMQConfig()
    {
        File activeMQConfig = null;
        if(System.getProperty("activemq.conf") != null)
        {
	    //从系统获取activemq.conf,如果不为空,则创建配置文件
            activeMQConfig = new File(System.getProperty("activemq.conf"));
        } else
        {
            activeMQConfig = new File((new StringBuilder()).append(getActiveMQBase()).append("/conf").toString());
            System.setProperty("activemq.conf", activeMQConfig.getAbsolutePath());
        }
        return activeMQConfig;
    }


3.将配置文件添加到ClassPath
app.addClassPath(confDir);
  public void addClassPath(File classpath)
    {
        activeMQClassPath.add(classpath);
    }

将配置文件添加到ClassPath集合中
4.
boolean baseIsHome = app.getActiveMQBase().equals(app.getActiveMQHome());
//创建lib目录
 File baseLibDir = new File(app.getActiveMQBase(), "lib");
 File homeLibDir = new File(app.getActiveMQHome(), "lib");
 if(!baseIsHome)
     app.addExtensionDirectory(baseLibDir);
 app.addExtensionDirectory(homeLibDir);
 //创建lib下的camel,optional,web,extra目录
 app.addExtensionDirectory(new File(homeLibDir, "camel"));
 app.addExtensionDirectory(new File(homeLibDir, "optional"));
 app.addExtensionDirectory(new File(homeLibDir, "web"));
 app.addExtensionDirectory(new File(homeLibDir, "extra"));


将lib扩展目录添加到扩展目录集合中

5.
从系统获取activemq.classpath,添加到ClassPath集合中
app.addClassPathList(System.getProperty("activemq.classpath"));


6.
启动broker
 int ret = app.runTaskClass(tokens);



public int runTaskClass(List tokens)
        throws Throwable
    {
        ClassLoader cl;
	//获取java版本及home目录
        StringBuilder buffer = new StringBuilder();
        buffer.append(System.getProperty("java.vendor"));
        buffer.append(" ");
        buffer.append(System.getProperty("java.version"));
        buffer.append(" ");
        buffer.append(System.getProperty("java.home"));
        System.out.println((new StringBuilder()).append("Java Runtime: ").append(buffer.toString()).toString());
        buffer = new StringBuilder();
	//获取java运行时环境的内存状况
        buffer.append("current=");
        buffer.append(Runtime.getRuntime().totalMemory() / 1024L);
        buffer.append("k  free=");
        buffer.append(Runtime.getRuntime().freeMemory() / 1024L);
        buffer.append("k  max=");
        buffer.append(Runtime.getRuntime().maxMemory() / 1024L);
        buffer.append("k");
        System.out.println((new StringBuilder()).append("  Heap sizes: ").append(buffer.toString()).toString());
        List jvmArgs = ManagementFactory.getRuntimeMXBean().getInputArguments();
        buffer = new StringBuilder();
        Object arg;
        for(Iterator i$ = jvmArgs.iterator(); i$.hasNext(); buffer.append(" ").append(arg))
            arg = i$.next();
        //配置MQ扩展目录,家目录,配置文件以及数据目录
        System.out.println((new StringBuilder()).append("    JVM args:").append(buffer.toString()).toString());
        System.out.println((new StringBuilder()).append("Extensions classpath:\n  ").append(getExtensionDirForLogging()).toString());
        System.out.println((new StringBuilder()).append("ACTIVEMQ_HOME: ").append(getActiveMQHome()).toString());
        System.out.println((new StringBuilder()).append("ACTIVEMQ_BASE: ").append(getActiveMQBase()).toString());
        System.out.println((new StringBuilder()).append("ACTIVEMQ_CONF: ").append(getActiveMQConfig()).toString());
        System.out.println((new StringBuilder()).append("ACTIVEMQ_DATA: ").append(getActiveMQDataDir()).toString());
        //获取类加载器
	cl = getClassLoader();
        Thread.currentThread().setContextClassLoader(cl);
        String args[];
        Class task;
        Method runTask;
        args = (String[])tokens.toArray(new String[tokens.size()]);
	//加载ShellCommand类
        task = cl.loadClass("org.apache.activemq.console.command.ShellCommand");
	//获取ShellCommand的main方法
        runTask = task.getMethod("main", new Class[] {
            [Ljava/lang/String;, java/io/InputStream, java/io/PrintStream
        });
	//调用ShellCommand的
        return ((Integer)runTask.invoke(task.newInstance(), new Object[] {
            args, System.in, System.out
        })).intValue();
        InvocationTargetException e;
        e;
        throw e.getCause();
    }
   //获取加载类
    public ClassLoader getClassLoader()
        throws MalformedURLException
    {
        if(classLoader == null)
        {
            classLoader = org/apache/activemq/console/Main.getClassLoader();
            if(!extensions.isEmpty() || !activeMQClassPath.isEmpty())
            {
                ArrayList urls = new ArrayList();
                Iterator iter;
                File dir;
                for(iter = activeMQClassPath.iterator(); iter.hasNext(); urls.add(dir.toURI().toURL()))
                    dir = (File)iter.next();

                iter = extensions.iterator();
                do
                {
                    if(!iter.hasNext())
                        break;
                    File dir = (File)iter.next();
                    if(dir.isDirectory())
                    {
                        File files[] = dir.listFiles();
                        if(files != null)
                        {
                            Arrays.sort(files, new Comparator() {

                                public int compare(File f1, File f2)
                                {
                                    return f1.getName().compareTo(f2.getName());
                                }

                                public volatile int compare(Object obj, Object obj1)
                                {
                                    return compare((File)obj, (File)obj1);
                                }

                                final Main this$0;

            
            {
                this$0 = Main.this;
                super();
            }
                            });
                            int j = 0;
                            while(j < files.length) 
                            {
                                if(files[j].getName().endsWith(".zip") || files[j].getName().endsWith(".jar"))
                                    urls.add(files[j].toURI().toURL());
                                j++;
                            }
                        }
                    }
                } while(true);
                URL u[] = new URL[urls.size()];
                urls.toArray(u);
                classLoader = new URLClassLoader(u, classLoader);
            }
	    //设置当前线程类加载器
            Thread.currentThread().setContextClassLoader(classLoader);
        }
        return classLoader;
    }

我们来看ShellCommand类,及其main方法

public class ShellCommand extends AbstractCommand
{
    private boolean interactive;
    private String helpFile[];
    public ShellCommand()
    {
        this(false);
    }
     public ShellCommand(boolean interactive)
    {
        this.interactive = interactive;
        ArrayList help = new ArrayList();
        help.addAll(Arrays.asList(new String[] {
            interactive ? "Usage: [task] [task-options] [task data]" : "Usage: Main [--extdir <dir>] [task] [task-options] [task data]", "", "Tasks:"
        }));
        ArrayList commands = getCommands();
        Collections.sort(commands, new Comparator() {

            public int compare(Command command, Command command1)
            {
                return command.getName().compareTo(command1.getName());
            }

            public volatile int compare(Object obj, Object obj1)
            {
                return compare((Command)obj, (Command)obj1);
            }

            final ShellCommand this$0;

            
            {
                this$0 = ShellCommand.this;
                super();
            }
        });
        Command command;
        for(Iterator i$ = commands.iterator(); i$.hasNext(); help.add(String.format("    %-24s - %s", new Object[] {
    command.getName(), command.getOneLineDescription()
})))
            command = (Command)i$.next();

        help.addAll(Arrays.asList(new String[] {
            "", "Task Options (Options specific to each task):", "    --extdir <dir>  - Add the jar files in the directory to the classpath.", "    --version       - Display the version information.", (new StringBuilder()).append("    -h,-?,--help    - Display this help information. To display task specific help, use ").append(interactive ? "" : "Main ").append("[task] -h,-?,--help").toString(), "", "Task Data:", "    - Information needed by each specific task.", "", "JMX system property options:", 
            "    -Dactivemq.jmx.url=<jmx service uri> (default is: 'service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi')", "    -Dactivemq.jmx.user=<user name>", "    -Dactivemq.jmx.password=<password>", ""
        }));
	//将扩展目录,lib目录添加到辅助文件集合
        helpFile = (String[])help.toArray(new String[help.size()]);
    }
}

再看main方法:
public static int main(String args[], InputStream in, PrintStream out)
    {
        CommandContext context;
        List tokens;
        ShellCommand main;
	//创建命令上下文
        context = new CommandContext();
        context.setFormatter(new CommandShellOutputFormatter(out));
        tokens = new ArrayList(Arrays.asList(args));
        main = new ShellCommand();
        main.setCommandContext(context);
        //执行启动broker命令
        main.execute(tokens);
        return 0;
        Exception e;
        e;
        context.printException(e);
        return 1;
    }

来看执行启动broker命令
main.execute(tokens);

//AbstractCommand
 public void execute(List tokens)
        throws Exception
    {
        //解析activemq 命令参数
        parseOptions(tokens);
	//打印帮助命令
        if(isPrintHelp)
            printHelp();
        else
	//打印版本
        if(isPrintVersion)
            context.printVersion(ActiveMQConnectionMetaData.PROVIDER_VERSION);
        else
	    //启动broker
            runTask(tokens);
    }
  //解析参数
 protected void parseOptions(List tokens)
        throws Exception
    {
        while(!tokens.isEmpty()) 
        {
            String token = (String)tokens.remove(0);
            if(token.startsWith("-"))
            {
	        //以“-”开头,则为配置项,处理参数配置项
                handleOption(token, tokens);
            } else
            {
	        //否则为命令
                tokens.add(0, token);
                return;
            }
        }
    }

    protected void handleOption(String token, List tokens)
        throws Exception
    {
        isPrintHelp = false;
        isPrintVersion = false;
        if(token.equals("-h") || token.equals("-?") || token.equals("--help"))
        {
	    //帮助信息,清除tokens
            isPrintHelp = true;
            tokens.clear();
        } else
        if(token.equals("--version"))
        {
	    //打印版本
            isPrintVersion = true;
            tokens.clear();
        } else
        if(token.startsWith("-D"))
        {
	    //系统参数
            String key = token.substring(2);
            String value = "";
            int pos = key.indexOf("=");
            if(pos >= 0)
            {
                value = key.substring(pos + 1);
                key = key.substring(0, pos);
            }
            System.setProperty(key, value);
        } else
        {
	   //扩展配置型
            if(token.startsWith("--"))
            {
                String prop = token.substring(2);
                if(tokens.isEmpty() || ((String)tokens.get(0)).startsWith("-"))
                    context.print((new StringBuilder()).append("Property '").append(prop).append("' is not specified!").toString());
                else
                if(IntrospectionSupport.setProperty(this, prop, tokens.remove(0)))
                    return;
            }
            context.printInfo((new StringBuilder()).append("Unrecognized option: ").append(token).toString());
            isPrintHelp = true;
        }
    }

回到启动broker中
//打印帮助命令
if(isPrintHelp)
     printHelp();

//ShellCommand
protected void printHelp()
    {
        context.printHelp(helpFile);
    }

CommandContext通过CommandShellOutputFormatter打印帮助文档
//CommandShellOutputFormatter
public class CommandShellOutputFormatter
    implements OutputFormatter
{
   private OutputStream outputStream;
   private PrintStream out;
 public void printHelp(String helpMsgs[])
    {
        for(int i = 0; i < helpMsgs.length; i++)
            out.println(helpMsgs[i]);

        out.println();
    }
}



从上面可以看当activemq的参数为帮助信息或版本信息,则打印相关信息,否则启动broker
回到启动命令
//启动broker
runTask(tokens);



//ShellCommand
protected void runTask(List tokens)
        throws Exception
    {
        if(tokens.size() > 0)
        {
            Command command = null;
            String taskToken = (String)tokens.remove(0);
            Iterator i$ = getCommands().iterator();
            do
            {
                if(!i$.hasNext())
                    break;
                Command c = (Command)i$.next();
                if(!taskToken.equals(c.getName()))
                    continue;
                command = c;
                break;
            } while(true);
            if(command == null)
                if(taskToken.equals("help"))
                    printHelp();
                else
                    printHelp();
            if(command != null)
            {
                command.setCommandContext(context);
		//执行命令
                command.execute(tokens);
            }
        } else
        {
            printHelp();
        }
    }

我们来看start命令
public class StartCommand extends AbstractCommand
{
    //配置文件
    public static final String DEFAULT_CONFIG_URI = "xbean:activemq.xml";
    //帮助文档
    protected String helpFile[] = {
        "Task Usage: Main start [start-options] [uri]", "Description: Creates and starts a broker using a configuration file, or a broker URI.", "", "Start Options:", "    -D<name>=<value>      Define a system property.", "    --version             Display the version information.", "    -h,-?,--help          Display the start broker help information.", "", "URI:", "", 
        "    XBean based broker configuration:", "", "        Example: Main xbean:file:activemq.xml", "            Loads the xbean configuration file from the current working directory", "        Example: Main xbean:activemq.xml", "            Loads the xbean configuration file from the classpath", "", "    URI Parameter based broker configuration:", "", "        Example: Main broker:(tcp://localhost:61616, tcp://localhost:5000)?useJmx=true", 
        "            Configures the broker with 2 transport connectors and jmx enabled", "        Example: Main broker:(tcp://localhost:61616, network:tcp://localhost:5000)?persistent=false", "            Configures the broker with 1 transport connector, and 1 network connector and persistence disabled", ""
    };
}


//StartCommand

 protected void runTask(List brokerURIs)
        throws Exception
    {
        do
        {
            final BrokerService broker;
            try
            {
                URI configURI;
                if(brokerURIs.isEmpty())
                    configURI = new URI("xbean:activemq.xml");
                else
                    configURI = new URI((String)brokerURIs.get(0));
                System.out.println((new StringBuilder()).append("Loading message broker from: ").append(configURI).toString());
                //BrokerFactory工厂根据配置文件创建Broker服务
		broker = BrokerFactory.createBroker(configURI);
		//启动Broker
                broker.start();
            }
            catch(Exception e)
            {
                context.printException(new RuntimeException((new StringBuilder()).append("Failed to execute start task. Reason: ").append(e).toString(), e));
                throw e;
            }
            if(!broker.waitUntilStarted())
                throw new Exception(broker.getStartException());

            final CountDownLatch shutdownLatch = new CountDownLatch(1);
	    //添加停止broker的JVM回调挂钩
            Thread jvmShutdownHook = new Thread() {

                public void run()
                {
                    try
                    {
                        broker.stop();
                    }
                    catch(Exception exception) { }
                }

                final BrokerService val$broker;
                final StartCommand this$0;

            
            {
                this$0 = StartCommand.this;
                broker = brokerservice;
                super();
            }
            };
	    //将停止broker的JVM回调挂钩添加到运行时环境
            Runtime.getRuntime().addShutdownHook(jvmShutdownHook);
            broker.addShutdownHook(new Runnable() {

                public void run()
                {
                    shutdownLatch.countDown();
                }

                final CountDownLatch val$shutdownLatch;
                final StartCommand this$0;

            
            {
                this$0 = StartCommand.this;
                shutdownLatch = countdownlatch;
                super();
            }
            });
	    //等待停止broker信号shutdownLatch
            shutdownLatch.await();
            try
            {
                Runtime.getRuntime().removeShutdownHook(jvmShutdownHook);
            }
            catch(Throwable throwable) { }
            if(broker.isRestartRequested())
                System.out.println("Restarting broker");
            else
                return;
        } while(true);
    }

来看BrokerFactory工厂根据配置文件创建Broker服务
broker = BrokerFactory.createBroker(configURI);


public static BrokerService createBroker(URI brokerURI)
        throws Exception
    {
        return createBroker(brokerURI, false);
    }
    public static BrokerService createBroker(URI brokerURI, boolean startBroker)
        throws Exception
    {
        if(brokerURI.getScheme() == null)
            throw new IllegalArgumentException((new StringBuilder()).append("Invalid broker URI, no scheme specified: ").append(brokerURI).toString());
        //a.创建broker工厂处理handler
	BrokerFactoryHandler handler = createBrokerFactoryHandler(brokerURI.getScheme());
	//b.由Handler创建BrokerService
        BrokerService broker = handler.createBroker(brokerURI);
        if(startBroker)
            broker.start();
        return broker;
    }

a.创建broker工厂处理handler
BrokerFactoryHandler handler = createBrokerFactoryHandler(brokerURI.getScheme());
有上面configURI = new URI("xbean:activemq.xml"),activeMQ将配置文件,放在JMX中管理,
协议为Xbean
public final class BrokerFactory
{
   //看到这个是不是很熟悉,根据协议机制,加载BROKER_FACTORY
   private static final FactoryFinder BROKER_FACTORY_HANDLER_FINDER = new FactoryFinder("META-INF/services/org/apache/activemq/broker/");
   private static final ThreadLocal START_DEFAULT = new ThreadLocal();
   //创建broker工厂handler,
   public static BrokerFactoryHandler createBrokerFactoryHandler(String type)
        throws IOException
    {
        //这种模式,前面已经说过,加载META-INF/services/org/apache/activemq/broker/
	//文件夹下xbean文件中class属性对应的broker工厂类
        return (BrokerFactoryHandler)BROKER_FACTORY_HANDLER_FINDER.newInstance(type);
    }
}

xbean文件
class=org.apache.activemq.xbean.XBeanBrokerFactory


b.由Handler创建BrokerService
BrokerService broker = handler.createBroker(brokerURI);


//XBeanBrokerFactory

public class XBeanBrokerFactory
    implements BrokerFactoryHandler
{
   private boolean validate;
    static 
    {
        PropertyEditorManager.registerEditor(java/net/URI, org/apache/xbean/spring/context/impl/URIEditor);
    }
}

//XBeanBrokerFactory
public BrokerService createBroker(URI config)
        throws Exception
    {
        String uri = config.getSchemeSpecificPart();
        if(uri.lastIndexOf('?') != -1)
        {
            IntrospectionSupport.setProperties(this, URISupport.parseQuery(uri));
            uri = uri.substring(0, uri.lastIndexOf('?'));
        }
	//创建上下文
        ApplicationContext context = createApplicationContext(uri);
        BrokerService broker = null;
        try
        {
	    //从上下文中获取broker属性
            broker = (BrokerService)context.getBean("broker");
        }
        catch(BeansException beansexception) { }
        if(broker == null)
        {
            String names[] = context.getBeanNamesForType(org/apache/activemq/broker/BrokerService);
            int i = 0;
            do
            {
                if(i >= names.length)
                    break;
                String name = names[i];
                broker = (BrokerService)context.getBean(name);
                if(broker != null)
                    break;
                i++;
            } while(true);
        }
        if(broker == null)
        {
            throw new IllegalArgumentException((new StringBuilder()).append("The configuration has no BrokerService instance for resource: ").append(config).toString());
        } else
        {
            SpringBrokerContext springBrokerContext = new SpringBrokerContext();
            springBrokerContext.setApplicationContext(context);
            springBrokerContext.setConfigurationUrl(uri);
            broker.setBrokerContext(springBrokerContext);
            return broker;
        }
    }

//创建应用上下文,通Spring的机制
 protected ApplicationContext createApplicationContext(String uri)
        throws MalformedURLException
    {
        Resource resource;
        resource = Utils.resourceFromString(uri);
        LOG.debug((new StringBuilder()).append("Using ").append(resource).append(" from ").append(uri).toString());
        return new ResourceXmlApplicationContext(resource) {

            protected void initBeanDefinitionReader(XmlBeanDefinitionReader reader)
            {
                reader.setValidating(isValidate());
            }
             //XML Broker工厂
            final XBeanBrokerFactory this$0;

            
            {
                this$0 = XBeanBrokerFactory.this;
                super(x0);
            }
        };
        FatalBeanException errorToLog;
        errorToLog;
        LOG.error((new StringBuilder()).append("Failed to load: ").append(resource).append(", reason: ").append(errorToLog.getLocalizedMessage()).toString(), errorToLog);
        throw errorToLog;
    }

贴上activemq.xml broker配置片段,以便理解
 
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}">

        <destinationPolicy>
            <policyMap>
              <policyEntries>
                <policyEntry topic=">" >
                    <!-- The constantPendingMessageLimitStrategy is used to prevent
                         slow topic consumers to block producers and affect other consumers
                         by limiting the number of messages that are retained
                         For more information, see:

                         http://activemq.apache.org/slow-consumer-handling.html

                    -->
                  <pendingMessageLimitStrategy>
                    <constantPendingMessageLimitStrategy limit="1000"/>
                  </pendingMessageLimitStrategy>
                </policyEntry>
              </policyEntries>
            </policyMap>
        </destinationPolicy>


        <!--
            The managementContext is used to configure how ActiveMQ is exposed in
            JMX. By default, ActiveMQ uses the MBean server that is started by
            the JVM. For more information, see:

            http://activemq.apache.org/jmx.html
        -->
        <managementContext>
            <managementContext createConnector="false"/>
        </managementContext>

        <!--
            Configure message persistence for the broker. The default persistence
            mechanism is the KahaDB store (identified by the kahaDB tag).
            For more information, see:

            http://activemq.apache.org/persistence.html
        -->
        <persistenceAdapter>
            <kahaDB directory="${activemq.data}/kahadb"/>
        </persistenceAdapter>


          <!--
            The systemUsage controls the maximum amount of space the broker will
            use before disabling caching and/or slowing down producers. For more information, see:
            http://activemq.apache.org/producer-flow-control.html
          -->
          <systemUsage>
            <systemUsage>
                <memoryUsage>
                    <memoryUsage percentOfJvmHeap="70" />
                </memoryUsage>
                <storeUsage>
                    <storeUsage limit="100 gb"/>
                </storeUsage>
                <tempUsage>
                    <tempUsage limit="50 gb"/>
                </tempUsage>
            </systemUsage>
        </systemUsage>

        <!--
            The transport connectors expose ActiveMQ over a given protocol to
            clients and other brokers. For more information, see:

            http://activemq.apache.org/configuring-transports.html
        -->
        <transportConnectors>
            <!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
            <transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
            <transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
        </transportConnectors>

        <!-- destroy the spring context on shutdown to stop jetty -->
        <shutdownHooks>
            <bean xmlns="http://www.springframework.org/schema/beans" class="org.apache.activemq.hooks.SpringContextHook" />
        </shutdownHooks>

    </broker>




//从上下文中获取broker属性
broker = (BrokerService)context.getBean("broker");

public class XBeanBrokerService extends BrokerService
{ 
  private boolean start;
  public XBeanBrokerService()
    {
        start = BrokerFactory.getStartDefault();
    }
    //在构造完之后,调用afterPropertiesSet
    private void postConstruct()
    {
        try
        {
            afterPropertiesSet();
        }
        catch(Exception ex)
        {
            throw new RuntimeException(ex);
        }
    }

    public void afterPropertiesSet()
        throws Exception
    {   
        //初始化内存使用情况
        ensureSystemUsageHasStore();
        if(shouldAutostart())
            start();
    }
    //保证内存还有空间可用
    private void ensureSystemUsageHasStore()
        throws IOException
    {
        SystemUsage usage = getSystemUsage();
        if(usage.getStoreUsage().getStore() == null)
            usage.getStoreUsage().setStore(getPersistenceAdapter());
        if(usage.getTempUsage().getStore() == null)
            usage.getTempUsage().setStore(getTempDataStore());
        if(usage.getJobSchedulerUsage().getStore() == null)
            usage.getJobSchedulerUsage().setStore(getJobSchedulerStore());
    }
}

从上可以看出XBeanBrokerFactory首先根据activemq.xml在JMX中xbean信息,通过Spring加载
应用上下文的方式解析xbean信息,然后从应用上下文中获取broker服务XBeanBrokerService

再看启动Broker
broker.start();

启动在BrokerService中
public class BrokerService
    implements Service
{
   public static final String DEFAULT_PORT = "61616";//默认端口
    public static final String LOCAL_HOST_NAME;
    public static final String BROKER_VERSION;
    public static final String DEFAULT_BROKER_NAME = "localhost";
    public static final int DEFAULT_MAX_FILE_LENGTH = 33554432;
    public static final long DEFAULT_START_TIMEOUT = 600000L;
    private static final Logger LOG;
    private static final long serialVersionUID = 7353129142305630237L;
    private boolean useJmx;//是否用JMX
    private boolean enableStatistics;//是否开启统计
    private boolean persistent;//是否持久化
    private boolean populateJMSXUserID;
    private boolean useAuthenticatedPrincipalForJMSXUserID;//JMX用户验证id
    private boolean populateUserNameInMBeans;
    private long mbeanInvocationTimeout;
    private boolean useShutdownHook;//java运行时,关闭broker,是否有Hook
    private boolean useLoggingForShutdownErrors;
    private boolean shutdownOnMasterFailure;//是否在Master宕机时,关闭broker
    private boolean shutdownOnSlaveFailure;
    private boolean waitForSlave;
    private long waitForSlaveTimeout;
    private boolean passiveSlave;
    private String brokerName;//broker名称
    private File dataDirectoryFile;//数据目录
    private File tmpDataDirectory;
    private Broker broker;
    private BrokerView adminView;
    private ManagementContext managementContext;//管理器上下文
    private ObjectName brokerObjectName;
    private TaskRunnerFactory taskRunnerFactory;//任务工厂
    private TaskRunnerFactory persistenceTaskRunnerFactory;
    private SystemUsage systemUsage;//系统内存使用情况
    private SystemUsage producerSystemUsage;//生产者内存使用情况
    private SystemUsage consumerSystemUsaage;//消费者内存使用情况
    private PersistenceAdapter persistenceAdapter;//持久化适配器
    private PersistenceAdapterFactory persistenceFactory;//持久化工厂
    protected DestinationFactory destinationFactory;//目的地工厂
    private MessageAuthorizationPolicy messageAuthorizationPolicy;//消息验证策略
    private final List transportConnectors = new CopyOnWriteArrayList();//transportConnectors
    private final List networkConnectors = new CopyOnWriteArrayList();//networkConnectors
    private final List proxyConnectors = new CopyOnWriteArrayList();
    private final List jmsConnectors = new CopyOnWriteArrayList();//jmsConnectors
    private final List services = new ArrayList();
    private transient Thread shutdownHook;//关闭broke,运行hook线程
    private String transportConnectorURIs[];//transportConnector urI
    private String networkConnectorURIs[];
    private JmsConnector jmsBridgeConnectors[];
    private boolean deleteAllMessagesOnStartup;//是否在启时,删除所有消息
    private boolean advisorySupport;
    private URI vmConnectorURI;//虚拟机URI
    private String defaultSocketURIString;
    private PolicyMap destinationPolicy;
    //Broker运行状态
    private final AtomicBoolean started = new AtomicBoolean(false);
    private final AtomicBoolean stopped = new AtomicBoolean(false);
    private final AtomicBoolean stopping = new AtomicBoolean(false);
    private BrokerPlugin plugins[];
    private boolean keepDurableSubsActive;
    private boolean useVirtualTopics;
    private boolean useMirroredQueues;
    private boolean useTempMirroredQueues;
    //brokerid
    private BrokerId brokerId;
    private volatile DestinationInterceptor destinationInterceptors[];
    private ActiveMQDestination destinations[];//消息目的地
    private PListStore tempDataStore;
    private int persistenceThreadPriority;//持久化线程优先级
    private boolean useLocalHostBrokerName;
    private final CountDownLatch stoppedLatch = new CountDownLatch(1);//关闭信号量
    private final CountDownLatch startedLatch = new CountDownLatch(1);//启动信号量
    private Broker regionBroker;
    private int producerSystemUsagePortion;
    private int consumerSystemUsagePortion;
    private boolean splitSystemUsageForProducersConsumers;
    private boolean monitorConnectionSplits;
    private int taskRunnerPriority;//任务线程优先级
    private boolean dedicatedTaskRunner;
    private boolean cacheTempDestinations;
    private int timeBeforePurgeTempDestinations;
    private final List shutdownHooks = new ArrayList();
    private boolean systemExitOnShutdown;
    private int systemExitOnShutdownExitCode;
    private SslContext sslContext;//SSL上下文
    private boolean forceStart;
    private IOExceptionHandler ioExceptionHandler;
    private boolean schedulerSupport;
    private File schedulerDirectoryFile;
    private Scheduler scheduler;//调度器
    private ThreadPoolExecutor executor;//线程执行器
    private int schedulePeriodForDestinationPurge;
    private int maxPurgedDestinationsPerSweep;
    private int schedulePeriodForDiskUsageCheck;
    private BrokerContext brokerContext;//broker上下文
    private boolean networkConnectorStartAsync;
    private boolean allowTempAutoCreationOnSend;
    private JobSchedulerStore jobSchedulerStore;//job调度存储器
    private final AtomicLong totalConnections = new AtomicLong();//连接数
    private final AtomicInteger currentConnections = new AtomicInteger();
    private long offlineDurableSubscriberTimeout;
    private long offlineDurableSubscriberTaskSchedule;
    private DestinationFilter virtualConsumerDestinationFilter;
    private final AtomicBoolean persistenceAdapterStarted = new AtomicBoolean(false);
    private Throwable startException;
    private boolean startAsync;
    private Date startDate;
    private boolean slave;
    private boolean restartAllowed;
    private boolean restartRequested;
    private boolean rejectDurableConsumers;
    private int storeOpenWireVersion;

    static 
    {
        //加载版本信息
        String version;
        LOG = LoggerFactory.getLogger(org/apache/activemq/broker/BrokerService);
        try
        {
            ClassLoader loader = org/apache/activemq/broker/BrokerService.getClassLoader();
            Class clazz = loader.loadClass("org.bouncycastle.jce.provider.BouncyCastleProvider");
            Provider bouncycastle = (Provider)clazz.newInstance();
            Security.insertProviderAt(bouncycastle, 2);
            LOG.info("Loaded the Bouncy Castle security provider.");
        }
        String localHostName = "localhost";
        try
        {
            localHostName = InetAddressUtil.getLocalHostName();
        }
        LOCAL_HOST_NAME = localHostName;
        version = null;
        InputStream in;
        in = org/apache/activemq/broker/BrokerService.getResourceAsStream("/org/apache/activemq/version.txt");
        InputStreamReader isr;
        isr = new InputStreamReader(in);
        BufferedReader reader;
        reader = new BufferedReader(isr);
        try
        {
            version = reader.readLine();
        }
        IOException ie;
        ie;
        LOG.warn("Error reading broker version ", ie);
        BROKER_VERSION = version;
    }



    public BrokerService()
    {
        useJmx = true;
        enableStatistics = true;
        persistent = true;
        mbeanInvocationTimeout = 0L;
        useShutdownHook = true;
        waitForSlaveTimeout = 600000L;
        brokerName = "localhost";
        advisorySupport = true;
        keepDurableSubsActive = true;
        useVirtualTopics = true;
        useMirroredQueues = false;
        useTempMirroredQueues = true;
        persistenceThreadPriority = 10;
        producerSystemUsagePortion = 60;
        consumerSystemUsagePortion = 40;
        monitorConnectionSplits = false;
        taskRunnerPriority = 5;
        cacheTempDestinations = false;
        timeBeforePurgeTempDestinations = 5000;
        forceStart = false;
        schedulerSupport = false;
        schedulePeriodForDestinationPurge = 0;
        maxPurgedDestinationsPerSweep = 0;
        schedulePeriodForDiskUsageCheck = 0;
        networkConnectorStartAsync = false;
        offlineDurableSubscriberTimeout = -1L;
        offlineDurableSubscriberTaskSchedule = 300000L;
        startException = null;
        startAsync = false;
        slave = true;
        restartAllowed = true;
        restartRequested = false;
        rejectDurableConsumers = false;
        storeOpenWireVersion = 11;
    }
}

从上面可以看出BrokerService的构造,主要是初始化关闭broker是否有Hook,任务线程优先级,是否允许重启,是否支出调度器,消费者生产者允许使用的内存占比。

来看启动
public void start()
        throws Exception
    {
        if(stopped.get() || !started.compareAndSet(false, true))
            return;
        stopping.set(false);
        startDate = new Date();
        MDC.put("activemq.broker", brokerName);
        if(systemExitOnShutdown && useShutdownHook)
            throw new ConfigurationException("'useShutdownHook' property cannot be be used with 'systemExitOnShutdown', please turn it off (useShutdownHook=false)");
        processHelperProperties();
        if(!isUseJmx())
            break MISSING_BLOCK_LABEL_156;
        MDC.remove("activemq.broker");
	//启动管理器上下文
        startManagementContext();
        NetworkConnector connector;
	//注册网络连接
        for(Iterator i$ = getNetworkConnectors().iterator(); i$.hasNext(); registerNetworkConnectorMBean(connector))
            connector = (NetworkConnector)i$.next();

        MDC.put("activemq.broker", brokerName);
        BrokerRegistry brokerRegistry = BrokerRegistry.getInstance();
        if(brokerRegistry.lookup(getBrokerName()) == null)
            brokerRegistry.bind(getBrokerName(), this);
	//启动适配器
        startPersistenceAdapter(startAsync);
	//启动broker
        startBroker(startAsync);
        brokerRegistry.bind(getBrokerName(), this);   
}

我们最关心的是启动broker
启动broker
startBroker(startAsync);


private void startBroker(boolean async)
        throws Exception
    {
        if(async)
            (new Thread("Broker Starting Thread") {

                public void run()
                {
                    try
                    {
                        synchronized(persistenceAdapterStarted)
                        {
                            if(!persistenceAdapterStarted.get())
                                persistenceAdapterStarted.wait();
                        }
                        doStartBroker();
                    }
                    catch(Throwable t)
                    {
                        startException = t;
                    }
                }

                final BrokerService this$0;

            
            {
                this$0 = BrokerService.this;
                super(x0);
            }
            }).start();
        else
	    //关键点
            doStartBroker();
    }
//启动broker
 private void doStartBroker()
        throws Exception
    {
        if(startException != null)
            return;
	//启动目的地
        startDestinations();
	//添加关闭hook
        addShutdownHook();
        broker = getBroker();
        brokerId = broker.getBrokerId();
        broker.start();
        if(isUseJmx())
        {
            if(getManagementContext().isCreateConnector() && !getManagementContext().isConnectorStarted())
            {
                managementContext.stop();
		//启动管理器上下文
                startManagementContext();
            }
            ManagedRegionBroker managedBroker = (ManagedRegionBroker)regionBroker;
            managedBroker.setContextBroker(broker);
            adminView.setBroker(managedBroker);
        }
        if(ioExceptionHandler == null)
            setIoExceptionHandler(new DefaultIOExceptionHandler());
        if(isUseJmx() && Log4JConfigView.isLog4JAvailable())
        {
            ObjectName objectName = BrokerMBeanSupport.createLog4JConfigViewName(getBrokerObjectName().toString());
            Log4JConfigView log4jConfigView = new Log4JConfigView();
            AnnotatedMBean.registerMBean(getManagementContext(), log4jConfigView, objectName);
        }
	//开启所有连接
        startAllConnectors();
        getBroker().brokerServiceStarted();
        checkSystemUsageLimits();
	//启动信号
        startedLatch.countDown();
        getBroker().nowMasterBroker();
    }


开启所有连接
startAllConnectors();



public void startAllConnectors()
        throws Exception
    {
        Set durableDestinations = getBroker().getDurableDestinations();
        List al = new ArrayList();
        TransportConnector connector;
	//启动连接监听startTransportConnector(connector)
        for(Iterator iter = getTransportConnectors().iterator(); iter.hasNext(); al.add(startTransportConnector(connector)))
            connector = (TransportConnector)iter.next();

        if(al.size() > 0)
        {
            transportConnectors.clear();
            setTransportConnectors(al);
        }
        slave = false;
        URI uri = getVmConnectorURI();
        Map map = new HashMap(URISupport.parseParameters(uri));
        map.put("async", "false");
        uri = URISupport.createURIWithQuery(uri, URISupport.createQueryString(map));
        if(!stopped.get())
        {
	    //初始化线程执行器
            ThreadPoolExecutor networkConnectorStartExecutor = null;
            if(isNetworkConnectorStartAsync())
                networkConnectorStartExecutor = new ThreadPoolExecutor(0, 2147483647, 10L, TimeUnit.SECONDS, new SynchronousQueue(), new ThreadFactory() {

                    public Thread newThread(Runnable runnable)
                    {
                        Thread thread = new Thread(runnable, (new StringBuilder()).append("NetworkConnector Start Thread-").append(count++).toString());
                        thread.setDaemon(true);
                        return thread;
                    }

                    int count;
                    final BrokerService this$0;

            
            {
                this$0 = BrokerService.this;
                super();
                count = 0;
            }
                });
	    //启动NetworkConnector 
            for(Iterator iter = getNetworkConnectors().iterator(); iter.hasNext();)
            {
                final NetworkConnector connector = (NetworkConnector)iter.next();
                connector.setLocalUri(uri);
                connector.setBrokerName(getBrokerName());
                connector.setDurableDestinations(durableDestinations);
                if(getDefaultSocketURIString() != null)
                    connector.setBrokerURL(getDefaultSocketURIString());
                if(networkConnectorStartExecutor != null)
                    networkConnectorStartExecutor.execute(new Runnable() {

                        public void run()
                        {
                            try
                            {
                                BrokerService.LOG.info("Async start of {}", connector);
                                connector.start();
                            }
                            catch(Exception e)
                            {
                                BrokerService.LOG.error("Async start of network connector: {} failed", connector, e);
                            }
                        }

                        final NetworkConnector val$connector;
                        final BrokerService this$0;

            
            {
                this$0 = BrokerService.this;
                connector = networkconnector;
                super();
            }
                    });
                else
                    connector.start();
            }

            if(networkConnectorStartExecutor != null)
                ThreadPoolUtils.shutdown(networkConnectorStartExecutor);
            ProxyConnector connector;
            for(Iterator iter = getProxyConnectors().iterator(); iter.hasNext(); connector.start())
                connector = (ProxyConnector)iter.next();

            JmsConnector connector;
            for(Iterator iter = jmsConnectors.iterator(); iter.hasNext(); connector.start())
                connector = (JmsConnector)iter.next();

            Service service;
            for(Iterator i$ = services.iterator(); i$.hasNext(); service.start())
            {
                service = (Service)i$.next();
                configureService(service);
            }

        }
    }

来看启动连接监听
启动连接监听
startTransportConnector(connector)

public TransportConnector startTransportConnector(TransportConnector connector)
        throws Exception
    {
        //设置连接broker
        connector.setBrokerService(this);
	//设置任务工厂
        connector.setTaskRunnerFactory(getTaskRunnerFactory());
        MessageAuthorizationPolicy policy = getMessageAuthorizationPolicy();
        if(policy != null)
            connector.setMessageAuthorizationPolicy(policy);
        if(isUseJmx())
            connector = registerConnectorMBean(connector);
        connector.getStatistics().setEnabled(enableStatistics);
	//启动连接
        connector.start();
        return connector;
    }


public class TransportConnector
    implements Connector, BrokerServiceAware
{
   protected final CopyOnWriteArrayList connections;//连接信息
    protected TransportStatusDetector statusDector;
    private BrokerService brokerService;//broker服务
    private TransportServer server;//监听Server
    private URI uri;
    private BrokerInfo brokerInfo;
    private TaskRunnerFactory taskRunnerFactory;//任务工厂
    private MessageAuthorizationPolicy messageAuthorizationPolicy;
    private DiscoveryAgent discoveryAgent;
    private final ConnectorStatistics statistics;
    private URI discoveryUri;
    private String name;
    private boolean disableAsyncDispatch;
    private boolean enableStatusMonitor;
    private Broker broker;
    private boolean updateClusterClients;
    private boolean rebalanceClusterClients;
    private boolean updateClusterClientsOnRemove;
    private String updateClusterFilter;
    private boolean auditNetworkProducers;
    //允许连接的最大消费者与生产者
    private int maximumProducersAllowedPerConnection;
    private int maximumConsumersAllowedPerConnection;
    private PublishedAddressPolicy publishedAddressPolicy;
    private boolean allowLinkStealing;
    LinkedList peerBrokers;//peer
    public TransportConnector()
    {
        LOG = LoggerFactory.getLogger(org/apache/activemq/broker/TransportConnector);
        connections = new CopyOnWriteArrayList();
        brokerInfo = new BrokerInfo();
        statistics = new ConnectorStatistics();
        enableStatusMonitor = false;
        updateClusterClients = false;
        updateClusterClientsOnRemove = false;
        auditNetworkProducers = false;
        maximumProducersAllowedPerConnection = 2147483647;
        maximumConsumersAllowedPerConnection = 2147483647;
        publishedAddressPolicy = new PublishedAddressPolicy();
        peerBrokers = new LinkedList();
    }
}

从上面看初始化TransportConnector,就是初始化broker服务,允许连接的最大消费者与生产者等信息。

//启动连接
connector.start();


public void start()
        throws Exception
    {
        broker = brokerService.getBroker();
        brokerInfo.setBrokerName(broker.getBrokerName());
        brokerInfo.setBrokerId(broker.getBrokerId());
        brokerInfo.setPeerBrokerInfos(broker.getPeerBrokerInfos());
        brokerInfo.setFaultTolerantConfiguration(broker.isFaultTolerantConfiguration());
        brokerInfo.setBrokerURL(broker.getBrokerService().getDefaultSocketURIString());
	//设置Server接受连接监听器
        getServer().setAcceptListener(new TransportAcceptListener() {

            public void onAccept(final Transport transport)
            {
                try
                {
                    brokerService.getTaskRunnerFactory().execute(new Runnable() {

                        public void run()
                        {
                            try
                            {
                                if(!brokerService.isStopping())
                                {
				    //接受连接后,创建连接,启动连接,这个时候是不是
				    //与前面联系上了,当启动连接时,启动会话,启动
				    //会话执行器,通知消费者消费消息
                                    Connection connection = createConnection(transport);
                                    connection.start();
                                } else
                                {
                                    throw new BrokerStoppedException((new StringBuilder()).append("Broker ").append(brokerService).append(" is being stopped").toString());
                                }
                            }
                        }

                        final Transport val$transport;
                        final _cls1 this$1;

                    
                    {
                        this$1 = _cls1.this;
                        transport = transport1;
                        super();
                    }
                    });
                }
            }
            final TransportConnector this$0;


            
            {
                this$0 = TransportConnector.this;
                super();
            }
        });
        getServer().setBrokerInfo(brokerInfo);
	//启动server
        getServer().start();
	//slave发现代理
        DiscoveryAgent da = getDiscoveryAgent();
        if(da != null)
        {
            da.registerService(getPublishableConnectString());
            da.start();
        }
        if(enableStatusMonitor)
        {
            statusDector = new TransportStatusDetector(this);
            statusDector.start();
        }
    }

 public TransportServer getServer()
        throws IOException, URISyntaxException
    {
        if(server == null)
	    //设置Server
            setServer(createTransportServer());
        return server;
    }
    创建TransportServer
  protected TransportServer createTransportServer()
        throws IOException, URISyntaxException
    {
        if(brokerService == null)
            throw new IllegalArgumentException("You must specify the brokerService property. Maybe this connector should be added to a broker?");
        else
            return TransportFactorySupport.bind(brokerService, uri);
    }
    //TransportFactorySupport
    //绑定broker服务于URI
  public static TransportServer bind(BrokerService brokerService, URI location)
        throws IOException
    {
        TransportFactory tf;
	//根据以前的文章这个应该很熟悉,TransportFactory获取工厂,实际为TcpTransportFactory
        tf = TransportFactory.findTransportFactory(location);
        if(brokerService != null && (tf instanceof BrokerServiceAware))
            ((BrokerServiceAware)tf).setBrokerService(brokerService);
        TransportServer transportserver;
        if(brokerService != null)
            SslContext.setCurrentSslContext(brokerService.getSslContext());
	//绑定地址
        transportserver = tf.doBind(location);
        SslContext.setCurrentSslContext(null);
        return transportserver;
        Exception exception;
        exception;
        SslContext.setCurrentSslContext(null);
        throw exception;
    }

//TcpTransportFactory
   public class TcpTransportFactory extends TransportFactory
{
ublic TransportServer doBind(URI location)
        throws IOException
    {
        TcpTransportServer server;
        Map options = new HashMap(URISupport.parseParameters(location));
	//创建SOCKET工厂
        ServerSocketFactory serverSocketFactory = createServerSocketFactory();
        server = createTcpTransportServer(location, serverSocketFactory);
	//设置Server协议
        server.setWireFormatFactory(createWireFormatFactory(options));
        IntrospectionSupport.setProperties(server, options);
        Map transportOptions = IntrospectionSupport.extractProperties(options, "transport.");
        server.setTransportOption(transportOptions);
	//绑定Server
        server.bind();
        return server;
        URISyntaxException e;
        e;
        throw IOExceptionSupport.create(e);
    }

再看TcpTransportServer
public class TcpTransportServer extends TransportServerThreadSupport
    implements ServiceListener
{   
   protected ServerSocket serverSocket;//ServerSocket
    protected SelectorSelection selector;
    protected int backlog;
    protected WireFormatFactory wireFormatFactory;
    protected final TcpTransportFactory transportFactory;//transportFactory
    protected long maxInactivityDuration;
    protected long maxInactivityDurationInitalDelay;
    protected int minmumWireFormatVersion;
    protected boolean useQueueForAccept;
    protected boolean allowLinkStealing;
    protected boolean trace;
    protected int soTimeout;
    protected int socketBufferSize;//缓存大小
    protected int connectionTimeout;//连接超时时间
    protected String logWriterName;
    protected boolean dynamicManagement;
    protected boolean startLogging;
    protected final ServerSocketFactory serverSocketFactory;
    protected BlockingQueue socketQueue;//socket的队列
    protected Thread socketHandlerThread;
    protected int maximumConnections;
    protected AtomicInteger currentTransportCount;//连接数
    public TcpTransportServer(TcpTransportFactory transportFactory, URI location, ServerSocketFactory serverSocketFactory)
        throws IOException, URISyntaxException
    {
        super(location);
        backlog = 5000;
        wireFormatFactory = new OpenWireFormatFactory();
        maxInactivityDuration = 30000L;
        maxInactivityDurationInitalDelay = 10000L;
        useQueueForAccept = true;
        trace = false;
        soTimeout = 0;
        socketBufferSize = 65536;
        connectionTimeout = 30000;
        logWriterName = TransportLoggerSupport.defaultLogWriterName;
        dynamicManagement = false;
        startLogging = true;
        socketQueue = new LinkedBlockingQueue();
        maximumConnections = 2147483647;
        currentTransportCount = new AtomicInteger();
        this.transportFactory = transportFactory;
        this.serverSocketFactory = serverSocketFactory;
    }
}

初始化TcpTransportServer就是,连接缓存大小,连接延时,协议格式化工厂,socketServer工厂等;


先看TcpTransportServer绑定
 public void bind()
        throws IOException
    {
        URI bind = getBindLocation();
        String host = bind.getHost();
        host = host != null && host.length() != 0 ? host : "localhost";
        InetAddress addr = InetAddress.getByName(host);
        try
        {
	   //根据ip和port创建serverSocket
            serverSocket = serverSocketFactory.createServerSocket(bind.getPort(), backlog, addr);
            configureServerSocket(serverSocket);
        }
  }


再看启动server
getServer().start();



public class TcpTransportServer extends TransportServerThreadSupport
    implements ServiceListener

public abstract class TransportServerThreadSupport extends TransportServerSupport
    implements Runnable


public abstract class TransportServerSupport extends ServiceSupport
    implements TransportServer

看到ServiceSupport,实际调用的为doStart
//TransportServerThreadSupport
protected void doStart()
        throws Exception
    {
        LOG.info((new StringBuilder()).append("Listening for connections at: ").append(getConnectURI()).toString());
        runner = new Thread(null, this, (new StringBuilder()).append("ActiveMQ Transport Server: ").append(toString()).toString(), stackSize);
        runner.setDaemon(daemon);
        runner.setPriority(9);
        runner.start();
    }

同时启动TcpTransportServer线程
//TcpTransportServer
 public void run()
    {
       //从serverSocket获取通道,java nio
        final ServerSocketChannel chan = serverSocket.getChannel();
        if(chan != null)
            try
            {
                chan.configureBlocking(false);
                selector = SelectorManager.getInstance().register(chan, new org.apache.activemq.transport.nio.SelectorManager.Listener() {
                    //通道选择器
                    public void onSelect(SelectorSelection sel)
                    {
                        try
                        {
                            SocketChannel sc = chan.accept();
                            if(sc != null)
                                if(isStopped() || getAcceptListener() == null)
                                    sc.close();
                                else
                                if(useQueueForAccept)
                                    socketQueue.put(sc.socket());
                                else
                                    handleSocket(sc.socket());
                        }
                        catch(Exception e)
                        {
                            onError(sel, e);
                        }
                    }

                    public void onError(SelectorSelection sel, Throwable error)
                    {
                        Exception e = null;
                        if(error instanceof Exception)
                            e = (Exception)error;
                        else
                            e = new Exception(error);
                        if(!isStopping())
                            onAcceptError(e);
                        else
                        if(!isStopped())
                        {
                            TcpTransportServer.LOG.warn("run()", e);
                            onAcceptError(e);
                        }
                    }

                    final ServerSocketChannel val$chan;
                    final TcpTransportServer this$0;

            
            {
                this$0 = TcpTransportServer.this;
                chan = serversocketchannel;
                super();
            }
                });
                selector.setInterestOps(16);
                selector.enable();
            }
            catch(IOException ex)
            {
                selector = null;
            }
        else
            do
            {
                if(isStopped())
                    break;
                Socket socket = null;
                try
                {
		    //第一次,没有socket,则创建serverSocket
                    socket = serverSocket.accept();
                    if(socket != null)
                        if(isStopped() || getAcceptListener() == null)
                            socket.close();
                        else
                        if(useQueueForAccept)
			    //将serverSocket添加socketQueue
                            socketQueue.put(socket);
                        else
                            handleSocket(socket);
                }
            } while(true);
    }



 protected final void handleSocket(Socket socket)
    {
        boolean closeSocket = true;
        try
        {
            if(currentTransportCount.get() >= maximumConnections)
                throw new ExceededMaximumConnectionsException("Exceeded the maximum number of allowed client connections. See the 'maximumConnections' property on the TCP transport configuration URI in the ActiveMQ configuration file (e.g., activemq.xml)");
            HashMap options = new HashMap();
            options.put("maxInactivityDuration", Long.valueOf(maxInactivityDuration));
            options.put("maxInactivityDurationInitalDelay", Long.valueOf(maxInactivityDurationInitalDelay));
            options.put("minmumWireFormatVersion", Integer.valueOf(minmumWireFormatVersion));
            options.put("trace", Boolean.valueOf(trace));
            options.put("soTimeout", Integer.valueOf(soTimeout));
            options.put("socketBufferSize", Integer.valueOf(socketBufferSize));
            options.put("connectionTimeout", Integer.valueOf(connectionTimeout));
            options.put("logWriterName", logWriterName);
            options.put("dynamicManagement", Boolean.valueOf(dynamicManagement));
            options.put("startLogging", Boolean.valueOf(startLogging));
            options.putAll(transportOptions);
            WireFormat format = wireFormatFactory.createWireFormat();
            Transport transport = createTransport(socket, format);
            closeSocket = false;
            if(transport instanceof ServiceSupport)
                ((ServiceSupport)transport).addServiceListener(this);
            Transport configuredTransport = transportFactory.serverConfigure(transport, format, options);
	    //连接监听器接受连接,创建连接,开启连接
            getAcceptListener().onAccept(configuredTransport);
            currentTransportCount.incrementAndGet();
        }
       
    }

在brokerService启动过程中有设置了连接监听器
public void start()
        throws Exception
    {
        broker = brokerService.getBroker();
        brokerInfo.setBrokerName(broker.getBrokerName());
        brokerInfo.setBrokerId(broker.getBrokerId());
        brokerInfo.setPeerBrokerInfos(broker.getPeerBrokerInfos());
        brokerInfo.setFaultTolerantConfiguration(broker.isFaultTolerantConfiguration());
        brokerInfo.setBrokerURL(broker.getBrokerService().getDefaultSocketURIString());
	//设置Server接受连接监听器
        getServer().setAcceptListener(new TransportAcceptListener() {

            public void onAccept(final Transport transport)
            {
                try
                {
                    brokerService.getTaskRunnerFactory().execute(new Runnable() {

                        public void run()
                        {
                            try
                            {
                                if(!brokerService.isStopping())
                                {
				    //接受连接后,创建连接,启动连接,这个时候是不是
				    //与前面联系上了,当启动连接时,启动会话,启动
				    //会话执行器,通知消费者消费消息
                                    Connection connection = createConnection(transport);
                                    connection.start();
                                } 
                            }
                        }
}

//TransportConnector
 protected Connection createConnection(Transport transport)
        throws IOException
    {
        TransportConnection answer = new TransportConnection(this, transport, broker, disableAsyncDispatch ? null : taskRunnerFactory, brokerService.getTaskRunnerFactory());
        boolean statEnabled = getStatistics().isEnabled();
        answer.getStatistics().setEnabled(statEnabled);
        answer.setMessageAuthorizationPolicy(messageAuthorizationPolicy);
        return answer;
    }


总结:
从activemq脚本,可以看出启动ActiveMQ实际是启动,bin文件夹下的其实activemq.jar包中有一个类为Main,这就是active的启动入口,Main主要是加载lib目录和ClassPath,初始化类加载器,委托给ShellCommand,由ShellCommand根据命令描述去执行,如果是Version和HELP,则打印信息,若是启动命令,则通过XBeanBrokerFactory创建BrokerService,这个过程主要利用的Spring的bean容器机制,然后启动BrokerService,主要启动持久化适配器,JMX连接,上下文关系器,最后启动所有网络连接,及TcpTransport连接,默认使用的是openwire:tcp,所以我们就看一下
TcpTransportServer,TcpTransportServer有TcpTransportFactory创建并配置OpenWire协议转换器,启动TcpTransportServer,就是从ServerSocketFactory获取ServerSocket,并绑定ip和port,监听连接,并设置ServerSocket的监听器org.apache.activemq.transport.nio.SelectorManager.Listener,这个用的
是java nio。





public final class CommandContext
{
 //activemq 命令输出格式工具
 private OutputFormatter formatter;
 }

public interface OutputFormatter
{
    public abstract OutputStream getOutputStream();
    public abstract void printMBean(ObjectInstance objectinstance);
    public abstract void printMBean(ObjectName objectname);
    public abstract void printMBean(AttributeList attributelist);
    public abstract void printMBean(Map map);
    public abstract void printMBean(Collection collection);
    public abstract void printMessage(Map map);
    //打印消息
    public abstract void printMessage(Message message);
    public abstract void printMessage(Collection collection);
    //打印帮助信息
    public abstract void printHelp(String as[]);
    public abstract void printInfo(String s);
    public abstract void printException(Exception exception);
    public abstract void printVersion(String s);
    public abstract void print(Map map);
    public abstract void print(String as[]);
    public abstract void print(Collection collection);
    public abstract void print(String s);
}


//SelectorManager
public final class SelectorManager
{
    public static final SelectorManager SINGLETON = new SelectorManager();
    private Executor selectorExecutor;
    private Executor channelExecutor;
    private final LinkedList freeWorkers = new LinkedList();
    private int maxChannelsPerWorker;
    public static interface Listener
    {

        public abstract void onSelect(SelectorSelection selectorselection);

        public abstract void onError(SelectorSelection selectorselection, Throwable throwable);
    }


    public SelectorManager()
    {
        selectorExecutor = createDefaultExecutor();
        channelExecutor = selectorExecutor;
        maxChannelsPerWorker = 1024;
    }

    protected ExecutorService createDefaultExecutor()
    {
        ThreadPoolExecutor rc = new ThreadPoolExecutor(getDefaultCorePoolSize(), getDefaultMaximumPoolSize(), getDefaultKeepAliveTime(), TimeUnit.SECONDS, new SynchronousQueue(), new ThreadFactory() {

            public Thread newThread(Runnable runnable)
            {
                i++;
                Thread t = new Thread(runnable, (new StringBuilder()).append("ActiveMQ NIO Worker ").append(i).toString());
                return t;
            }

            private long i;
            final SelectorManager this$0;

            
            {
                this$0 = SelectorManager.this;
                super();
                i = 0L;
            }
        });
        return rc;
    }

    private static int getDefaultCorePoolSize()
    {
        return Integer.getInteger("org.apache.activemq.transport.nio.SelectorManager.corePoolSize", 0).intValue();
    }

    private static int getDefaultMaximumPoolSize()
    {
        return Integer.getInteger("org.apache.activemq.transport.nio.SelectorManager.maximumPoolSize", 2147483647).intValue();
    }

    private static int getDefaultKeepAliveTime()
    {
        return Integer.getInteger("org.apache.activemq.transport.nio.SelectorManager.keepAliveTime", 30).intValue();
    }

    public static SelectorManager getInstance()
    {
        return SINGLETON;
    }

    public synchronized SelectorSelection register(AbstractSelectableChannel selectableChannel, Listener listener)
        throws IOException
    {
        SelectorSelection selection;
        for(selection = null; selection == null;)
            if(freeWorkers.size() > 0)
            {
                SelectorWorker worker = (SelectorWorker)freeWorkers.getFirst();
                if(worker.isReleased())
                {
                    freeWorkers.remove(worker);
                } else
                {
                    worker.retain();
                    selection = new SelectorSelection(worker, selectableChannel, listener);
                }
            } else
            {
                SelectorWorker worker = new SelectorWorker(this);
                freeWorkers.addFirst(worker);
                selection = new SelectorSelection(worker, selectableChannel, listener);
            }

        return selection;
    }

    synchronized void onWorkerFullEvent(SelectorWorker worker)
    {
        freeWorkers.remove(worker);
    }

    public synchronized void onWorkerEmptyEvent(SelectorWorker worker)
    {
        freeWorkers.remove(worker);
    }

    public synchronized void onWorkerNotFullEvent(SelectorWorker worker)
    {
        freeWorkers.addFirst(worker);
    }

    public Executor getChannelExecutor()
    {
        return channelExecutor;
    }

    public void setChannelExecutor(Executor channelExecutor)
    {
        this.channelExecutor = channelExecutor;
    }

    public int getMaxChannelsPerWorker()
    {
        return maxChannelsPerWorker;
    }

    public void setMaxChannelsPerWorker(int maxChannelsPerWorker)
    {
        this.maxChannelsPerWorker = maxChannelsPerWorker;
    }

    public Executor getSelectorExecutor()
    {
        return selectorExecutor;
    }

    public void setSelectorExecutor(Executor selectorExecutor)
    {
        this.selectorExecutor = selectorExecutor;
    }

   

}
ActiveMQ
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