Zookeeper实战（开发重点）Java API-CFANZ编程社区

API应用

IDEA环境搭建

1．创建一个Maven工程
2．添加pom文件

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.8.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper -->
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.10</version>
        </dependency>
</dependencies>

3．拷贝log4j.properties文件到项目根目录
需要在项目的resources目录下，新建一个文件，命名为"log4j.properties"，
在文件中填入。

log4j.rootLogger=INFO, stdout  
log4j.appender.stdout=org.apache.log4j.ConsoleAppender  
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout  
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n  
log4j.appender.logfile=org.apache.log4j.FileAppender  
log4j.appender.logfile.File=target/spring.log  
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout  
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

编写Java代码操作ZK

1 创建ZooKeeper客户端

private static String connectString =
 "hadoop102:2181,hadoop103:2181,hadoop104:2181";
    private static int sessionTimeout = 2000;
    private ZooKeeper zkClient = null;

    @Before
    public void init() throws Exception {

    zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {

            @Override
            public void process(WatchedEvent event) {

                // 收到事件通知后的回调函数（用户的业务逻辑）
                System.out.println(event.getType() + "--" + event.getPath());

                // 再次启动监听
                try {
                    zkClient.getChildren("/", true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

创建子节点

// 创建子节点
@Test
public void create() throws Exception {

        // 参数1：要创建的节点的路径； 参数2：节点数据 ； 参数3：节点权限 ；参数4：节点的类型
        String nodeCreated = zkClient.create("/dev1", "caocao".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}

获取子节点并监听节点变化

// 获取子节点
@Test
public void getChildren() throws Exception {

        List<String> children = zkClient.getChildren("/", true);

        for (String child : children) {
            System.out.println(child);
        }

        // 延时阻塞
        Thread.sleep(Long.MAX_VALUE);
}

判断Znode是否存在

// 判断znode是否存在
@Test
public void exist() throws Exception {

    Stat stat = zkClient.exists("/eclipse", false);

    System.out.println(stat == null ? "not exist" : "exist");
}