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多线程java.Thread

路西法阁下 2022-04-13 阅读 163
java

线程实现
线程同步

  • 进程(Process)与线程(Thread)
    进程就是一个程序(方法执行的过程)它是一个动态的概念,是系统分配的
    通常在一个进程中包含多个线程(至少有一个),线程是cpu调度和执行的单位
    线程先后顺序不能人为干预
    main线程 gc(垃圾回收)线程

1.线程的创建

  • Thread class------继承Thread类(重点)
    1.继承Thread类
    2.重写run();方法 编写线程执行体
    3.创建线程对象，调用start();方法启动线程
    测试
package com.Threadtest.demo01;

//创建线程方式一：继承Thread类；重写run（）方法；调用start开启线程
//注意 线程开启不一定立即执行，由cpu调度执行
public class TestThread01 extends Thread{
    @Override
    public void run() {
        //run方法线程体
        for(int i =0;i<20;i++){
            System.out.println("我在看代码=========="+i);
        }
    }
    public static void main(String[] args) {
        //main线程，主线程

        //创建一个线程对象
        TestThread01 testThread01 = new TestThread01();
        //调用start方法，开启线程    交替执行  如果调用run方法就会先执行run方法的
        testThread01.start();


        for(int i =0;i<2000;i++){
            System.out.println("我在学习多线程----"+i);
        }
    }
}

下载图片

package com.Threadtest.demo01;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;

//练习Thread，实现多线程同步下载图片
public class TestThread02 extends Thread{
    private String url;     //网路图片地址
    private String name;    //保存的文件名

    public TestThread02(String url,String name){
        this.url=url;
        this.name=name;
    }

    //下载图片线程的执行体
    @Override
    public void run() {
        WebDownloader webDownloader = new WebDownloader();
        webDownloader.downloader(url,name);
        System.out.println("下载了文件名为："+name);
    }

    public static void main(String[] args) {
        TestThread02 t1 = new TestThread02("https://www.kuangstudy.com/assert/img/weixin.jpg","1.jpg");
        TestThread02 t2 = new TestThread02("https://www.kuangstudy.com/assert/img/weixin.jpg","2.jpg");
        TestThread02 t3 = new TestThread02("https://www.kuangstudy.com/assert/img/weixin.jpg","3.jpg");

        //这三个同时执行
        t1.start();
        t2.start();
        t3.start();

    }

}

//下载器
class WebDownloader{
    //下载方法
    public void downloader(String url,String name){
        try {
            FileUtils.copyURLToFile(new URL(url),new File(name));
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("io异常，downloader出现异常");
        }
    }
}
  • Runnable接口-----实现Runnable接口(重点)
    1.定义MyRunnable类实现Runnable接口
    2.实现run()方法，编写线程执行体
    3.创建线程对象，调用start()方法启动线程
package com.Threadtest.demo01;

//创建线程方式2：实现runnabnle接口，重写run方法，执行线程需要丢入runnable接口实现类，调用start方法
public class TestThread03 implements Runnable{
   @Override
   public void run() {
       //run方法线程体
       for(int i =0;i<20;i++){
           System.out.println("我在看代码=========="+i);
       }
   }
   public static void main(String[] args) {
       //创建 runnable接口的实现类对象
       TestThread03 testThread03 = new TestThread03();

       //创建线程对象，通过线程对象来开启我们的线程 代理
//        Thread thread = new Thread(testThread03);
//        thread.start();
       new Thread(testThread03).start();

       for(int i =0;i<2000;i++){
           System.out.println("我在学习多线程----"+i);
       }
   }
}

  • Callable接口--------实现Callable接口(工作三到五后是重点)

  • 小结
    –继承Thread类
    1.子类继承Thread类具备多线程能力
    2.启动线程：子类对象.start()
    3.不建议使用：避免OOP单继承局限性
    –实现Runnable接口
    1.实现接口Runnabnle具有多线程能力
    2.启动线程：传入目标对象+Thread对象.start()
    3.推荐使用：避免单继承局限性，灵活方便，方便同一个对象被多个线程使用

买票发现问题 多个线程操作同一个资源的情况下，线程不安全，数据紊乱

package com.Threadtest.demo01;

//多个线程同时操作同一个对象
//买火车票的例子
//发现问题：多个线程操作同一个资源的情况下，线程不安全，数据紊乱
public class TestThread04 implements Runnable{

    //票数
    private int ticketNums = 10;

    @Override
    public void run() {
        while(true){                            //获取线程名字
            if(ticketNums<=1){
                break;
            }
            //模拟延时
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"---》拿到了第"+ticketNums--+"票");
        }
    }

    public static void main(String[] args) {
        TestThread04 t1 = new TestThread04();
        new Thread(t1,"小明").start();
        new Thread(t1,"老师").start();
        new Thread(t1,"黄牛").start();

    }
}

龟兔赛跑

package com.Threadtest.demo02;

//模拟龟兔赛跑
public class Race implements Runnable{

    //胜利者
    private static String winner;

    @Override
    public void run() {
        for (int i = 0; i <= 100; i++) {

            if(Thread.currentThread().getName().equals("兔子")&&i%10==0){
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            //判断比赛是否结束
            boolean flag=gameOver(i);
            //如果比赛结束了 就停止程序
            if (flag){
                break;
            }

            System.out.println(Thread.currentThread().getName()+"-->跑了"+i+"步");
        }
    }

    //判断是否完成比赛
    private boolean gameOver(int steps){
        //判断是否有胜利者
        if(winner!=null){//已经存在胜利者了
            return true;
        }{
            if(steps>=100){
                winner=Thread.currentThread().getName();
                System.out.println("winner is"+winner);
                return true;
            }
        }
        return false;
    }

    public static void main(String[] args) {
        Race race = new Race();
        new Thread(race,"兔子").start();
        new Thread(race,"乌龟").start();
    }

}
  • Callable接口--------实现Callable接口(工作三到五后是重点)
package com.Threadtest.demo02;
import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;

//线程创建三：实现callable接口
/*
callable好处
1.可以定义返回值
2.可以抛出异常
 */
public class TestCallable implements Callable {
        private String url;     //网路图片地址
        private String name;    //保存的文件名

        public TestCallable(String url,String name){
            this.url=url;
            this.name=name;
        }

        //下载图片线程的执行体
        @Override
        public Boolean call() {
            WebDownloader webDownloader = new WebDownloader();
            webDownloader.downloader(url,name);
            System.out.println("下载了文件名为："+name);
            return true;
        }

        public static void main(String[] args) throws ExecutionException, InterruptedException {
            TestCallable t1 = new TestCallable("https://www.kuangstudy.com/assert/img/weixin.jpg","1.jpg");
            TestCallable t2 = new TestCallable("https://www.kuangstudy.com/assert/img/weixin.jpg","2.jpg");
            TestCallable t3 = new TestCallable("https://www.kuangstudy.com/assert/img/weixin.jpg","3.jpg");

            //创建执行服务
            ExecutorService ser = Executors.newFixedThreadPool(3);
            //提交执行
            Future<Boolean> r1 = ser.submit(t1);
            Future<Boolean> r2 = ser.submit(t2);
            Future<Boolean> r3 = ser.submit(t3);
            //获取结果
            boolean rs1 = r1.get();
            boolean rs2 = r2.get();
            boolean rs3 = r3.get();

            System.out.println(rs1);
            System.out.println(rs1);
            System.out.println(rs1);
            //关闭服务
            ser.shutdown();
        }



    //下载器
    class WebDownloader{
        //下载方法
        public void downloader(String url,String name){
            try {
                FileUtils.copyURLToFile(new URL(url),new File(name));
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("io异常，downloader出现异常");
            }
        }
    }

}
  • 静态代理模式+
package com.Proxy.demo01;

//代理模式总结
//真实对象和代理对象都要实现同一个接口
//代理对象，代理真实角色
//好处
    //代理对象可以做很多真实对象做不了的事情
    //真实对象专注做自己的事情
public class StaticProxy {

    public static void main(String[] args) {
        
        new Thread(()-> System.out.println("我爱你")).start();
        new WeddingCompany(new You()).HappyMarry();
    }

}
interface Marry{
    //人间四大喜事
        //久旱逢甘露
        //他乡遇故知
        //洞房花烛夜
        //金榜题名时
    void HappyMarry();
}
//真是角色
class You implements Marry{

    @Override
    public void HappyMarry() {
        System.out.println("结婚了结婚了");
    }
}
//代理角色
class WeddingCompany implements Marry{

    private Marry targer;

    public WeddingCompany(Marry targer) {
        this.targer = targer;
    }

    @Override
    public void HappyMarry() {
        before();
        this.targer.HappyMarry();//真实角色
        after();
    }

    private void after() {
        System.out.println("结婚之后，收尾款");
    }

    private void before() {
        System.out.println("结婚之前， 布置现场");
    }
}
  • Lamba表达式
    任何接口，如果只包含唯一一个抽象方法，那么他就是一个函数式接口
public interface Runnable{
	public abstract void run();
}

转化（简化）

package com.lambda;

/*
推导lambda表达式
*/

public class TestLambda1 {

   //3.静态内部类
   static class Like2 implements ILike{
       @Override
       public void lambda() {
           System.out.println("i like lamdba2");
       }
   }

   public static void main(String[] args) {
       ILike like = new Like();
       like.lambda();
       like = new Like2();
       like.lambda();

       //4,局部内部类
       class Like3 implements ILike{
           @Override
           public void lambda() {
               System.out.println("i like lamdba3");
           }
       }
       like = new Like3();
       like.lambda();

       //5.匿名内部类，没有类的名字，必须借助接口或者父类
       like = new ILike() {
           @Override
           public void lambda() {
               System.out.println("i like lamdba4");
           }
       };
       like.lambda();

       //6.用lamdba简化
       like = ()->{
           System.out.println("i like lamdba5");
       };
       like.lambda();
   }
}

//1.定义一个函数式接口
interface ILike{
   void lambda();
}
//2.实现类
class Like implements ILike{
   @Override
   public void lambda() {
       System.out.println("i like lamdba");
   }
}

再次简化

package com.lambda;

public class TestLamdba {

    public static void main(String[] args) {
        ILove love = null;

/*        ILove iLove = (int a)->{
            System.out.println("我爱你"+a);
        };
        //简化1.去掉参数类型
        love = (a)->{
            System.out.println("i love you "+a);
        };
        //简化2，简化括号
        love = a->{
            System.out.println("i love you "+a);
        };*/
        //简化3.去掉花括号
        love = a-> System.out.println("i love you "+a);
        //总结：
        //lamdba表达式只能有一行代码的情况下才能简化成一行，如果有多行，那么就用代码块包裹。
        //前提是接口为函数式接口
        //多个参数也可以，但需要在参数的位置加上括号
        love.love(521);
    }
}
interface ILove{

    void love(int a);
}

线程状态

在这里插入图片描述

  • 停止线程
package com.Threadtest.demo02;

//测试stop
//1.建议线程正常停止---》利用次数，不建议死循环
//2.建议使用标志位----》设置一个标志位
//3.不用使用stop或者destory等过时或者JDK不建议使用的方法
//
public class TestStop implements Runnable{

   //1.设置一个标志位
   private boolean flag=true;

   @Override
   public void run() {
       int i=0;
       while(flag){
           System.out.println("run.....Thread"+i++);
       }
   }
   //2.设置一个公开的方法 用来转换标志位
   public void stop(){
       this.flag=false;
   }

   public static void main(String[] args) {
       TestStop testStop = new TestStop();
       for (int i = 0; i < 1000; i++) {
           if(i==900){
               //调用stop方法切换标识位，让线程停止
               testStop.stop();
               System.out.println("线程停止了");
           }
       }


   }
}
  • 线程休眠
    sleep(时间)指定当前线程阻塞的毫秒数
    sleep存在异常InterruptedException
    sleep时间达到后线程进入就绪状态
    sleep可以模拟网络延时，倒计时等
    每一个对象都有一个锁，sleep不会释放锁
  • 模拟网络延迟的作用：放大问题的发生性
package com.Threadtest.demo02;

import com.Threadtest.demo01.TestThread04;
//模拟网络延迟的作用：放大问题的发生性
public class TestSleep implements Runnable{
    //票数
    private int ticketNums = 10;

    @Override
    public void run() {
        while(true){                            //获取线程名字
            if(ticketNums<=1){
                break;
            }
            //模拟延时
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"---》拿到了第"+ticketNums--+"票");
        }
    }

    public static void main(String[] args) {
        TestSleep t1 = new TestSleep();
        new Thread(t1,"小明").start();
        new Thread(t1,"老师").start();
        new Thread(t1,"黄牛").start();

    }
}
  • //模拟倒计时
package com.Threadtest.demo02;

import java.text.SimpleDateFormat;
import java.util.Date;

//模拟倒计时
public class TestSleep2 {


    public static void main(String[] args) {
        //打印当前系统时间
        Date starttime = new Date(System.currentTimeMillis());//获取当前系统时间

        while(true){
            try {
                Thread.sleep(1000);
                System.out.println(new SimpleDateFormat("HH:mm:ss").format(starttime));
                starttime = new Date(System.currentTimeMillis());//更新当前时间
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }


    }
    //模拟倒计时
    public static void tenDown() throws InterruptedException {
        int num = 10;
        while(true){
            Thread.sleep(1000);
            System.out.println(num--);
            if(num<0){
                break;
            }
        }
    }
}
  • 线程礼让yield
    让当前执行的线程暂停，但不堵塞
    将线程从运行状态转为就绪状态
    让cpu重新调度，礼让不一定成功，看cpu心情
package com.Threadtest.demo02;

//测试礼让线程
//礼让不一定成功，看cpu心情
public class Testyield {

   public static void main(String[] args) {
   MyYield myYield = new MyYield();
   new Thread(myYield,"a").start();
   new Thread(myYield,"b").start();

   }
}

class MyYield implements Runnable{

   @Override
   public void run() {
       System.out.println(Thread.currentThread().getName()+"线程开始执行");
       //Thread.yield();
       System.out.println(Thread.currentThread().getName()+"线程停止执行");
   }
}
/*成功的
a线程开始执行
b线程开始执行
a线程停止执行
b线程停止执行
不成功的
a线程开始执行
a线程停止执行
b线程开始执行
b线程停止执行
*/
  • 线程强制执行Join
package com.Threadtest.demo02;

//想象为插队
//强制执行 特别霸道
//坏处：容易造成线程堵塞
public class TestJoin implements Runnable{

   @Override
   public void run() {
       for (int i = 0; i < 100; i++) {
           System.out.println("线程vip来了"+i);
       }
   }

   public static void main(String[] args) throws InterruptedException {
       //启动我们的线程
       TestJoin testJoin = new TestJoin();
       new Thread(testJoin).start();

       //主线程
       for (int i = 0; i <1000 ; i++) {
           if (i==200){
               new Thread(testJoin).join();//插队
           }
           System.out.println("main"+i);
       }
   }
}
  • 观察测试线程的状态
package com.Threadtest.demo02;

//观察测试线程的状态
public class TestState {
   public static void main(String[] args) throws InterruptedException {
       Thread thread = new Thread(()->{
       for (int i = 0; i <5 ; i++) {
           try {
               Thread.sleep(1000);
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
       }
           System.out.println("///");
       });

       //观察状态
       Thread.State state =thread.getState();
       System.out.println(state);//NEW

       //观察启动后
       thread.start();//启动线程
       state = thread.getState();
       System.out.println(state);//Run
       while (state !=Thread.State.TERMINATED){//只要线程不终止，就一直输出状态
           Thread.sleep(100);
           state = thread.getState();//更新线程状态
           System.out.println(state);//输出线程状态
       }
//        thread.start();线程死了之后就不能再次启动了 
   }
}
  • 线程优先级priority
    没有指定的setPriority 默认优先级为5
package com.Threadtest.demo02;

public class TestPriority {

    public static void main(String[] args) {
        //主线程默认优先级
        System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
        MyPriority myPriority = new MyPriority();

        Thread t1 = new Thread(myPriority);
        Thread t2 = new Thread(myPriority);
        Thread t3 = new Thread(myPriority);
        Thread t4 = new Thread(myPriority);
        Thread t5 = new Thread(myPriority);
        Thread t6 = new Thread(myPriority);

        //先设置优先级，再启动
        t1.start();
        t2.setPriority(1);
        t2.start();
        t3.setPriority(4);
        t3.start();

        t4.setPriority(Thread.MAX_PRIORITY); //MAX_PRIORITY==10
        t4.start();

        t5.setPriority(8);
        t5.start();

        t6.setPriority(7);
        t6.start();
    }
}
class MyPriority implements Runnable{

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
    }
}
  • 守护线程
package com.Threadtest.demo02;

//测试守护线程
//上帝守护你
public class TestDaemon {

   public static void main(String[] args) {
       God god = new God();
       You you = new You();

       Thread thread = new Thread(god);
       thread.setDaemon(true);//默认false是用户线程 ， 正常的线程都是用户线程

       thread.start();//上帝守护线程启动
                       //你没了，上帝就不守护你了   但是关闭虚拟机需要一段时间，所有会再运行一会儿
       new Thread(you).start();//你 用户线程启动

   }
}

//上帝
class God implements Runnable{

   @Override
   public void run() {
       while(true){
           System.out.println("++++++++++++上帝保佑着你");
       }
   }
}

//你
class You implements Runnable{

   @Override
   public void run() {
       for (int i = 0; i < 36500; i++) {
           System.out.println("一生要开心的或者");
       }
       System.out.println("=============goodbye word=========");
   }
}
  • 线程同步synchornized
    并发：多个线程访问同一个对象
    条件：队列加锁
    –1.不安全的买票
package com.Threadtest.syn;

//不安全的买票
//线程不安全 有负数
public class UnsafeBuyTicket {

    public static void main(String[] args) {
        BuyTicket station = new BuyTicket();

        new Thread(station,"苦逼的我").start();
        new Thread(station,"牛逼的你").start();
        new Thread(station,"傻逼的黄牛").start();

    }

}

class BuyTicket implements Runnable{

    //票
    private int ticketNums = 10;
    boolean flag = true;//外部停止方式
    @Override
    public void run() {
        //买票
        while(flag){
            buy();
        }
    }

    private void buy(){
        //判断是否有票
        if(ticketNums<=0){
            flag = false;
            return;
        }

        //模拟延时
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        //买票
        System.out.println(Thread.currentThread().getName()+"拿到"+ticketNums--);
    }

}

–2.不安全的银行

package com.Threadtest.syn;

//不安全的取钱
//两个人去银行取钱
public class UnsafeBank {

    public static void main(String[] args) {


    //账户
    Account account = new Account(100,"结婚基金");
    Drawing you = new Drawing(account,50,"你");
    Drawing girllfriend = new Drawing(account,100,"女朋友");

    you.start();
    girllfriend.start();

    }
}

//账户
class Account{

    int moeny;
    String name;

    public Account(int moeny,String name){
        this.moeny=moeny;
        this.name=name;
    }

}

//银行：模拟取款
class Drawing extends Thread{
    Account account;//账户
    //取了多少钱
    int drawingMoney;
    //现在手里有多少钱
    int nowMoney;

    public Drawing(Account account,int drawingMoney,String name){
        super(name);
        this.account=account;
        this.drawingMoney=drawingMoney;
    }

    //取钱


    @Override
    public void run() {
        //判断有没有钱
        if(account.moeny-drawingMoney<0){
            System.out.println(Thread.currentThread().getName()+"钱不够，取不了");
            return;
        }

        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        //卡内余额，=余额-你取得钱
        account.moeny=account.moeny-drawingMoney;
        //你手里的钱
        nowMoney=nowMoney+drawingMoney;
        System.out.println(account.name+"余额为："+account.moeny);
        //Thread.currentThread().getName()=this.money
        System.out.println(this.getName()+"手里的钱"+nowMoney);

    }
}

–3.线程不安全的集合

package com.Threadtest.syn;

import java.util.ArrayList;
import java.util.List;

//线程不安全的集合
public class UnsafeList {
    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        for (int i = 0; i <10000 ; i++) {
            new Thread(()->{
               list.add(Thread.currentThread().getName());
            }).start();
        }
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(list.size());
    }
}
  • 用synchronized解决买票负数问题
package com.Threadtest.syn;

//1.不安全的买票
//线程不安全 有负数
public class UnsafeBuyTicket {

   public static void main(String[] args) {
       BuyTicket station = new BuyTicket();

       new Thread(station,"苦逼的我").start();
       new Thread(station,"牛逼的你").start();
       new Thread(station,"傻逼的黄牛").start();

   }

}

class BuyTicket implements Runnable{

   //票
   private int ticketNums = 10;
   boolean flag = true;//外部停止方式
   @Override
   public void run() {
       //买票
       while(flag){
           buy();
       }
   }
   //synchronized 同步方法  锁的是this
   private synchronized void buy(){
       //判断是否有票
       if(ticketNums<=0){
           flag = false;
           return;
       }

       //模拟延时
       try {
           Thread.sleep(100);
       } catch (InterruptedException e) {
           e.printStackTrace();
       }

       //买票
       System.out.println(Thread.currentThread().getName()+"拿到"+ticketNums--);
   }

}
  • 用synchronized块解决银行取钱问题
package com.Threadtest.syn;

//不安全的取钱
//两个人去银行取钱
public class UnsafeBank {

    public static void main(String[] args) {


    //账户
    Account account = new Account(100,"结婚基金");
    Drawing you = new Drawing(account,50,"你");
    Drawing girllfriend = new Drawing(account,100,"女朋友");

    you.start();
    girllfriend.start();

    }
}

//账户
class Account{

    int moeny;
    String name;

    public Account(int moeny,String name){
        this.moeny=moeny;
        this.name=name;
    }

}

//银行：模拟取款
class Drawing extends Thread{
    Account account;//账户
    //取了多少钱
    int drawingMoney;
    //现在手里有多少钱
    int nowMoney;

    public Drawing(Account account,int drawingMoney,String name){
        super(name);
        this.account=account;
        this.drawingMoney=drawingMoney;
    }

    //取钱
    //synchronized默认锁是this

    @Override
    public void run() {

        synchronized (account){
            //判断有没有钱
            if(account.moeny-drawingMoney<0){
                System.out.println(Thread.currentThread().getName()+"钱不够，取不了");
                return;
            }

            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            //卡内余额，=余额-你取得钱
            account.moeny=account.moeny-drawingMoney;
            //你手里的钱
            nowMoney=nowMoney+drawingMoney;
            System.out.println(account.name+"余额为："+account.moeny);
            //Thread.currentThread().getName()=this.money
            System.out.println(this.getName()+"手里的钱"+nowMoney);

        }
        }

}
  • 用synchronized解决线程不安全的集合
package com.Threadtest.syn;

import java.util.ArrayList;
import java.util.List;

//线程不安全的集合
public class UnsafeList {
    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        for (int i = 0; i <10000 ; i++) {
            new Thread(()->{
                synchronized (list){
               list.add(Thread.currentThread().getName());
                }
            }).start();
        }
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(list.size());
    }
}
  • 安全的集合CopyOnWriteArrayList
package com.Threadtest.syn;

import java.util.concurrent.CopyOnWriteArrayList;

//测试JUC安全类型的集合
public class TestJUC {
   public static void main(String[] args) {
       CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<String>();
       for (int i = 0; i < 10000; i++) {
           new Thread(()->{
               list.add(Thread.currentThread().getName());
           }).start();
       }
       try {
           Thread.sleep(3000);
       } catch (InterruptedException e) {
           e.printStackTrace();
       }
       System.out.println(list.size());
   }
}
  • 死锁
    两个线程或多个线程相互等待对方的资源，都停止的情况
    在这里插入图片描述
    死锁问题
package com.Threadtest.syn;

//死锁：多个线程互相抱着对方的资源，然后形成僵持
public class DeadLock {
    public static void main(String[] args) {
        Makeup g1 = new Makeup(0,"小丽");
        Makeup g2 = new Makeup(1,"小明");
        g1.start();
        g2.start();
    }
}

//口红
class Lipstick{

}

//镜子
class Mirror{

}

class Makeup extends Thread{
    //需要的资源只有一份，用static来保证只有一份
    static Lipstick lipstick = new Lipstick();
    static Mirror mirror = new Mirror();
    int choice;//选择
    String girlName;//使用化妆品的人
    Makeup(int choice,String girlName){
        this.choice=choice;
        this.girlName=girlName;
    }
    @Override
    public void run() {
        //化妆
        try {
            makeup();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
    //化妆，互相持有对方的锁，就是需要拿到的资源
    private void makeup() throws InterruptedException {
        if(choice==0){
            synchronized (lipstick){
                System.out.println(this.girlName+"获得口红的锁");
                Thread.sleep(1000);
            synchronized (mirror){
                System.out.println(this.girlName+"获得镜子的锁");
            }
            }
            //这种情况下程序一直僵持着，互相都想要对方的东西，运行不能结束
        }else{
            synchronized (mirror){
                System.out.println(this.girlName+"获得镜子的锁");
            synchronized (lipstick){
                System.out.println(this.girlName+"获得口红的锁");
            }
            }
        }
    }
}

解决死锁问题

package com.Threadtest.syn;

//死锁：多个线程互相抱着对方的资源，然后形成僵持
public class DeadLock {
    public static void main(String[] args) {
        Makeup g1 = new Makeup(0,"小丽");
        Makeup g2 = new Makeup(1,"小明");
        g1.start();
        g2.start();
    }
}

//口红
class Lipstick{

}

//镜子
class Mirror{

}

class Makeup extends Thread{
    //需要的资源只有一份，用static来保证只有一份
    static Lipstick lipstick = new Lipstick();
    static Mirror mirror = new Mirror();
    int choice;//选择
    String girlName;//使用化妆品的人
    Makeup(int choice,String girlName){
        this.choice=choice;
        this.girlName=girlName;
    }
    @Override
    public void run() {
        //化妆
        try {
            makeup();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
    //化妆，互相持有对方的锁，就是需要拿到的资源
    private void makeup() throws InterruptedException {
        if(choice==0){
            synchronized (lipstick){
                System.out.println(this.girlName+"获得口红的锁");
                Thread.sleep(1000);
            }
            synchronized (mirror){
                System.out.println(this.girlName+"获得镜子的锁");
            }

        }else{
            synchronized (mirror){
                System.out.println(this.girlName+"获得镜子的锁");
            }
            synchronized (lipstick){
                System.out.println(this.girlName+"获得口红的锁");
            }
        }
    }
}
  • Lock锁
    在这里插入图片描述
package com.Threadtest.gaoji;

import java.util.concurrent.locks.ReentrantLock;

public class TestLock {
    public static void main(String[] args) {
        TestLock2 testLock2 = new TestLock2();
        new Thread(testLock2).start();
        new Thread(testLock2).start();
        new Thread(testLock2).start();
    }
}

class TestLock2 implements Runnable{
    int tickNums = 10;
    private final ReentrantLock lock = new ReentrantLock();
    @Override
    public void run() {
        lock.lock();
        try{
            while(true){
                if (tickNums>0){
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(tickNums--);
                }else{
                    break;
                }
            }

        }finally {
            lock.unlock();
        }

    }
}

  • sync和lock区别
    在这里插入图片描述

  • 线程协作
    生产者与消费者问题(我不会·这个)


package com.Threadtest.gaoji;

//测试：生产者消费者模型--》利用缓冲区解决：管程法

//生产者 消费者 产品 缓冲区
public class TestPC {
   public static void main(String[] args) {
       SynContainer synContainer = new SynContainer();
       new Productor(synContainer).start();
       new Consumer(synContainer).start();
   }
}
//生产者
class Productor extends Thread{
   SynContainer container;
   public Productor(SynContainer container){
       this.container=container;
   }
   //生产

   @Override
   public void run() {
       for (int i = 0; i < 100; i++) {
           container.push(new Chicken(i));
           System.out.println("生产了第"+i+"只鸡");
       }
   }
}
//消费者
class Consumer extends Thread{
   SynContainer container;
   public Consumer(SynContainer container){
       this.container=container;
   }
   //消费
   @Override
   public void run() {
       for (int i = 0; i < 100; i++) {
           System.out.println("一共消费了--》"+container.pop().id+"只鸡");
       }
   }
}
//产品
class Chicken{
   int id;//编号
   public Chicken(int id){
       this.id=id;
   }
}
//缓冲区
class SynContainer{
   //需要一个容器大小
   Chicken[] chickens = new Chicken[10];
   //容器计数器
   int count=0;
   //生产者放入产品
   public synchronized void push(Chicken chicken){
       //如果容器满了 就需要等待消费
       if(count==chickens.length){
           //通知消费者 生产等待
           try {
               this.wait();
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
       }
       //如果没有满 我们需要丢入产品
       chickens[count] = chicken;
       count++;
       //可以通知消费者消费了
       this.notifyAll();
   }
   //消费者消费产品
   public synchronized Chicken pop(){
       //判断是否消费
       if(count==0){
           try {
               this.wait();
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
       }
       //如果可以用消费
       count--;
       Chicken chicken = chickens[count];

       //吃完了，通知生产者
       this.notifyAll();
       return chicken;
   }
}
  • 信号灯法
package com.Threadtest.gaoji;

//测试生产者和消费者问题2：信号灯法 标识位解决
public class TestPC2 {
    public static void main(String[] args) {
        TV tv = new TV();
        new Player(tv).start();
        new Wacher(tv).start();
    }

}
//生产者--》演员
class Player extends Thread{
    TV tv;
    public Player(TV tv){
        this.tv=tv;
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            if(i%2==0){
                this.tv.play("快乐大本营播放中");
            }else{
                this.tv.play("抖音记录美好生活");
            }
        }
    }
}

//消费者--》观众
class Wacher extends Thread{
    TV tv;
    public Wacher(TV tv){
        this.tv=tv;
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            tv.watch();
        }
    }
}

//产品--》节目
class TV{
    //演员表演，观众等待 T
    //观众观看 演员等待 F
    String voice;//表演的节目
    boolean flag = true;

    //表演
    public synchronized void play(String voice){
        if(!flag){
            try {
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("演员表演了:"+voice);
        //通知观众观看
        this.notifyAll();//通知唤醒
        this.voice=voice;
        this.flag=!this.flag;
    }

    //观看
    public synchronized void watch(){
        if(flag){
            try {
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("观看了："+voice);
        //通知演员表演
        this.notifyAll();
        this.flag=!this.flag;
    }
}

可以想象成打电话

  • 线程池
package com.Threadtest.gaoji;

import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

//测试线程池
public class TestPool {

   public static void main(String[] args) {
       //1.创建服务 创建线程池
       //newFixedThreadPool:参数为线程池大小
       ExecutorService service = Executors.newFixedThreadPool(10);
       service.execute(new MyThread());
       service.execute(new MyThread());
       service.execute(new MyThread());
       service.execute(new MyThread());
       //2.关闭连接
       service.shutdown();
   }

}
class MyThread implements Runnable{

   @Override
   public void run() {
           System.out.println(Thread.currentThread().getName());

   }
}
  • 小结 实现方法
package com.Threadtest.gaoji;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class ThreadNew {
    public static void main(String[] args) {
        new MyThread1().start();

        new Thread(new MyThread2()).start();

        FutureTask<Integer> futureTask = new FutureTask(new MyThread3());
        new Thread(futureTask).start();
        try {
            Integer integer = futureTask.get();
            System.out.println(integer);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
}
//1.继承Thread类
class MyThread1 extends Thread{
    @Override
    public void run() {
        System.out.println("MyThread1");
    }
}
//2.实现Runnable接口
class MyThread2 implements Runnable{

    @Override
    public void run() {
        System.out.println("MyThread2");
    }
}
//3.实现Callable接口
class MyThread3 implements Callable{

    @Override
    public Integer call() throws Exception {
        System.out.println("MyThread3");
        return 100;
    }
}
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