多线程（续）

1.死锁

package com.tian.thread;

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

//口红
class Lipstick{

}

//镜子
class Mirror{

}

class Makeup extends Thread{
    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，互相持有对方的债，就是需要拿到对方的资源
    private void makeup() throws InterruptedException {
        if (choice==0){
            synchronized (lipstick){//获得口红的债
                System.out.println(this.girlName+"获得口红的锁");
                Thread.sleep(1000);
                synchronized (mirror) {//一秒钟后获得镜子
                    System.out.println(this.girlName+"获得镜子的锁");
                }
            }
        }else {
            synchronized (mirror){//获得镜子的债
                System.out.println(this.girlName+"获得镜子的锁");
                Thread.sleep(2000);
                synchronized (lipstick) {//二秒钟后获得口红
                    System.out.println(this.girlName+"获得口红的锁");
                }
            }
        }
    }
}

解决方法：

package com.tian.thread;

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

//口红
class Lipstick{

}

//镜子
class Mirror{

}

class Makeup extends Thread{
    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，互相持有对方的债，就是需要拿到对方的资源
    private void makeup() throws InterruptedException {
        if (choice==0){
            synchronized (lipstick){//获得口红的债
                System.out.println(this.girlName+"获得口红的锁");
                Thread.sleep(1000);

            }
            synchronized (mirror) {//一秒钟后获得镜子
                System.out.println(this.girlName+"获得镜子的锁");
            }
        }else {
            synchronized (mirror){//获得镜子的债
                System.out.println(this.girlName+"获得镜子的锁");
                Thread.sleep(2000);

            }
            synchronized (lipstick) {//二秒钟后获得口红
                System.out.println(this.girlName+"获得口红的锁");
            }
        }
    }
}

产生死锁的四个必要条件：

互斥条件：一个资源每次只能被一个进程使用
请求与保持条件：一个进程因请求资源而阻塞时，对已获得的资源保持不放
不剥夺条件：进程已获得的资源，在未使用完之前，不能强行剥夺
循环等待条件：若干进程之间形成一种头尾相接的循环等待资源关系

2.Lock锁

package com.tian.gaoji;

import java.util.concurrent.locks.ReentrantLock;

//测试Lock锁
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 ticketNums = 10;

    //定义Lock锁
    ReentrantLock lock = new ReentrantLock();


    @Override
    public void run() {
        while (true){
            try{
                lock.lock();//加锁
                if (ticketNums>0){
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(ticketNums--);
                }else {
                    break;
                }
            }finally {
                //解锁
                lock.unlock();
            }
        }
    }
}

3.生产者消费问题

3.1管程法

package com.tian.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 container = new SynContainer();

        new Productor(container).start();
        new Consumer(container).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"+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("消费了-->"+container.pop().id+"只鸡");
        }
    }
}

//产品
class  Chicken{
    int id;//产品编号

    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，就需要等待消费者消费
        if (count==chickens.length){
            //通知消费者消费，生产等待
        }

        //如果没有满，我们就需要丢入产品
        chickens[count]=chicken;
        count++;

        //可以通知消费者消费了
    }

    //消费者消费产品
    public synchronized Chicken pop(){
        //判断能否消费
        if (count==0){
            //等待生产者生产，消费者等待
        }
        //如果可以消费
        count--;
        Chicken chicken = chickens[count];
        //吃完了，通知生产者生产
        return chicken;
    }
}

3.2信号灯法

package com.tian.gaoji;

//测试生产者消费者问题2：信号灯法，标志位解决
public class TestPC2 {
    public static void main(String[] args) {
        TV tv = new TV();
        new Player(tv).start();
        new Watcher(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 Watcher extends Thread{
    TV tv;
    public Watcher(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;

    }
}

4.线程池

package com.tian.gaoji;

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);

        //执行
        service.execute(new MyThread());
        service.execute(new MyThread());
        service.execute(new MyThread());
        service.execute(new MyThread());

        //2.关闭链接
        service.shutdown();
    }
}
class MyThread implements Runnable{

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

5.总结

package com.tian.gaoji;

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

//回顾总结线程的创建
public class ThreadNew {
    public static void main(String[] args) {
        new MyThread1().start();

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

        FutureTask<Integer> futureTask = new FutureTask<Integer>(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<Integer>{
    @Override
    public Integer call() throws Exception {
        System.out.println("MyThread3");
        return 100;
    }
}

posted @ 2025-07-28 19:14 A那就算了吧阅读(6) 评论(0) 收藏举报

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ths-java

多线程（续）

多线程（续）

1.死锁

2.Lock锁

3.生产者消费问题

3.1管程法

3.2信号灯法

4.线程池

5.总结

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