美文网首页Java
Java 多线程 线程间通信-等待唤醒机制

Java 多线程 线程间通信-等待唤醒机制

作者: 一亩三分甜 | 来源:发表于2019-08-19 01:53 被阅读0次

    线程间通讯:其实就是多个线程在操作同一个资源，但是操作的动作不同。

    class Res
{
    String name;
    String sex;
}
class Input implements Runnable
{
    private Res r;
    private int x = 0;
    Input(Res r)
    {
        this.r = r;
    }
    public void run()
    {
        while (true)
        {
            synchronized (r)
            {
                if (x==0)
                {
                    r.name = "mike";
                    r.sex = "man";
                }
                else
                {
                    r.name = "丽丽";
                    r.sex = "女女女女女女";
                }
                x = (x+1)%2;
            }
        }
    }
}
class Output implements Runnable
{
    private Res r;
    Output(Res r)
    {
        this.r = r;
    }
    public void run()
    {
        while (true)
        {
            synchronized (r)
            {
                System.out.println(r.name+"....."+r.sex);
            }
        }
    }
}
public class InputOutputDemo {
    public static void main(String[] args) {
         Res r = new Res();
         Input in = new Input(r);
         Output out = new Output(r);

         Thread t1 = new Thread(in);
         Thread t2 = new Thread(out);

         t1.start();
         t2.start();
    }
}
//输出正常
mike.....man
mike.....man
mike.....man
丽丽.....女女女女女女
丽丽.....女女女女女女
丽丽.....女女女女女女

    wait();notify();notifyAll();都使用在同步中，因为要对持有监视器(锁)的线程操作。所以要使用在同步中，因为只有同步才具有锁。

    为什么这些操作线程的方法要定义object类中呢？
    因为这些方法在操作同步中线程时，都必须要标识他们所操作线程持有的锁，只有同一个锁上的被等待线程，可以被同一个锁上notify唤醒。不可以对不同锁中的线程进行唤醒。
    也就是说，等待和唤醒必须是同一个锁。
    而锁可以是任意对象，所以可以被任意对象调用的方法定义Object类中。

    class Res
{
    String name;
    String sex;
    boolean flag = false;
}
class Input implements Runnable
{
    private Res r;
    private int x = 0;
    Input(Res r)
    {
        this.r = r;
    }
    public void run()
    {
        while (true)
        {
            synchronized (r)
            {
                if (r.flag)
                    try { r.wait(); }catch (InterruptedException e){}
                if (x==0)
                {
                    r.name = "mike";
                    r.sex = "man";
                }
                else
                {
                    r.name = "丽丽";
                    r.sex = "女女女女女女";
                }
                x = (x+1)%2;
                r.flag = true;
                r.notify();
            }
        }
    }
}
class Output implements Runnable
{
    private Res r;
    Output(Res r)
    {
        this.r = r;
    }
    public void run()
    {
        while (true)
        {
            synchronized (r)
            {
                if (!r.flag)
                    try { r.wait(); }catch (InterruptedException e){}
                System.out.println(r.name+"....."+r.sex);
                r.flag = false;
                r.notify();
            }
        }
    }
}
public class InputOutputDemo {
    public static void main(String[] args) {
         Res r = new Res();
         Input in = new Input(r);
         Output out = new Output(r);

         Thread t1 = new Thread(in);
         Thread t2 = new Thread(out);

         t1.start();
         t2.start();
    }
}
//输出
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女

    优化代码为同步函数形式

    class Res0 {
    private String name;
    private String sex;
    private boolean flag = false;

    public synchronized void set(String name, String sex) {
        if (flag)
            try { this.wait(); } catch (InterruptedException e) { }
        this.name = name;
        this.sex = sex;
        flag = true;
        this.notify();
    }

    public synchronized void out() {
        if (!flag)
            try { this.wait(); } catch (InterruptedException e) {}
        System.out.println(name + "....." + sex);
        flag = false;
        this.notify();
    }
}

class Input0 implements Runnable {
    private Res0 r;
    private int x = 0;

    Input0(Res0 r) {
        this.r = r;
    }

    public void run() {
        while (true) {
            if (x == 0) {
                r.set("mike", "man");
            } else {
                r.set("丽丽", "女女女女女女");
            }
            x = (x + 1) % 2;
        }
    }
}

class Output0 implements Runnable {
    private Res0 r;

    Output0(Res0 r) {
        this.r = r;
    }

    public void run() {
        while (true) {
            r.out();
        }
    }
}

public class InputOutputDemo0 {
    public static void main(String[] args) {
        Res0 r = new Res0();
        new Thread(new Input0(r)).start();
        new Thread(new Output0(r)).start();
    }
}
//输出
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女
mike.....man
丽丽.....女女女女女女

    多个生产者和消费者情况

    class Resource
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    public synchronized void set(String name)
    {
        while(flag)
            try { this.wait(); }catch (InterruptedException e){}
        this.name = name+"--"+count++;
        System.out.println(Thread.currentThread().getName()+".....生产者"+this.name);
        flag = true;
        this.notifyAll();
    }
    public synchronized void out()
    {
        while(!flag)
            try { this.wait(); }catch (InterruptedException e){}
        System.out.println(Thread.currentThread().getName()+"......消费者"+this.name);
        flag = false;
        this.notifyAll();
    }
}
class Producer implements Runnable {
    private Resource res;

    Producer(Resource res)
    {
        this.res = res;
    }
    public void run()
    {
        while (true)
//        for (int i = 0;i<1000;i++)
        res.set("+商品+");
    }
}
class Consumer implements Runnable
{
    private Resource res;
    Consumer(Resource res)
    {
        this.res = res;
    }
    public void  run()
    {
        while (true)
//        for (int i = 0;i<1000;i++)
        res.out();
    }
}
public class ProducerConsumerDemo {
    public static void main(String[] args) {
        Resource res = new Resource();
        Producer p1 = new Producer(res);
        Consumer c1 = new Consumer(res);
        Thread t1 = new Thread(p1);
        Thread t2 = new Thread(p1);
        Thread t3 = new Thread(c1);
        Thread t4 = new Thread(c1);

        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}
为什么要定义while判断标记。
原因:让被唤醒的线程再一次判断标记。
为什么定义nofigyAll,因为需要唤醒对方线程。因为只用notify,容易出现只唤醒本方线程的情况，导致程序中的所有线程都等待。

    JDK1.5.0中提供了多线程升级解决方案。将同步Synchronized替换成显示Lock操作。将Object中的wait,notify,notifyAll,替换了Condition对象。该对象可以Lock锁进行获取。该示例中，实现了本方只唤醒本方操作。

    import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class Resource0
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();
    public void set(String name)throws InterruptedException
    {
        lock.lock();
        try{
            while(flag)
                condition.await();
            this.name = name+"--"+count++;
            System.out.println(Thread.currentThread().getName()+".....生产者"+this.name);
            flag = true;
            condition.signal();
        }
        finally {
            lock.unlock();
        }
    }
    public void out() throws InterruptedException
    {
        lock.lock();
        try {
            while(!flag)
                condition.await();
            System.out.println(Thread.currentThread().getName()+"......消费者"+this.name);
            flag = false;
            condition.signal();
        }
        finally {
            lock.unlock();
        }
    }
}
class Producer0 implements Runnable {
    private Resource0 res;

    Producer0(Resource0 res)
    {
        this.res = res;
    }
    public void run()
    {
        while (true)
            try{
                //        for (int i = 0;i<1000;i++)
                res.set("+商品+");
            }
            catch (InterruptedException e)
            {

            }
    }
}
class Consumer0 implements Runnable
{
    private Resource0 res;
    Consumer0(Resource0 res)
    {
        this.res = res;
    }
    public void  run()
    {
        while (true)
            try {
                //        for (int i = 0;i<1000;i++)
                res.out();
            }catch (InterruptedException e)
            {

            }

    }
}
public class ProducerConsumerDemo0 {
    public static void main(String[] args) {
        Resource0 res = new Resource0();
        Producer0 p1 = new Producer0(res);
        Consumer0 c1 = new Consumer0(res);
        Thread t1 = new Thread(p1);
        Thread t2 = new Thread(p1);
        Thread t3 = new Thread(c1);
        Thread t4 = new Thread(c1);

        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}
//输出:全部唤醒，程序无法结束
    0.gif

    condition.signal()唤醒本方线程，造成相互等待程序无法结束。

    import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class Resource0
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();
    public void set(String name)throws InterruptedException
    {
        lock.lock();
        try{
            while(flag)
                condition.await();
            this.name = name+"--"+count++;
            System.out.println(Thread.currentThread().getName()+".....生产者"+this.name);
            flag = true;
            condition.signalAll();
        }
        finally {
            lock.unlock();
        }
    }
    public void out() throws InterruptedException
    {
        lock.lock();
        try {
            while(!flag)
                condition.await();
            System.out.println(Thread.currentThread().getName()+"......消费者"+this.name);
            flag = false;
            condition.signalAll();
        }
        finally {
            lock.unlock();
        }
    }
}
class Producer0 implements Runnable {
    private Resource0 res;

    Producer0(Resource0 res)
    {
        this.res = res;
    }
    public void run()
    {
        while (true)
            try{
                //        for (int i = 0;i<1000;i++)
                res.set("+商品+");
            }
            catch (InterruptedException e)
            {

            }
    }
}
class Consumer0 implements Runnable
{
    private Resource0 res;
    Consumer0(Resource0 res)
    {
        this.res = res;
    }
    public void  run()
    {
        while (true)
            try {
                //        for (int i = 0;i<1000;i++)
                res.out();
            }catch (InterruptedException e)
            {

            }

    }
}
public class ProducerConsumerDemo0 {
    public static void main(String[] args) {
        Resource0 res = new Resource0();
        Producer0 p1 = new Producer0(res);
        Consumer0 c1 = new Consumer0(res);
        Thread t1 = new Thread(p1);
        Thread t2 = new Thread(p1);
        Thread t3 = new Thread(c1);
        Thread t4 = new Thread(c1);

        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}
//输出正常
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class Resource0
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    private Lock lock = new ReentrantLock();
    private Condition condition_pro = lock.newCondition();
    private Condition condition_con = lock.newCondition();

//    private Condition condition = lock.newCondition();

    public void set(String name)throws InterruptedException
    {
        lock.lock();
        try{
            while(flag)
                condition_pro.await();
            this.name = name+"--"+count++;
            System.out.println(Thread.currentThread().getName()+"...生产者"+this.name);
            flag = true;
            condition_con.signal();
        }
        finally {
            lock.unlock();
        }
    }
    public void out() throws InterruptedException
    {
        lock.lock();
        try {
            while(!flag)
                condition_con.await();
            System.out.println(Thread.currentThread().getName()+"..消费者"+this.name);
            flag = false;
            condition_pro.signal();
        }
        finally {
            lock.unlock();
        }
    }
}
class Producer0 implements Runnable {
    private Resource0 res;

    Producer0(Resource0 res)
    {
        this.res = res;
    }
    public void run()
    {
        while (true)
            try{
                //        for (int i = 0;i<1000;i++)
                res.set("+商品+");
            }
            catch (InterruptedException e)
            {

            }
    }
}
class Consumer0 implements Runnable
{
    private Resource0 res;
    Consumer0(Resource0 res)
    {
        this.res = res;
    }
    public void  run()
    {
        while (true)
            try {
                //        for (int i = 0;i<1000;i++)
                res.out();
            }catch (InterruptedException e)
            {

            }

    }
}
public class ProducerConsumerDemo0 {
    public static void main(String[] args) {
        Resource0 res = new Resource0();
        Producer0 p1 = new Producer0(res);
        Consumer0 c1 = new Consumer0(res);
        Thread t1 = new Thread(p1);
        Thread t2 = new Thread(p1);
        Thread t3 = new Thread(c1);
        Thread t4 = new Thread(c1);

        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}
//输出正常

    停止线程

    stop方法已经过时。
    如何停止线程？
    只有一种，run方法结束。开启多线程运行，运行代码通常是循环结构。只要控制住循环，就可以让run方法结束，也就是线程结束。

    特殊情况:当线程处于了冻结状态。
    就不会读取到标记，那么线程就不会结束。
    当没有指定的方式让冻结的线程恢复到运行状态时，这时需要对冻结状态进行清除。
    强制让线程恢复到运行状态中来。这样就可以操作标记让线程结束。
    Thread类提供了该方法interrupt();

    class  StopThread implements Runnable
{
    private Boolean flag = true;
    public void run()
    {
       while (flag)
       {
           System.out.println(Thread.currentThread().getName()+"...run");
       }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
public class StopThreadDemo {
    public static void main(String[] args) {
        StopThread st = new StopThread();

        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);

        t1.start();
        t2.start();

        int num = 0;

        while (true)
        {
            if (num++ == 60)
            {
                st.changeFlag();
                break;
            }
            System.out.println(Thread.currentThread().getName()+"......"+num);
        }
    }
}
//输出正常:num到60,改变标记flag,结束循环，结束打印,结束线程。
...
main......50
Thread-0...run
main......51
Thread-1...run
main......52
Thread-0...run
main......53
Thread-1...run
main......54
Thread-0...run
main......55
Thread-1...run
main......56
main......57
main......58
Thread-0...run
Thread-0...run
main......59
Thread-1...run
main......60
Thread-0...run
Thread-1...run

    线程无法中断

    class  StopThread0 implements Runnable
{
    private Boolean flag = true;
    public synchronized void run()
    {
        while (flag)
        {
            try{
                wait();
            }catch (InterruptedException e)
            {
                System.out.println(Thread.currentThread().getName()+"...run"+e.toString());
            }
            System.out.println(Thread.currentThread().getName()+"...run");
        }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
public class StopThreadDemo0 {
    public static void main(String[] args) {
        StopThread0 st = new StopThread0();

        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);

        t1.start();
        t2.start();

        int num = 0;

        while (true)
        {
            if (num++ == 60)
            {
                st.changeFlag();
                break;
            }
            System.out.println(Thread.currentThread().getName()+"......"+num);
        }
        System.out.println(Thread.currentThread().getName()+"over");
    }
}
//输出:程序无法结束
    2.gif 
    class  StopThread0 implements Runnable
{
    private Boolean flag = true;
    public synchronized void run()
    {
        while (flag)
        {
            try{
                wait();
            }catch (InterruptedException e)
            {
                System.out.println(Thread.currentThread().getName()+"...run"+e.toString());
            }
            System.out.println(Thread.currentThread().getName()+"...run");
        }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
public class StopThreadDemo0 {
    public static void main(String[] args) {
        StopThread0 st = new StopThread0();

        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);

        t1.start();
        t2.start();

        int num = 0;

        while (true)
        {
            if (num++ == 60)
            {
//                st.changeFlag();
                t1.interrupt();
                t2.interrupt();
                break;
            }
            System.out.println(Thread.currentThread().getName()+"......"+num);
        }
        System.out.println(Thread.currentThread().getName()+"over");
    }
}
//输出:程序无法结束
    4.gif

    程序结束

    class  StopThread0 implements Runnable
{
    private Boolean flag = true;
    public synchronized void run()
    {
        while (flag)
        {
            try{
                wait();
            }catch (InterruptedException e)
            {
                System.out.println(Thread.currentThread().getName()+"...run"+e.toString());
                flag = false;
            }
            System.out.println(Thread.currentThread().getName()+"...run");
        }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
public class StopThreadDemo0 {
    public static void main(String[] args) {
        StopThread0 st = new StopThread0();

        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);

        t1.start();
        t2.start();

        int num = 0;

        while (true)
        {
            if (num++ == 60)
            {
//                st.changeFlag();
                t1.interrupt();
                t2.interrupt();
                break;
            }
            System.out.println(Thread.currentThread().getName()+"......"+num);
        }
        System.out.println(Thread.currentThread().getName()+"over");
    }
}
//输出正常
main......50
main......51
main......52
main......53
main......54
main......55
main......56
main......57
main......58
main......59
main......60
mainover
Thread-0...runjava.lang.InterruptedException
Thread-0...run
Thread-1...runjava.lang.InterruptedException
Thread-1...run

    守护线程

    class  StopThread1 implements Runnable
{
    private Boolean flag = true;
    public void run()
    {
        while (flag)
        {
            System.out.println(Thread.currentThread().getName()+"...run");
        }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
public class StopThreadDemo1 {
    public static void main(String[] args) {
        StopThread1 st = new StopThread1();

        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);

        t1.setDaemon(true);
        t2.setDaemon(true);
        t1.start();
        t2.start();

        int num = 0;

        while (true)
        {
            if (num++ == 60)
            {
//                st.changeFlag();
//                t1.interrupt();
//                t2.interrupt();
                break;
            }
            System.out.println(Thread.currentThread().getName()+"......"+num);
        }
        System.out.println(Thread.currentThread().getName()+"over");
    }
}
//输出
Thread-0...run
main......58
Thread-1...run
main......59
Thread-0...run
Thread-0...run
main......60
Thread-1...run
Thread-0...run
Thread-0...run
Thread-0...run
Thread-1...run
Thread-1...run
Thread-0...run
Thread-0...run
Thread-1...run
Thread-0...run
mainover
Thread-1...run
Thread-0...run
Thread-1...run
Thread-0...run
Thread-1...run
Thread-0...run
Thread-1...run
Thread-0...run
Thread-1...run
Thread-0...run

    join方法:当A线程执行到了B线程的.join()方法时，A就会等待。等B线程都执行完，A才会执行。join可以用来临时加入线程执行。

    class Demo6 implements Runnable
{
    public void run()
    {
        for (int x = 0;x<60;x++)
        {
            System.out.println(Thread.currentThread().getName()+"....."+x);
        }
    }
}
public class JoinDemo {
    public static void main(String[] args) throws InterruptedException
    {
       Demo6 d = new Demo6();
       Thread t1 = new Thread(d);
       Thread t2 = new Thread(d);
       t1.start();
       t1.join();
       t2.start();

       for (int x=0;x<70;x++)
       {
           System.out.println("main......"+x);
       }
       System.out.println("over");
    }
}
//输出:t1线程执行完才回到主线程
...
Thread-0.....55
Thread-0.....56
Thread-0.....57
Thread-0.....58
Thread-0.....59
Thread-1.....0
Thread-1.....1
Thread-1.....2
...

    优先级

    class Demo7 implements Runnable
{
    public void run()
    {
        for (int x = 0;x<60;x++)
        {
            System.out.println(Thread.currentThread().toString()+"....."+x);
        }
    }
}
public class PriorityYeildDemo {
    public static void main(String[] args) throws InterruptedException
    {
        Demo7 d = new Demo7();
        Thread t1 = new Thread(d);
        Thread t2 = new Thread(d);
        t1.start();
        t1.setPriority(Thread.MAX_PRIORITY);
        t2.start();

        for (int x=0;x<70;x++)
        {
            System.out.println("main......"+x);
        }
        System.out.println("over");
    }
}
//输出:优先级为10
Thread[Thread-1,5,main].....0
Thread[Thread-0,10,main].....0
Thread[Thread-1,5,main].....1
Thread[Thread-0,10,main].....1
Thread[Thread-1,5,main].....2
Thread[Thread-0,10,main].....2
...
Thread[Thread-1,5,main].....57
Thread[Thread-0,10,main].....56
Thread[Thread-1,5,main].....58
Thread[Thread-0,10,main].....57
Thread[Thread-1,5,main].....59
Thread[Thread-0,10,main].....58
Thread[Thread-0,10,main].....59

    yield

    class Demo7 implements Runnable
{
    public void run()
    {
        for (int x = 0;x<60;x++)
        {
            System.out.println(Thread.currentThread().toString()+"....."+x);
            Thread.yield();
        }
    }
}
public class PriorityYeildDemo {
    public static void main(String[] args) throws InterruptedException
    {
        Demo7 d = new Demo7();
        Thread t1 = new Thread(d);
        Thread t2 = new Thread(d);
        t1.start();
        t2.start();

        for (int x=0;x<70;x++)
        {
            System.out.println("main......"+x);
        }
        System.out.println("over");
    }
}
//输出:中断当前线程，线程交替更频繁
Thread[Thread-0,5,main].....0
Thread[Thread-0,5,main].....1
Thread[Thread-0,5,main].....2
Thread[Thread-1,5,main].....0
Thread[Thread-0,5,main].....3
Thread[Thread-1,5,main].....1
Thread[Thread-0,5,main].....4
Thread[Thread-1,5,main].....2
Thread[Thread-0,5,main].....5
Thread[Thread-1,5,main].....3
Thread[Thread-0,5,main].....6

    多线程的使用:匿名内部类，继承或实现封装

    public class ThreadTest {
    public static void main(String[] args) {
        new Thread(){
            public void run()
            {
                for (int x = 0;x <100;x++)
                {
                    System.out.println(Thread.currentThread().toString()+"..."+x);
                }
            }
        }.start();

        for (int x = 0;x <100;x++)
        {
            System.out.println(Thread.currentThread().toString()+"..."+x);
        }

        Runnable r = new Runnable(){
            public void  run()
            {
                for (int x = 0;x <100;x++)
                {
                    System.out.println(Thread.currentThread().toString()+"..."+x);
                }
            }
        };
        new Thread(r).start();
    }
}
//封装
class Demo8 extends Thread
{
    public void run()
    {
        for (int x = 0;x <100;x++)
        {
            System.out.println(Thread.currentThread().toString()+"..."+x);
        }
    }
}

    相关文章

      网友评论

        本文标题：Java 多线程 线程间通信-等待唤醒机制

        本文链接：https://www.haomeiwen.com/subject/nqmdsctx.html

        延伸阅读

        深度阅读

        • 您也可以注册成为美文阅读网的作者，发表您的原创作品、分享您的心情！

        栏目导航

        热点阅读

        Java

        关于我们|服务条款|联系我们|Java 多线程 线程间通信-等待唤醒机制|投稿指南|网站地图|RSS订阅|排版工具|手机版

        提供经典美文摘抄,优美散文欣赏,现代诗歌精选,短篇小说,心情随笔,表白情书范文,故事会在线阅读欣赏

        Copyright © 2014-2023 Haomeiwen.com All Rights Reserved. 好美文阅读网 版权所有

        备案信息：桂公网安备 45052102000051号 · 桂ICP备13007215号-3

        本站所收录作品、热点评论等信息部分来源互联网，目的只是为了系统归纳学习和传递资讯

        所有作品版权归原创作者所有，与本站立场无关，如不慎侵犯了你的权益，请联系我们告知，我们将做删除处理！