Java多线程编程4--Lock的实例--实现生产者/消费者模式：一对一、多对多交替打印

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1、实现生产者/消费者模式：一对一交替打印

public class MyService {
    private ReentrantLock lock= new ReentrantLock();
    private Condition condition = lock.newCondition();
    private boolean hasValue = false;

    public void set() {
        try{
            lock.lock();
            while (hasValue == true) {
                condition.await();
            }
            System.out.println("----");
            hasValue = true;
            condition.signal();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    public void get() {
        try {
            lock.lock();
            while (hasValue == false) {
                condition.await();
            }
            System.out.println("****");
            hasValue = false;
            condition.signal();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}

public class MyThread1 extends Thread {
    private MyService service;
    public MyThread1(MyService service) {
        this.service = service;
    }
    @Override
    public void run() {
        for (int i=0; i<100; i++) {
            service.set();
        }
    }
}

public class MyThread2 extends Thread{
    private MyService service;
    public MyThread2(MyService service) {
        this.service = service;
    }
    @Override
    public void run() {
        for (int i=0; i<100; i++) {
            service.get();
        }
    }
}

public class Run {
    public static void main(String[] args) throws InterruptedException {
        MyService service = new MyService();
        MyThread1 a = new MyThread1(service);
        a.start();

        MyThread2 b = new MyThread2(service);
        b.start();

    }
}

2、实现生产者/消费者模式：多对多交替打印

public class MyService {
    private ReentrantLock lock= new ReentrantLock();
    private Condition condition = lock.newCondition();
    private boolean hasValue = false;

    public void set() {
        try{
            lock.lock();
            while (hasValue == true) {
                System.out.println("有可能--连续");  //就这里比上面的程序多了
                condition.await();
            }
            System.out.println("----");
            hasValue = true;
            condition.signal();   
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    public void get() {
        try {
            lock.lock();
            while (hasValue == false) {
                System.out.println("有可能**连续"); //就这里比上面的程序多了
                condition.await();
            }
            System.out.println("****");
            hasValue = false;
            condition.signal();   
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}

public class Run {
    public static void main(String[] args) throws InterruptedException {
        MyService service = new MyService();
        MyThread1[] threadA = new MyThread1[10];
        MyThread2[] threadB = new MyThread2[10];

        for (int i=0; i<10; i++) {
            threadA[i] = new MyThread1(service);
            threadB[i] = new MyThread2(service);
            threadA[i].start();
            threadB[i].start();
        }
    }
}

    根据第3章中的notifyAll()解决方案，可以使用signalAll()方法来解决。将MyService.java类中两处signal()代码改成signalAll()后，程序得到正确运行。
    从控制台打印的日志可以发现，运行后不再出现假死状态，假死问题被解决了。
    控制台中“----”和“****”是交替输出的，但是“有可能**连续”和“有可能--连续”却不是交替输出的，有时候出现连续打印的情况。原因是程序中使用了一个Condition对象，再结合signalAll()方法来唤醒所有的线程，那么唤醒的线程就有可能是同类，所以就出现连续打印“有可能**连续”或“有可能--连续”的情况了

Java多线程编程4--Lock的实例--实现生产者/消费者模式：一对一、多对多交替打印

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原文地址：http://blog.csdn.net/ochangwen/article/details/51340485