java多线程死锁 moira33的博客(7)

JDK1.5 中提供了多线程升级解决方案：

将同步Synchronized替换成显式Lock操作。

将Object中的wait，notify, notifyAll，替换成Condition对象。该对象可以通过Lock锁进行获取。

Lock 实现提供了比使用 synchronized方法和语句可获得的更广泛的锁定操作。此实现允许更灵活的结构，可以具有差别很大的属性，可以支持多个相关的Condition 对象。

Lock:替代了Synchronized

lock

unlock

newCondition()

Condition：替代了Object wait notify notifyAll

await();

signal();

signalAll();

public class ProducerConsumerDemo2 {
    public static void main(String[] args) {
        Resource2 r = new Resource2();
        new Thread(new Producer2(r)).start();
        new Thread(new Producer2(r)).start();
        new Thread(new Consumer2(r)).start();
        new Thread(new Consumer2(r)).start();
    }

}

class Resource2 {
    private String name;
    private int count = 1;
    private boolean flag = false;
    //  t1    t2
    private Lock lock = new ReentrantLock();
    private Condition condition_pro = lock.newCondition();
    private Condition condition_con = lock.newCondition();

    //Lock可以支持多个相关的 Condition 对象
    public void set(String name) throws InterruptedException {
        lock.lock();
        try {
            while (flag)
                condition_pro.await();//t1,t2
            this.name = name + "--" + count++;
            System.out.println(Thread.currentThread().getName() + "...生产者.." + this.name);
            flag = true;
            condition_con.signal();//唤醒对应等待线程
        } finally {
            lock.unlock();//释放锁的动作一定要执行。
        }
    }

    //  t3   t4  
    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 Producer2 implements Runnable {
    private Resource2 res;

    Producer2(Resource2 res) {
        this.res = res;
    }

    public void run() {
        while (true) {
            try {
                res.set("+商品+");
            } catch (InterruptedException e) {
            }
        }
    }
}

class Consumer2 implements Runnable {
    private Resource2 res;

    Consumer2(Resource2 res) {
        this.res = res;
    }

    public void run() {
        while (true) {
            try {
                res.out();
            } catch (InterruptedException e) {
            }
        }
    }
}

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