多线程和并发库应用十二--Condition

编程入门行业动态更新时间:2024-10-24 22:20:16

我们知道在线程的同步时可以使一个线程阻塞而等待一个信号，同时放弃锁使其他线程可以能竞争到锁。在synchronized中我们可以使用Object的wait()和notify方法实现这种等待和唤醒，但是在Lock中怎么实现这种wait和notify呢？答案是Condition
前面用等待唤醒的方式实现了a调用10次b调用20次，a调用10次b调用20次重复50次。那么a 调用10次 b调用20次 c 调用30次，a 调用10次 b调用20次 c 调用30次重复50次怎么实现呢。

public class Business {
     Lock lock=new ReentrantLock();
     Condition condition1=lock.newCondition();
     Condition condition2 =lock.newCondition();
     Condition condition3 =lock.newCondition();
    private  int bShouldSub=1;
    public   void sub1(int i){
        lock.lock();
        try {
            while (bShouldSub!=1){
                try {
                    condition1.await();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            for (int j=1;j<=5;j++){
                System.out.println("sub1 sequece "+i+" loop for "+j);
            }
            bShouldSub=2;
            condition2.signal();
        }finally {
            lock.unlock();
        }

    }
    public   void sub2(int i) {
        lock.lock();
        try {
            while (bShouldSub!=2) {
                try {
                  //  this.wait();
                    condition2.await();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            for (int j = 1; j <= 20; j++) {
                System.out.println("main sequece " + i + " loop for " + j);
            }
            bShouldSub=3;
            condition3.signal();
        }finally {
            lock.unlock();
        }
    }
    public   void sub3(int i){
        lock.lock();
        try {
            while (bShouldSub!=3){
                try {
                    condition3.await();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            for (int j=1;j<=30;j++){
                System.out.println("sub3 sequece "+i+" loop for "+j);
            }
            bShouldSub=1;
            condition1.signal();
        }finally {
            lock.unlock();
        }

    }
}

主函数这里写代码片

public class Main {
    public  static  void main(String[] args){
        final Business bs=new Business();
        new Thread(new Runnable() {
            public void run() {
                for (int i=1;i<=50;i++){
                    bs.sub1(i);
                }
            }
        }).start();
        new Thread(new Runnable() {
            public void run() {
                for (int i=1;i<=50;i++){
                    bs.sub2(i);
                }
            }
        }).start();

        new Thread(new Runnable() {
            public void run() {
                for (int i=1;i<=50;i++){
                    bs.sub3(i);
                }
            }
        }).start();
    }
}