使用ReenTrantLock+Condition实现精准唤醒线程

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以前我们wait/notify notifyAll来实现线程的等待唤醒机制，可是notify 并不能精准地帮我唤醒我们想要唤醒的那个进程，这是可以使用ReenTrantLock+Condition来实现精准唤醒一个线程，每一个线程都会有一个Condition对象对唤醒。
直接上代码：

package com.richinfo.cn.reentrantlock;

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

/** 
 * @author : Allen(Wu Zhiwei)
 * @date 创建时间：2018年5月18日 上午11:33:28 
 * @version 1.0 
 * @parameter  
 * @since  
 * @return  
 */
public class MyService {
    private ReentrantLock lock = new ReentrantLock();
    private Condition ca = lock.newCondition();
    private Condition cb = lock.newCondition();

    public void awaitA(){
        try{
            lock.lock();
            System.out.println(Thread.currentThread().getName() + ",start waitA");
            ca.await();
            System.out.println(Thread.currentThread().getName() + ",end waitA");
        } catch (InterruptedException e){
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    public void awaitB(){
        try{
            lock.lock();
            System.out.println(Thread.currentThread().getName() + ",start waitB");
            cb.await();
            System.out.println(Thread.currentThread().getName() + ",end waitB");
        } catch (InterruptedException e){
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    public void singnalA(){
        try{
            lock.lock();
            ca.signal();
            System.out.println(Thread.currentThread().getName() + ",singnal A");
        } finally {
            lock.unlock();
        }
    }
}

测试类：

package com.richinfo.cn.reentrantlock;
/** 
 * @author : Allen(Wu Zhiwei)
 * @date 创建时间：2018年5月18日 上午11:31:11 
 * @version 1.0 
 * @parameter  
 * @since  
 * @return  
 */
public class Run {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        final MyService service = new MyService();
        Runnable ra = new Runnable(){

            @Override
            public void run() {
                // TODO Auto-generated method stub
                service.awaitA();

            }

        };
        Runnable rb = new Runnable(){

            @Override
            public void run() {
                // TODO Auto-generated method stub
                service.awaitB();

            }

        };
        Thread threadA =new Thread(ra);
        Thread threadB =new Thread(rb);
        threadA.setName("A");
        threadB.setName("B");
        threadA.start();
        threadB.start();
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        service.singnalA();
    }
}

控制台输出：
A,start waitA
B,start waitB
main,singnal A
A,end waitA