只有读读是并发的，

其它读写，写写，写读都是互斥的哟。

package demo.thread;

import java.util.concurrent.locks.ReentrantReadWriteLock;

public class MyService {
	
	private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
	public void read() {
		try {
			try {
				lock.readLock().lock();
				System.out.println("Get read lock" + Thread.currentThread().getName() 
						+ " " + System.currentTimeMillis());
				Thread.sleep(1000L);
			} finally {
				lock.readLock().unlock();
			}
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
	
	public void write() {
		try {
			try {
				lock.writeLock().lock();
				System.out.println("Get read lock" + Thread.currentThread().getName() 
						+ " " + System.currentTimeMillis());
				Thread.sleep(1000L);
			} finally {
				lock.writeLock().unlock();
			}
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	

}

package demo.thread;

public class ThreadA extends Thread {
	private MyService service;
	
	public ThreadA(MyService service) {
		super();
		this.service = service;
	}
	
	@Override
	public void run() {
		service.read();
	}

}

package demo.thread;

public class ThreadB extends Thread {
	private MyService service;
	
	public ThreadB(MyService service) {
		super();
		this.service = service;
	}
	
	@Override
	public void run() {
		service.write();;
	}

}

package demo.thread;

public class Run  {

	public static void main(String[] args)  throws InterruptedException {
		// TODO Auto-generated method stub
		final MyService service = new MyService();
		
		ThreadA a = new ThreadA(service);
		a.setName("A");
		a.start();
		
		Thread.sleep(1000);
		
		ThreadB b = new ThreadB(service);
		b.setName("B");
		b.start();
		

	}

}