java 读写锁，

java 读写锁，

import java.util.Random;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * 读写锁 ,  读写 互斥 ,写写互斥  ,对于读 比 写频繁的时候 ,优势比较明显
 */
public class ReadWriteLockTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		final Queue q=new Queue();
		for (int i = 0; i < 3; i++) {
			new Thread(new Runnable(){
				@Override
				public void run() {
					while(true){
						q.get();
					}
				}

			}).start();

			new Thread(new Runnable(){
				@Override
				public void run() {
					while(true){
						q.put(new Random().nextInt());
					}
				}
			}).start();
		}

	}

}

class Queue{
	private Object data=null;  //共享数据,只能有一个线程能写该数据,但是可以有多个线程同时读该数据.
	ReadWriteLock rwl=new ReentrantReadWriteLock();
	public void get(){
		rwl.readLock().lock();
		System.out.println(Thread.currentThread().getName()+" be ready to read data!");
		try {
			Thread.sleep((long)Math.random()*1000);
		} catch (Exception e) {
			e.printStackTrace();
		}
		System.out.println(Thread.currentThread().getName()+" have read data"+data);
		rwl.readLock().unlock();
	}


	public void put(Object data){
		rwl.writeLock().lock();
		System.out.println(Thread.currentThread().getName()+" be ready to write data!");
		try {
			Thread.sleep((long)Math.random()*1000);
		} catch (Exception e) {
			e.printStackTrace();
		}
		this.data=data;
		System.out.println(Thread.currentThread().getName()+" have write data:"+data);
		rwl.writeLock().unlock();
	}

}