OS实验四_读者写者

ReadWriteLockTest：
package myPackage;

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

public class ReadWriteLockTest {
    public static void main(String[] args) {
        final Queue3 q3 = new Queue3();
        for (int i = 0; i < 3; i++) {
            new Thread() {
                public void run() {
                    while (true) {
                        q3.get();
                    }
                }
            }.start();
        }
        for (int i = 0; i < 3; i++) {
            new Thread() {
                public void run() {
                    while (true) {
                        q3.put(new Random().nextInt(10000));
                    }
                }
            }.start();
        }
    }
}


class Queue3 {
    private Object data = null;// 共享数据，只能有一个线程能写该数据，但可以有多个线程同时读该数据。
    private ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();

    public void get() {
        rwl.readLock().lock();// 上读锁，其他线程只能读不能写
        System.out.println(Thread.currentThread().getName()
                + " be ready to read data!");
        try {
            Thread.sleep((long) (Math.random() * 1000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName()
                + "have read data :" + data);
        rwl.readLock().unlock(); // 释放读锁，最好放在finnaly里面
    }

    public void put(Object data) {
        rwl.writeLock().lock();// 上写锁，不允许其他线程读也不允许写
        System.out.println(Thread.currentThread().getName()
                + " be ready to write data!");
        try {
            Thread.sleep((long) (Math.random() * 1000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        this.data = data;
        System.out.println(Thread.currentThread().getName()
                + " have write data: " + data);
        rwl.writeLock().unlock();// 释放写锁
    }
}