键盘Java侠 2017-04-19 08:18 采纳率: 0%
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求教大神,我上了读写锁以后,创建了一条写线程四条读线程,可是读线程的运行依旧是阻塞的

这个是上读写锁的部分

 public class LockMap {

    private static HashMap<String,Object> map=new HashMap<String, Object>();
    private static ReentrantReadWriteLock lock=new ReentrantReadWriteLock();
    private static Lock read=lock.readLock();
    private static Lock write=lock.writeLock();

    public Object get(String key) throws InterruptedException {
        read.lock();
        try{
            Object obj=map.get(key);
            return obj;
        }finally {
            read.unlock();
        }
    }

    public void put(String key,Object value) throws InterruptedException {
        write.lock();
        try{
            map.put(key,value);
        }finally {
            write.unlock();
        }
    }

}

这是创建线程运行的部分

 public class LockMapTest {

    private static SimpleDateFormat format=new SimpleDateFormat("HH:mm:ss:sss");
    private static LockMap map=new LockMap();

    public static void main(String[] args) throws InterruptedException {
        new Thread(new Runner("w"),"Write-Thread1").start();
        new Thread(new Runner("r"),"Read-Thread1").start();
        new Thread(new Runner("r"),"Read-Thread2").start();
        new Thread(new Runner("r"),"Read-Thread3").start();
        new Thread(new Runner("r"),"Read-Thread4").start();
    }

    public static class Runner implements Runnable{

        private String readWrite;

        public Runner(String readWrite){
            this.readWrite=readWrite;
        }
        public void run() {
            while (true){
                if ("w".equals(readWrite)){
                    try {
                        System.out.println(format.format(new Date())+" Current thread "+Thread.currentThread().getName()+" writing ");
                        map.put("first",UUID.randomUUID().toString());
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }else if ("r".equals(readWrite)){
                    try {
                        System.out.println(format.format(new Date())+" Current thread "+Thread.currentThread().getName()+" get value "+map.get("first"));
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

}

运行以后,线程运行效果图
图片说明

  • 写回答

4条回答 默认 最新

  • 键盘Java侠 2017-04-19 08:25
    关注

    运行以后,四条读线程总是只有一条线程能运行,并不能同时运行,这是怎么回事吖

    评论

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