读写锁

package com.lock;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class ReadWriteLock {

    static Map<String,Object> map = new HashMap<String , Object>();
    static ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
    static Lock r = rwl.readLock();
    static Lock w = rwl.writeLock();

    public static final Object get(String key){
        r.lock();
        try{
            return map.get(key);
        }finally {
            r.unlock();
        }
    }

    public static final Object put(String key , Object value  ){
        w.lock();
        try {
            return map.put(key,value);
        }finally {
            w.unlock();
        }
    }

    public static final void clear(){
        w.lock();
        try{
            map.clear();
        }finally {
            w.unlock();
        }
    }

}