ReadWritelock

package com.shangguigu;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class ReadWritelockDemo {
    
    public static void main(String[] args) {
        MyCache myCache = new MyCache();
        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(()->{
                myCache.put(temp+"", temp);
            },String.valueOf(i)).start();
        }
        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(()->{
                myCache.get(temp+"");
            },String.valueOf(i)).start();
        }
    }
}
class MyCache{
    private volatile Map map = new HashMap();
    ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
    public void put(String key,Object value){
        readWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"写入数据"+key);
            //暂停一会线程
            try {
                TimeUnit.MICROSECONDS.sleep(300);
            } catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
            }
            map.put(key, value);
            System.out.println(Thread.currentThread().getName()+"写入数据完成");
        }catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            // TODO: handle finally clause
            readWriteLock.writeLock().unlock();
        }
        
    }
    
    public void get(String key){
        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"读取数据"+key);
            //暂停一会线程
            try {
                TimeUnit.MICROSECONDS.sleep(300);
            } catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
            }
            Object result = map.get(key);
            System.out.println(Thread.currentThread().getName()+"读取数据完成"+result);
        }catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            // TODO: handle finally clause
            readWriteLock.readLock().unlock();
        }
        
    }
}

执行结果：

0写入数据0
0写入数据完成
1写入数据1
1写入数据完成
2写入数据2
2写入数据完成
3写入数据3
3写入数据完成
4写入数据4
4写入数据完成
1读取数据1
2读取数据2
0读取数据0
3读取数据3
4读取数据4
3读取数据完成3
1读取数据完成1
0读取数据完成0
4读取数据完成4
2读取数据完成2