package readwrite;

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;

/**

* @author ： CodeWater

* @create ：2022-06-03-18:02

* @Function Description ：演示读写锁

*/

class MyCache {

//创建map集合

private volatile Map<String , Object> map = new HashMap<>();

//创建读写锁对象

private ReadWriteLock rwLock = new ReentrantReadWriteLock();

//放数据

public void put( String key , Object value ){

//添加写锁

rwLock.writeLock().lock();

try{

System.out.println(Thread.currentThread().getName()+" 正在写操作"+key);

//暂停一会(千分之一毫秒)

TimeUnit.MICROSECONDS.sleep( 300 );

//放数据

map.put( key , value );

System.out.println(Thread.currentThread().getName()+" 写完了"+key);

}catch( InterruptedException e ){

e.printStackTrace();

}finally{

//释放写锁

rwLock.writeLock().unlock();

}

}

//取数据

public Object get( String key ){

//添加读锁

rwLock.readLock().lock();

Object result = null;

try{

System.out.println(Thread.currentThread().getName()+" 正在读取操作"+key);

//暂停一会

TimeUnit.MICROSECONDS.sleep( 300 );

result = map.get( key );

System.out.println(Thread.currentThread().getName()+" 取完了"+key);

}catch ( InterruptedException e ){

e.printStackTrace();

}finally{

//释放读锁

rwLock.readLock().unlock();

}

return result;

}

}

public class ReadWriteLockDemo {

public static void main( String[] args) throws InterruptedException {

MyCache myCache = new MyCache();

//创建线程放数据

for( int i = 1 ; i <= 5 ; i++ ){

final int num = i;

new Thread( () -> {

myCache.put( num + "" , num + "" );

} , String.valueOf( i ) ).start();

}

TimeUnit.MICROSECONDS.sleep( 300 );

//创建线程取数据

for( int i = 1 ; i <= 5 ; i++ ){

final int num = i ;

new Thread( () -> {

myCache.get( num + "" );

} , String.valueOf( i ) ).start();

}

}

}