package cn.itcast.day3.thread;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
//设计缓冲系统
public class CacheDemo {
private Map<String, Object> cache = new HashMap<String, Object>();
public static void main(String[] args) {
// TODO Auto-generated method stub
}
private ReadWriteLock rwl = new ReentrantReadWriteLock();
public Object getData(String key){
rwl.readLock().lock();
Object value = null;
try{
value = cache.get(key);
if(value == null){
//读写锁的作用
rwl.readLock().unlock();
rwl.writeLock().lock();
try{
if(value==null){
value = "aaaa";//实际失去queryDB();
}
}finally{
rwl.writeLock().unlock();
}
rwl.readLock().lock(); //系统性能提高
}
}finally{
rwl.readLock().unlock();
}
return value;
}
}
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
//设计缓冲系统
public class CacheDemo {
private Map<String, Object> cache = new HashMap<String, Object>();
public static void main(String[] args) {
// TODO Auto-generated method stub
}
private ReadWriteLock rwl = new ReentrantReadWriteLock();
public Object getData(String key){
rwl.readLock().lock();
Object value = null;
try{
value = cache.get(key);
if(value == null){
//读写锁的作用
rwl.readLock().unlock();
rwl.writeLock().lock();
try{
if(value==null){
value = "aaaa";//实际失去queryDB();
}
}finally{
rwl.writeLock().unlock();
}
rwl.readLock().lock(); //系统性能提高
}
}finally{
rwl.readLock().unlock();
}
return value;
}
}
本文介绍了一个使用读写锁实现的缓存系统设计方案。该方案通过ReentrantReadWriteLock确保并发访问时的数据一致性,同时利用HashMap存储缓存数据。文章详细解释了读写锁的工作原理及其实现方式。
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