实现缓存 java实现

主要用了java的读写锁，读的时候加读锁，要写入数据的时候加写锁，不难的

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

public class CacheDemo {
private static Map<String, Object> map = new HashMap<String, Object>();
private static ReadWriteLock rwl = new ReentrantReadWriteLock();
public static void main(String[] args) {

}
public static Object get(String id) {
Object value = null;
rwl.readLock().lock();
try {
value = map.get(id);
if (value == null) {
rwl.readLock().unlock();
rwl.writeLock().lock();
try {
if (value == null) {
value = "aaa";
}//这边可以根据自己的需要改改,我随便写的
} finally {
rwl.writeLock().unlock();
}
rwl.readLock().lock();
}
} finally {
rwl.readLock().unlock();
}
return value;
}

public static void set(String id, Object test) {
rwl.writeLock().lock();
try {
if(map.containsKey(id)) {
map.remove(id);
map.put(id, test);
}
} finally {
rwl.writeLock().unlock();
}
}
}