java模拟数据库缓存
标签：pre 压力 code map try private 写锁 模拟 nal
java模拟数据库缓存
public class CatheDemo {
private Map<String, Object> map = new HashMap<String, Object>();
private ReadWriteLock rwl = new ReentrantReadWriteLock(); //定义读写锁
public Object getData(String key){
rwl.readLock().lock();
Object value = null;
try {
value = map.get(key);
if (value == null) {
rwl.readLock().unlock();
rwl.writeLock().lock();
try {
if(value == null)
value = "dqwdwqd"; //从数据库中查找数据
} catch (Exception e) {
e.printStackTrace();
}finally{
rwl.writeLock().unlock();
rwl.readLock().lock();
}
}
} catch (Exception e) {
e.printStackTrace();
}finally{
rwl.readLock().unlock();
}
return value;
}
}