【Java基础】线程笔记——线程安全的单例模式的写法

线程安全，高并发性能不高

public class SingletonOne {

private static SingletonOne instance;

private static ReentrantLock lock = new ReentrantLock();

private SingletonOne(){

}

public static SingletonOne getInstance(){
if(instance == null){
lock.lock();
if(instance == null){
instance = new SingletonOne();
}
lock.unlock();
}
return instance;
}

}

线程安全、性能高

public class SingletonTwo {

private static SingletonTwo instance;

private static byte[] lock = new byte[0];

private SingletonTwo(){

}

public static SingletonTwo getInstance(){
if(instance == null){
synchronized (lock) {
if(instance == null){
instance = new SingletonTwo();
}
}
}
return instance;
}

}