Singleton 的较好的实现方法

时间 2019-11-09

标签 singleton 较好实现方法繁體版

原文原文链接

1. 静态持有者单例模式（static holder singleton pattern） html

public static class Singleton {
    private static class InstanceHolder {
        public static Singleton instance = new Singleton();
    }

    private Singleton(){}

    public static Singleton getInstance() { 
        return InstanceHolder.instance;
    }
}

有三个好处：java

第一，静态工厂；第二，延迟初始化；第三，线程安全。安全

2. 双重检查锁（singleton with double checked locking）线程

public class Singleton {
    private Singleton(){
    }

    private static Singleton instance;
    
    public static Singleton getInstance() {
        if (instance == null) {                // Single checked
            synchronized (Singleton.class) {
                if (instance == null) {        // Double checked
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }
}

参考文献code

3. 使用枚举（Making singletons with Enum in Java）htm

public enum EnumSingleton {
    INSTANCE;
 
    // other methods...
}

Why Enum Singleton are better in Javablog