如何处理Singleton以及序列化 [英] How to deal with Singleton along with Serialization

问题描述

考虑我有一个Singleton类定义如下。

Consider I have a Singleton class defined as follows.

public class MySingleton implements Serializable{
 private static MySingleton myInstance;

 private MySingleton(){

 }
  static{
    myInstance =new MySingleton();
 }
 public static MySingleton getInstance(){
    return MySingleton.myInstance;
 }
}

根据我的上述定义满足a的要求Singleton。添加的唯一附加行为是该类实现可序列化接口。

The above definition according to me satisfies the requirements of a Singleton.The only additional behaviour added is that the class implements serializable interface.

如果另一个类X获取单个实例并将其写入文件，稍后point反序列化它以获得另一个实例，我们将有两个实例违反Singleton原则。

If another class X get the instance of the single and writes it to a file and at a later point deserializes it to obtain another instance we would have two instances which is against the Singleton principle.

我如何避免这种情况，或者我在上面的定义本身是错误的。

How can I avoid this or am I wrong in above definition itself.

推荐答案

最好的方法是使用枚举单例模式：

The best way to do this is to use the enum singleton pattern:

public enum MySingleton {
  INSTANCE;
}

这保证了对象的单一性并为你提供了可串行化的功能。一种总是得到相同实例的方式。

This guarantees the singleton-ness of the object and provides serializability for you in such a way that you always get the same instance.

更一般地说，你可以提供一个 readResolve（）方法所以：

More generally, you can provide a readResolve() method like so:

protected Object readResolve() {
  return myInstance;
}

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