Java 序列化。不同的引用

Question

这个问题已经有答案了:

How to deal with Singleton along with Serialization (9 个回答)

已关闭 7 年前。

public static class Singleton implements Serializable {
    private static Singleton ourInstance;

    public static Singleton getInstance() 
    {
        if (ourInstance == null) 
        {
            ourInstance = new Singleton();
        }
        return ourInstance;
    }     
    private Singleton() {
    }
}

<小时/>

     Singleton instance = Singleton.getInstance();
     objectOutputStr.writeObject(instance);
      Singleton singleton1 = (Singleton) objInputStr.readObject();
      Singleton singleton2 = (Singleton) objInputStr.readObject();
      System.out.println(singleton1);//A
      System.out.println(singleton2);//B

为什么 singleton1 和 singleton2 的输出不同(标记为 A 和 B 的行)。是否可以使两个引用相同。

Answer 1

尝试使用我添加的行重新运行您的应用程序，如下所示:

  Singleton instance = Singleton.getInstance();
  objectOutputStr.writeObject(instance);
  Singleton singleton1 = (Singleton) objInputStr.readObject();
  objectOutputStr.writeObject(instance); //Added an additional write to stream
  Singleton singleton2 = (Singleton) objInputStr.readObject();
  System.out.println(singleton1);//A
  System.out.println(singleton2);//B