如何将抽象工厂与单件模式相结合？ [英] How do you combine abstract factory with singleton pattern?

问题描述

我在java编码，对这些模式很新。谁能给我一个工厂抽象的例子也使用单例？

I am coding in java and am new with these patterns. Can anyone give me an example of a factory abstract also using singleton?

推荐答案

这是一个实现的类的例子单身模式。此实现也线程安全。它使用双重检查锁定，以便仅在需要时进行同步。

Here's an example of a class implementing the singleton pattern. This implementation is also thread safe. It uses double-checked locking in order to only synchronize when needed.

public class Singleton {
    private volatile static Singleton instance; // Note volatile keyword.

    private Singleton() {}

    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (Singleton.class) {
                if (instance == null) {
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }
}

您可以添加任何（工厂）方法作为成员类 Singleton 。当您获得唯一实例时，这些方法将可用。

You can add any (factory) methods as members of the class Singleton. These methods will become available when you get the unique instance.

public class Singleton {
    /* ... */
    /* Singleton implementation */
    /* ... */

    public MyObject createMyObject() { // Factory method.
        return new MyObject();
    }

    // ...
}

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