Java中的单例模式的总结

最新推荐文章于 2025-11-18 23:02:08 发布

原创最新推荐文章于 2025-11-18 23:02:08 发布 · 315 阅读

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本文介绍了四种不同的单例模式实现方式：非延迟加载、简单同步延迟加载、双重检查锁定的延迟加载及利用静态内部类实现的延迟加载。每种实现都有其特点和适用场景。

<strong>//第一种非延迟加载的单利模式</strong>

<strong>public class  SingleInstance{
    private SingleInstance(){};
    private static final SingleInstance mSingleInstance=new SingleInstance();
    public static SingleInstance getInstance()
    {
        return mSingleInstance;
    }
}</strong>


<strong>//第二种 简单的同步延迟加载,效率相对较低
public class  SingleInstance{
    private SingleInstance(){};
    private static  SingleInstance mSingleInstance=null;
    public  static  synchronized  SingleInstance getInstance()
    {
        if (mSingleInstance==null)

            mSingleInstance=new SingleInstance();
        return  mSingleInstance;
    }
}</strong>


<strong>//第三种 双重延迟的加载
public class  SingleInstance{
    private SingleInstance(){};
    private static volatile SingleInstance mSingleInstance=null;
    public  static   SingleInstance getInstance()
    {
        if (mSingleInstance==null)
        {
            synchronized (SingleInstance.class)
            {
                if (mSingleInstance==null)
                {
                    mSingleInstance=new SingleInstance();
                }
            }
        }

        return  mSingleInstance;
    }
}</strong>

<strong>
//类加载器的延迟加载的单例模式
public class SingleInstance{
    private static class HolderClass{
        static final SingleInstance mSingleInstance=new SingleInstance();
    }

    public static  SingleInstance getInstance()
    {
        return HolderClass.mSingleInstance;
    }
}
</strong>