在您閱讀Android源碼的生涯中，您見過Android 框架層或者第三方框架哪些地方使用了單例模式？單例模式的實現(xiàn)是哪種方式？

android源碼里面一大堆單例模式，比如下面這個實現(xiàn)方法：靜態(tài)方法加同步鎖

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

EventBus，

    /** Convenience singleton for apps using a process-wide EventBus instance. */
    public static EventBus getDefault() {
        EventBus instance = defaultInstance;
        if (instance == null) {
            synchronized (EventBus.class) {
                instance = EventBus.defaultInstance;
                if (instance == null) {
                    instance = EventBus.defaultInstance = new EventBus();
                }
            }
        }
        return instance;
    }

太多了，比如很常用的LinkMovementMethod

    public static MovementMethod getInstance() {
        if (sInstance == null)
            sInstance = new LinkMovementMethod();

        return sInstance;
    }