Android中监听应用进入后台

最近看到好几个银行类app，应用切出去之后会提示“XXX进入后台运行”

API 14之后，Application可以注册ActivityLifecycleCallbacks这个接口

application.registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {
            @Override
            public void onActivityCreated(Activity activity, Bundle bundle) {
            }

            @Override
            public void onActivityStarted(Activity activity) {
                //说明从后台回到了前台
                mFinalCount++;
            }

            @Override
            public void onActivityResumed(Activity activity) {
            }

            @Override
            public void onActivityPaused(Activity activity) {

            }

            @Override
            public void onActivityStopped(Activity activity) {
                mFinalCount--;
                //说明从前台回到了后台
                if (mFinalCount == 0 ) {
                    ToastTools.showShort(application.getApplicationContext(), "进入后台运行");
                }
            }

            @Override
            public void onActivitySaveInstanceState(Activity activity, Bundle bundle) {

            }

            @Override
            public void onActivityDestroyed(Activity activity) {
            }
        });