应用进入后台的判断

当所有Activity都执行过stop可以理解为进入后台

在Application类里执行注册:
registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {
            @Override
            public void onActivityCreated(Activity activity, Bundle bundle) {
            }

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

            @Override
            public void onActivityResumed(Activity activity) {
            }

            @Override
            public void onActivityPaused(Activity activity) {
                // 不在pause上做，因为可能只是被简单的第三方遮住
            }

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

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

            }

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