监听应用是否返回后台

当点击Home键或其他原因造成应用进入后台，对于金融类App此时需要对其状态进行判断，进而做出相对于操作（一般吐司提示）。

public class MyApplication extends BaseApplication {
  @Override
  public void onCreate() {
        ......
       registerActivityLifecycleCallbacks(new ActivityLifecycleListener());
  }
}

给Application注册监听，当每个Activity都会触发它的回调。

public class ActivityLifecycleListener implements Application.ActivityLifecycleCallbacks {

    @Override
    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {

    }

    @Override
    public void onActivityStarted(Activity activity) {

    }

    @Override
    public void onActivityResumed(Activity activity) {

    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {
        if (isBackground(activity.getApplicationContext())) {
            //只对非正常退出做处理
            if (MyApplication.illegal) {
                Toast.makeText(activity.getApplicationContext(), "站住！别走~~", Toast.LENGTH_LONG).show();
            } else {
                MyApplication.illegal = true;
            }
        }
    }

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

    }

    @Override
    public void onActivityDestroyed(Activity activity) {

    }

    public static boolean isBackground(Context context) {
        ActivityManager activityManager = (ActivityManager) context
                .getSystemService(Context.ACTIVITY_SERVICE);
        List appProcesses = activityManager
                .getRunningAppProcesses();
        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.processName.equals(context.getPackageName())) {
                /*
                BACKGROUND=400 EMPTY=500 FOREGROUND=100
                GONE=1000 PERCEPTIBLE=130 SERVICE=300 ISIBLE=200
                 */
                if (appProcess.importance != ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    Log.i(context.getPackageName(), "处于后台"
                            + appProcess.processName);
                    return true;
                } else {
                    Log.i(context.getPackageName(), "处于前台"
                            + appProcess.processName);
                    return false;
                }
            }
        }
        return false;
    }
}