继续学习Android,我读了以下内容:

Question: Does the user have a choice to kill the application unless we put a menu option in to kill it? If no such option exists, how does the user terminate the application? Answer: (Romain Guy): The user doesn't, the system handles this automatically. That's what the activity lifecycle (especially onPause/onStop/onDestroy) is for. No matter what you do, do not put a "quit" or "exit" application button. It is useless with Android's application model. This is also contrary to how core applications work.

呵呵,我在Android世界里每走一步都会遇到一些问题=(

显然,你不能在Android中退出应用程序(但Android系统可以随时完全销毁你的应用程序)。这是怎么回事?我开始认为这是不可能写一个应用程序的功能作为“正常的应用程序”-用户可以退出应用程序时,他/她决定这么做。这不应该依靠操作系统来完成。

我正在尝试创建的应用程序不是Android市场的应用程序。它不是一个被大众“广泛使用”的应用程序,它是一个将在非常狭窄的商业领域使用的商业应用程序。

我其实很期待为Android平台开发,因为它解决了Windows Mobile和。net中存在的许多问题。然而,上周对我来说有点令人失望……我希望我不必放弃Android,但它现在看起来不太好=(

有办法让我真的退出应用程序吗?


当前回答

目前,我在我的应用程序中实现了以下内容。可能这些有助于从应用程序中移动出来,无论你想要的是什么。我从操作栏菜单中调用这个函数。

public static void exitApplication(Context context) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        exitApplicationHC(context);
    }
    else {
        exitApplicationPreHC(context);
    }
}

private static void exitApplicationPreHC(Context context) {
    Intent i = new Intent(context, LoginActivity.class);
    i.putExtra(EXTRA_EXIT, true);
    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(i);
    if (context instanceof Activity) {
        ((Activity) context).finish();
    }
}

@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private static void exitApplicationHC(Context context) {
    Intent i = new Intent(context, LoginActivity.class);
    i.putExtra(EXTRA_EXIT, true);
    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
    context.startActivity(i);
}

其他回答

博客文章“何时在Android应用程序中包含退出按钮”(提示:永远不要)解释得比我好得多。我希望每个Android开发者都读过这本书。

摘录:

In my experience what [the users] really want is: An unambiguous way to guarantee that an app will stop consuming resources (battery, CPU cycles, data transfer, etc.). Many users perceive that an exit button implements this requirement and ask for it to be added. Developers, looking to please their users, obligingly add one. Shortly thereafter they both fail. In most cases the exit button simply calls Activity.finish(). This is exactly equivalent to hitting the back button. Exactly. Services keep running and polling keeps happening. Users may think they've killed the app but they haven't, and soon they'll be even more annoyed. Exit behavior is now ambiguous. Should your exit button just close the Activity, or should it also stop all associated Services, Receivers, and Alarms? What should Back do? What happens if they hit Home instead? What happens if your app has a widget? Should the exit button stop that from updating too? The solution is to make the back button behave as you'd expect the exit button to. Better yet, simply stop consuming resources whenever the app isn't visible.

继续阅读完整的文章。

如果你无法理解如何让你的数据/连接(因此你的“应用程序”)持久,那么你将无法用Android做你“需要”做的事情。

那些下载了这些可爱的小应用程序杀手的人通常会发现,它们对电池寿命或内存使用没有帮助,反而阻碍了操作系统有效管理内存的工作……

http://android-developers.blogspot.com/2010/04/multitasking-android-way.html

回答:(罗曼盖伊):用户不需要,系统会处理这个问题 自动。这就是活动生命周期(特别是 onPause/onStop/onDestroy)用于。无论你做什么,都不要放不下 “退出”或“退出”应用程序按钮。这在安卓系统中毫无用处 应用程序模型。这也与核心应用程序的方式相反 工作。

1: Totally exiting an application may be generally unmandatory, but it is not useless. What if windows had no exit option? System would be doggy slow as memory was full and the OS had to guess at which programs you were done with. I don't care what Romain Guy or even Larry Page and Sergey Brin say - these are unquestionable facts: Systems run slower when they have to kill tasks to get their memory before a new app can be launched. You just can't tell me that it doesn't take time to kill an app! Even the light from distant stars take time... There is some use in allowing the user to fully close apps.

2:与核心应用程序的工作方式相反?这是什么意思?当我现在运行一个应用程序时,它不再做任何工作……它只是在需要内存时等待被操作系统杀死。

总而言之,最小化和退出之间有明显的区别,两者都不适合对方。每个螺丝上都留个螺丝刀吗?还是每扇门都有钥匙?我们是不是把所有的电器都开着,直到断路器爆炸,我们需要打开另一个电器?我们是不是把洗碗机里装满了盘子,每次只拿出足够的空间来放一些新的脏盘子?我们把所有的车都停在车道上,直到——哦,算了。

如果用户想要最小化应用程序,那么最好的方法就是最小化它。如果用户想要退出应用程序,那么无论如何最好是退出。

这会让人皱眉吗?这是Android的观点——他们不赞成。许多独立的Android新手开发者对此表示不满。

但当它落到实处时,有好的编码和坏的编码。有好的程序流模型也有坏的程序流模型。

当用户知道他们已经用完了程序时,把程序留在内存中并不是好的程序流程。它完全没有任何用处,而且在启动新应用程序或运行应用程序分配更多内存时,它会减慢运行速度。

这有点像你的汽车:有时你让它一直开着,比如在红绿灯前停车,或者在快餐店经过时停车,或者在自动取款机前停车。但在其他情况下,你确实想把它关掉——比如当你去工作的时候,或者在杂货店,甚至在家里。

同样地,如果你正在玩游戏,这时手机响了。暂停游戏并继续运行。但如果用户已经玩了一段时间,那就让他们退出游戏吧。

The exit button on some applications should be more out in front than others. Games, for example, or programs where the user is likely to want to fully exit, should have an obvious exit. Other programs, like, perhaps, email programs, where exiting is an unlikely desire (so that it can keep checking for email) -- these programs should not waste prime control input screen space with an exit option, but for good program flow, it should have an exit option. What if someone decides they don't want their mail program trying to check email when they are in poor coverage area, or maybe in a Skype call or whatever? Let them exit the email program if they want!

暂停和退出是两项至关重要的任务,两者都不能实现对方的作用。

如果你指定API >= 16, Activity#finishAffinity()可以满足你的需求。

如果你有10个,20个…有多个活动正在运行,你想要完成所有活动并退出系统。

在应用程序类或常量类中创建静态数组。

常量

public class Constants {

public static ArrayList<Activity> activities = new ArrayList<Activity>();

}

在此数组中添加当前活动引用

activity = MainActivity.this; Constants.activities.add(活动);

public class MainActivity extends Activity {

    private ImageView imageButton;
    private Activity activity;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        activity = MainActivity.this;
        Constants.activities.add(activity);

        imageButton = (ImageView) findViewById(R.id.camera);
        imageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                // existing app.
                if (Constants.activities != null) {
                    for (int i = 0; i < Constants.activities.size(); i++) {
                        Activity s = Constants.activities.get(i);
                        s.finish();
                    }
                }
                //super.finish();
                finish();
                android.os.Process.killProcess(android.os.Process.myPid());
                System.exit(1);
            }
        });
    }
}