在Android中使用 ”堆栈法“来完全退出应用程序

在Android开发中，有时候会遇到我们需要退出应用程序的时候，对于退出问题，众说纷云，有很多方法，至今本人没有发现较好的方法来解决这个问题：

1. 什么是”堆栈法“？

2. 什么时候适用”堆栈法“？

当app不支持横竖屏切换的时候，这时候用”堆栈法“来退出应用程序是最好的选择。如果你的app支持横竖屏切换，你需要保证你的Activity不被destroy()，否则就会直接退出，返回到桌面了。

3. 如何实现退出app的功能

step1. 把ScreenManager.java加到你的项目util工具包下，源代码如下：

/**

* This is a class used to exit from application. (poup all activities from stack)

*

*/

public class ScreenManager {

private static Stack<BaseActivity> activityStack;

private static ScreenManager instance;

private ScreenManager() {

}

public static ScreenManager getScreenManager() {

if (instance == null) {

instance = new ScreenManager();

}

if (activityStack == null) {

activityStack = new Stack<BaseActivity>();

}

return instance;

}

public void popActivity() {

BaseActivity activity = activityStack.lastElement();

if (activity != null) {

activity.finish();

activity = null;

}

}

public void popActivity(BaseActivity activity) {

if (activity != null) {

activity.finish();

activityStack.remove(activity);

activity = null;

}

}

public BaseActivity currentActivity() {

try {

BaseActivity activity = activityStack.lastElement();

return activity;

} catch (Exception e) {

return null;

}

}

public void pushActivity(BaseActivity activity) {

activityStack.add(activity);

}

public void popAllActivityExceptOne(Class<?> cls) {

while (true) {

BaseActivity activity = currentActivity();

if (activity == null) {

break;

}

if (activity.getClass().equals(cls)) {

break;

}

popActivity(activity);

}

}

public void popAllActivityAddMe(BaseActivity activity) {

while (true) {

BaseActivity a = currentActivity();

if (a == null) {

break;

}

if(!activity.equals(a))

popActivity(a);

else

activityStack.remove(activity);

}

pushActivity(activity);

}

public void popAllActivity() {

activityStack.removeAllElements();

activityStack.clear();

}

}

step2. 让所有yourActivity 继承 BaseActivity.java, BaseActivity.java的代码如下：

public class BaseActivity extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

ScreenManager.getScreenManager().popAllActivityAddMe(this);

}

｝

step3. 设置用户操作接口，用来退出。如 在登录页面当用户按back键时，这时候调用退出app功能。

在LoginActivity中添加：

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

// TODO Auto-generated method stub

if (keyCode == KeyEvent.KEYCODE_BACK) {

// skill LoginActivity or close the application

new AlertDialog.Builder(this).setTitle("").setIcon(R.drawable.icon).setMessage(

R.string.exit).setNegativeButton(

R.string.str_no, new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialog, int which) {

}

}).setPositiveButton(R.string.str_yes,

new DialogInterface.OnClickListener() {

public void onClick(final DialogInterface dialog,

int whichButton) {

dialog.dismiss();

ScreenManager.getScreenManager().popAllActivity();

android.os.Process.killProcess(android.os.Process.myPid());

finish();

System.exit(0);

}

}).show();

return false;

}

return super.onKeyDown(keyCode, event);

}

这样就可以完全退出app了，且此法通用于各个sdk version