Android实战技巧：Dialog

转：http://blog.csdn.net/hitlion2008/article/details/7567549#t0

Dialog是任何系统都必须有的一个控件，作为辅助窗口，用于显示一些消息，或请求用户采取一引起操作等。

在Android中也不例外，基本使用可能参看文档。

使用时的注意事项

1. BACK键能取消掉对话框(dismiss)，但是却不会触发其onOkey和onCancel回调接口，所以如果你的对话框会改某些状态，一定要注意还有第三种方式取消对话框。

2. 尽量少用模态对话框(Model dialog)，如果Dialog.setCancellable(false)，就变成了一个模态对话框，除了程序内部把其Dismiss，否则按什么键都无法将其取消。这是极差的用户体验，对话框本身就是一种干扰，再无法取消会把用户搞疯的。所以除非特别有必要，也即当执行某个操作时不希望被打破，才可以使用模态对话框。

3. 尽量少用对话框，它对用户是一种干扰，除非需要用户做操作，或者做出选择。通常的一般性的通知用Toast或者Notification就足够了。

4. 不要使用对话框风格的Activity，也即把Activity变成一个对话框。因为这样是自已定义的布局，与系统Dialog的风格可能会不一致。最严重的是当系统风格发生变化，Dialog的子类会变化，但Activity式的对话框就不会变化。可以在ICS中找一找Activity对话框，你会发现其OK是在左边，而ICS中系统Dialog的OK都是在右边的。

5. 尽量保证Dialog对象活在Activity的生命周期之内，也即至多是在onCreate()和onDestroy()之间。

6. 要想到和测试到Activity在其Dialog.dismiss()之前死掉的情况。因为Activity必须依附于某个正在显示的Activity实例，当显示和取消的时候其Activity实例必须存在，否则就会有"IllegalArgumentException: View not attached to window manager"。

05-15 02:45:26.320: E/AndroidRuntime(1161): java.lang.IllegalArgumentException: View not attached to window manager05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.view.WindowManagerImpl.findViewLocked(WindowManagerImpl.java:355)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.view.WindowManagerImpl.removeView(WindowManagerImpl.java:200)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.view.Window$LocalWindowManager.removeView(Window.java:432)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog.dismissDialog(Dialog.java:278)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog.access$000(Dialog.java:71)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog$1.run(Dialog.java:111)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.app.Dialog.dismiss(Dialog.java:268)05-15 02:45:26.320: E/AndroidRuntime(1161):     at com.hilton.effectiveandroid.app.DialogDemo$1.handleMessage(DialogDemo.java:26)05-15 02:45:26.320: E/AndroidRuntime(1161):     at android.os.Handler.dispatchMessage(Handler.java:99)

7. Dialog.show()必须在主线程里调用，但Dialog.dismiss()却可以在任何线程中调用。

三种使用方式比较

1. 直接创建一个局部的Dialog对象

优点是变量是局部的容易理解和维护。缺点是Dialog对象难以控制，容易引发RuntimeException。

2. 把Dialog对象变成Activity的域

优点是Dialog对象可以重复利用，且Activity可以控制以保证Dialog不会在Activity生命周期外显示。是推荐的使用方式。

3. 用Activity的方法onCreateDialog(), showDialog()和dismissDialog()

优点是Frameworks会帮忙照看Dialog，在大多数情况下这是推荐的做法。但是对于Activity提前死掉的情况，此方法必有RuntimeException，且无法回避。

实例

public class DialogDemo extends Activity {    private static final int DISMISS_DIALOG = 1;        private ProgressDialog mBetterDialog;    private Handler mMainHandler = new Handler() {@Overridepublic void handleMessage(Message msg) {    switch (msg.what) {    case DISMISS_DIALOG:Dialog dialog = (Dialog) msg.obj;dialog.dismiss();break;    default:break;    }}    };    @Override    protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.dialog_demo);final Button sucking = (Button) findViewById(R.id.sucking);sucking.setOnClickListener(new View.OnClickListener() {    public void onClick(View v) {final Activity activity = DialogDemo.this;final ProgressDialog dialog = new ProgressDialog(activity);dialog.setTitle("Worst dialogging");dialog.setMessage("This is the worst dialogging scheme, NEVER use it. This dialog is easy to " +"run out of its attached activity, yielding WindowManager#BadTokenException if the activity is gone when dismissing");dialog.setIndeterminate(true);dialog.setCancelable(true);// You MUST do the show in main thread anywaydialog.show();new Thread(new Runnable() {    public void run() {SystemClock.sleep(10000);/* * IllegalArgumentException: View not attached to window manager * If the activity showing the dialog was killed before dismiss() out of rotation or locale changed, * the dialog will gone with activity, but when dismiss() yields "IllegalArgumentException: View not attached to  * window manager". * Checking isShowing() won't help. * Checking activity.isFinishing() won't help, either. * Dismiss it in main thread also won't give any help. */// THIS WON't WORK//if (dialog.isShowing()) {//    dialog.dismiss();//}//if (!activity.isFinishing()) {//    dialog.dismiss();//}Message msg = Message.obtain();msg.what = DISMISS_DIALOG;msg.obj = dialog;mMainHandler.sendMessage(msg);    }}).start();    }});final Button better = (Button) findViewById(R.id.better);better.setOnClickListener(new View.OnClickListener() {    public void onClick(View v) {mBetterDialog = new ProgressDialog(DialogDemo.this);mBetterDialog.setTitle("Better dialogging");mBetterDialog.setMessage("This dialogging can be used. The dialog object is a field of its activity, so activity can" +" control it to make sure dialog only lives within activity lifecircle");mBetterDialog.setIndeterminate(true);mBetterDialog.setCancelable(true);// You MUST do the show in main thread anywaymBetterDialog.show();new Thread(new Runnable() {    public void run() {SystemClock.sleep(10000);/* * This is much better, mBetterDialog is a field of its activity, so activity can take care of it in order * to make sure dialog only live within activity's life circle, to avoid any unexpected exceptions. */// THIS really works    if (mBetterDialog != null && mBetterDialog.isShowing()) {        mBetterDialog.dismiss();    }    }}).start();    }});final Button optional = (Button) findViewById(R.id.optional);optional.setOnClickListener(new View.OnClickListener() {    @SuppressWarnings("deprecation")    public void onClick(View v) {showDialog(0);new Thread(new Runnable() {    public void run() {SystemClock.sleep(10000);/* * This way works best for most of time, except if activity died before dismissing, exception must be * thrown: "IllegalArgumentException: View not attached to window manager". * Although activity takes care of its belonging dialog, there is no way to operate it manually any more. * First you do not have reference to dialog object and second, any manual operation only interferences * and breaks state maintained by frameworks. */dismissDialog(0);    }}).start();    }});    }    @Override    protected Dialog onCreateDialog(int id) {ProgressDialog d = new ProgressDialog(this);d.setTitle("Optional dialogging");d.setMessage("This dialogging scheme works best for most times, the dialogs are all taken care of by activitys and frameworks" +". Except for activity being killed during dialog showing");d.setIndeterminate(true);d.setCancelable(true);return d;    }    @Override    protected void onDestroy() {super.onDestroy();// Activity is dying, all its belonging dialogs should be dismissed, of course.if (mBetterDialog != null && mBetterDialog.isShowing()) {    mBetterDialog.dismiss();    mBetterDialog = null;}// For dialogs showed via showDialog(int), no way to stop it in onDestroy()//dismissDialog(0); // cause "IllegalArgumentException: no dialog with id 0 was ever shown via Activity#showDialog"    // This is because Activity has to manage its dialog during onPause() and onResume() to restore                  // dialogs' state. So if you manually dismiss it in onDestroy(), it will cause JE.//removeDialog(0);// cause "IllegalArgumentException: no dialog with id 0 was ever shown via Activity#showDialog", when// dismissing in thread.               // This is because Activity has to manage its dialog during onPause() and onResume() to restore                     // dialogs' state. So if you manually dismiss it in onDestroy(), it will cause JE.    }}

使用时的注意事项

三种使用方式比较

实例

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