java - 如何从 InputMethodService 打开 ProgressDialog

Question

为什么我在 Eclipse 中收到以下代码的错误？

代码:

public class ServiceKeyboard extends InputMethodService implements KeyboardView.OnKeyboardActionListener
 {
   public  static ProgressDialog progressDialog;

...
   @Override public void onStartInput( EditorInfo attribute, boolean restarting)
    {
      super.onStartInput( attribute, restarting);
      progressDialog = new ProgressDialog( ServiceKeyboard.this);
      progressDialog.setMessage( getString( R.string.sSpinner));
// after this line crash
      progressDialog.show();
...
...
      if( progressDialog != null)  progressDialog.dismiss();
    }
 }

错误:

11-23 12:53:07.854: E/AndroidRuntime(23963): FATAL EXCEPTION: main
11-23 12:53:07.854: E/AndroidRuntime(23963): android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.view.ViewRootImpl.setView(ViewRootImpl.java:589)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:326)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:224)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:149)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.app.Dialog.show(Dialog.java:277)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at com.avanpost.mobile.ServiceKeyboard.onStartInput(ServiceKeyboard.java:354)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.inputmethodservice.InputMethodService.doStartInput(InputMethodService.java:1549)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.inputmethodservice.InputMethodService$InputMethodImpl.startInput(InputMethodService.java:388)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.inputmethodservice.IInputMethodWrapper.executeMessage(IInputMethodWrapper.java:158)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at com.android.internal.os.HandlerCaller$MyHandler.handleMessage(HandlerCaller.java:61)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.os.Looper.loop(Looper.java:137)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at android.app.ActivityThread.main(ActivityThread.java:4745)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at java.lang.reflect.Method.invokeNative(Native Method)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at java.lang.reflect.Method.invoke(Method.java:511)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-23 12:53:07.854: E/AndroidRuntime(23963):    at dalvik.system.NativeStart.main(Native Method)

当 softKeyboard (InputMethodService) 启动时，用 progressDialog 打开窗口的最佳解决方案是什么？

我尝试“new ProgressDialog(this);”、“new ProgressDialog(getApplicationContext());”而是“new ProgressDialog(ServiceKeyboard.this);”，但失败了。

Answer 1

我在创建没有关联 Activity 的 InputMethodService 时遇到了类似的问题。

这仅适用于 API 版本 12 及更高版本，但我设法通过传入输入 View 使用的窗口 token 来显示 ProgressDialog。只要发生这种情况，就可以使用应用程序上下文构造 ProgressDialog。

这需要 API 版本 12 的原因是 InputMethodService 必须实现 OnAttachStateChangeListener 以便在输入 View 附加到窗口时得到通知；尝试更早地执行该代码会导致空 token 。很可能在生命周期的后期有另一个地方放置 token 请求，但由于我的 IME 已经有这些 API 要求，所以我没有费心去寻找。

代码:

public class SampleKeyboardService extends InputMethodService
                                   implements OnAttachStateChangeListener {
  private View mInputView;
  private ProgressDialog mProgress;

  @Override
  public View onCreateInputView() {
      super.onCreateInputView();
      LayoutInflater inflater =
          (LayoutInflater) getSystemService(Service.LAYOUT_INFLATER_SERVICE);
      mInputView = inflater.inflate(R.layout.input, null);
      mInputView.addOnAttachStateChangeListener(this);
      return mInputView;
  }

  /* ... */

  @Override
  public void onViewAttachedToWindow(View view) {
      Window progressWindow = mProgress.getWindow(); // mProgress created earlier
      WindowManager.LayoutParams layoutParams = progressWindow.getAttributes();
      layoutParams.token = view.getWindowToken();
      layoutParams.type = 
          WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
      progressWindow.setAttributes(layoutParams);
  }
}

另见 https://stackoverflow.com/a/13962770/793212