android - 如何从输入法服务启动 PopupWindow 或 Dialog？

Question

当我尝试从 InputMethodService 中弹出 PopupWindow(或 Dialog)时出现同样的异常:

FATAL EXCEPTION: main
android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?
     at android.view.ViewRoot.setView(ViewRoot.java:505)
     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
     at android.widget.PopupWindow.invokePopup(PopupWindow.java:828)
     at android.widget.PopupWindow.showAtLocation(PopupWindow.java:688)
     at mypackage.MyInputMethodService.onClick(MyInputMethodService.java:123)
     ...

如果我尝试弹出一个对话框，我会在 ViewRoot.java 的同一行中得到完全相同的异常。这是我的代码(已删节):

public class MyInputMethodService
    extends InputMethodService 
    implements View.OnClickListener {

    public void onClick(View v) {
        // This is the handler for View.OnClickListener
        LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        PopupWindow pw = new PopupWindow(inflater.inflate(R.layout.popup_example, null, false), 100, 100, true);
        pw.showAtLocation(mInputView, Gravity.CENTER, 0, 0);
        // mInputView was previously created and returned by onCreateInputView()
    }
} // end of MyInputMethodService

和

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dip"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:text="Test Pop-Up"
    />
</LinearLayout>

我已经尝试了上述代码的许多变体，但 PopupWindows 和 Dialogs 总是得到相同的异常。出于某种原因， toast 警报有效。是否有一种特殊的技术可以从 Service(特别是 InputMethodService)而不是 Activity 启动 PopupWindow 或 Dialog？

提前致谢

巴里

Answer 1

实际上我设法做到了，试试这个:

 AlertDialog.Builder builder = new AlertDialog.Builder(this);
                 builder.setTitle("Make your selection");
                 builder.setItems(items, new DialogInterface.OnClickListener()
                 {
                    public void onClick(DialogInterface dialog, int item)
                    {
                       // Do something with the selection
                    }
                 });
                 AlertDialog alert = builder.create();
                 Window window = alert.getWindow();
                 WindowManager.LayoutParams lp = window.getAttributes();
                 lp.token = mInputView.getWindowToken();
                 lp.type = WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
                 window.setAttributes(lp);
                 window.addFlags(WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
                 alert.show();