DialogFragment 监听按键事件的方法（onkeydown）

this.getDialog().setOnKeyListener(new OnKeyListener()
        {
           public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event){
           if (keyCode == KeyEvent.KEYCODE_SEARCH)
             return true; // pretend we've processed it
           else
             return false; // pass on to be processed as normal
         }
       });