我试图重写的返回键preSS的功能。当用户presses一次，我希望它回来了previous屏幕。然而，当返回键是长期pressed（对，比方说，2秒以上），我想退出应用程序。

I'm trying to override the functionality of the back key press. When the user presses it once, I want it to come back to the previous screen. However, when the back key is long-pressed (for, let's say, two seconds or more), I want to exit the application.

到现在为止，我已经重写我的活动这两种方法：

By now, I have overriden these two methods in my activity:

@Override
public boolean onKeyDown( int keyCode, KeyEvent event){
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        //manage short keypress
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

@Override
public boolean onKeyLongPress( int keyCode, KeyEvent event){
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        //manage long keypress (different code than short one)
        return true;
    }
    return super.onKeyLongPress(keyCode, event);
}

但 onKeyLong preSS 回调不会被调用，因为事件总是收到的onkeydown 方法。

But the onKeyLongPress callback is never called, because the event is always received by the onKeyDown method.

有什么办法有两种方法工作的？抑或是做所有的的onkeydown 和使用的重复/毫秒的数量来检测呢？

Is there any way of having both methods working? Or has it to be done all in the onKeyDown and use the number of repetitions/milliseconds to detect it?

推荐答案

之所以 onKeyLong preSS 不会被调用，是您在的onkeydown 瞒着，这可能是一个漫长的preSS框架 - 造成的KeyEvent通过不同的事件处理程序，以阻止其流动

The reason why onKeyLongPress is never called, is that you return true in onKeyDown without telling the framework that this might be a long press - causing the KeyEvent to stop its flow through the different event handlers.

您需要做的是这样的：

实现如下，它会工作：

  @Override
  public boolean onKeyDown( int keyCode, KeyEvent event ) {
    if( keyCode == KeyEvent.KEYCODE_BACK ) {
      event.startTracking();
      return true; 
    }
    return super.onKeyDown( keyCode, event );
  }

  @Override
  public boolean onKeyUp( int keyCode, KeyEvent event ) {
    if( keyCode == KeyEvent.KEYCODE_BACK ) {
      //Handle what you want on short press.      
      return true; 
    }

    return super.onKeyUp( keyCode, event );
  }

  @Override
  public boolean onKeyLongPress( int keyCode, KeyEvent event ) {
    if( keyCode == KeyEvent.KEYCODE_BACK ) {
      //Handle what you want in long press.
      return true;
    }
    return super.onKeyLongPress( keyCode, event );
  }