android之对话框存在时，有时候无法捕获back键

android之对话框存在时，有时无法捕获back键
见博客文章

http://blog.csdn.net/wangpp2009/article/details/7106906

1）给对话框加监听，代码如下：

dialog.setOnKeyListener(new OnKeyListener()            {                @Override                public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event)                {                    if(keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount()==0)                    {                        dialog.dismiss();                    }                    return false;                }            });

(2)捕捉back键，重写dispatchKeyEvent()方法，注意不是onKeyDown()方法。代码如下：

public boolean dispatchKeyEvent(KeyEvent event)    {                switch(event.getKeyCode())        {        case KeyEvent.KEYCODE_BACK:                       clearData();                        break;        default:            break;        }        return super.dispatchKeyEvent(event);    }

通过对话框主动监听back键，这样才能避免对话框存在时无法捕获back键。