重写dispatchKeyEvent方法 按返回键back 执行两次的解决方法

1. 转自：http://blog.csdn.net/qiaoning13256/article/details/7612059
2. @Override??????public?boolean?dispatchKeyEvent(KeyEvent?event)?{??
3. ????????if(event.getKeyCode()?==?KeyEvent.KEYCODE_BACK?&&?event.getAction()?!=?KeyEvent.ACTION_UP)?{//不响应按键抬起时的动作???????????????//TODO?代码????
4. ????????????System.out.println("Back?pressed.?event.getKeyCode()?=>?"?+?event.getKeyCode()?+?",?event.getKeyCode()?=>?"?+?event.getAction());??????????????return?true;//注意这儿返回值为true时该事件将不会继续往下传递，false时反之。根据程序的需要调整??
5. ????????}??????????return?super.dispatchKeyEvent(event);??
6. ????}??

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