Android 阻隔返回键

 //阻隔 返回键
 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
     if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
         exitBy2Click();// 双击退出
         return true;
     }
     return super.onKeyDown(keyCode, event);  //true -- 事件传递机制：false不拦截、true拦截
 }