Android返回键

不说啥啦，，直接上代码

		boolean isExit;
		@Override
		public boolean onKeyDown(int keyCode, KeyEvent event) {
			if (keyCode == KeyEvent.KEYCODE_BACK) {
				if (!isExit) {
					isExit = true;
					Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();
					mHandler.sendEmptyMessageDelayed(0, 2000);
				} else {
					Intent intent = new Intent(Intent.ACTION_MAIN);
					intent.addCategory(Intent.CATEGORY_HOME);
					startActivity(intent);
					System.exit(0);
				}
				return false;
			} else {
				return super.onKeyDown(keyCode, event);
			}
		}
		Handler mHandler = new Handler() {

			@Override
			public void handleMessage(Message msg) {
				// TODO Auto-generated method stub
				super.handleMessage(msg);
				isExit = false;
			}

		}