android 处理Back键按下事件

package com.example.keyevent;

import android.os.Bundle;
import android.view.KeyEvent;
import android.app.Activity;
/**
* Demo描述:
* 处理Back键按下事件
*
* 注意事项:
* 以下两种方法勿一起使用
*/
public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
/**
* 监听Back键按下事件,方法1:
* super.onBackPressed()会自动调用finish()方法执行 onDestroy(),关闭
* 当前Activity.
* 若要屏蔽Back键盘,注释该行代码即可
*/
@Override
public void onBackPressed() {
super.onBackPressed();
System.out.println("按下了back键   onBackPressed()");
}

/**
* 监听Back键按下事件,方法2:
* 在此处返回false,所以会继续传播该事件. 继续执行super.onKeyDown(keyCode, event);
*/
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
System.out.println("按下了back键   onKeyDown()");
return false;
}else {
return super.onKeyDown(keyCode, event);
}
}

@Override
protected void onDestroy() {
super.onDestroy();
System.out.println("执行 onDestroy()");
}
}