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()");
    }
}