屏蔽Home键

Android 如何屏蔽Home键（长按短按都不起作用）。
package com.test.qiao;  
  
import android.app.Activity;  
import android.os.Bundle;  
import android.view.KeyEvent;  
import android.view.WindowManager;  
  
public class ZZZActivity extends Activity {  
      
    private boolean flag = true;//true位屏蔽，false位不屏蔽   
      
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
    }  
    @Override  
    public void onAttachedToWindow() {  
        if(flag) {  
            this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);  
        }  
        super.onAttachedToWindow();  
    }  
  
    @Override  
    public boolean onKeyDown(int keyCode, KeyEvent event) {  
        if(keyCode == KeyEvent.KEYCODE_HOME){  
            return true;  
        }