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为屏蔽，false、为不屏蔽    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }@Overridepublic void onAttachedToWindow() {if(flag) {this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);}super.onAttachedToWindow();}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if(keyCode == KeyEvent.KEYCODE_HOME){return true;}return super.onKeyDown(keyCode, event);}}