preferencefragment如何添加底部button？？？？

package com.example.Androidpreferencefragment;

import android.app.Activity;
import android.os.Bundle;

public class SetPreferenceActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);

getFragmentManager().beginTransaction().replace(android.R.id.content,
new PrefsFragment()).commit();
}

}

public class PrefsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener{

@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);

// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences);
}
｝

自定义一个Preference就可以了。