PreferenceGroup中RingtonePreference的用法

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
    
<PreferenceCategory 
    android:title="铃声设置">
    <RingtonePreference 
        android:title="提示音"
        android:summary="默认铃声"
        android:key="key_ringtone_preference"
        android:ringtoneType="ringtone"/>
</PreferenceCategory>
</PreferenceScreen>

public class MainActivity extends Activity implements OnClickListener {
 
	private Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button) findViewById(R.id.button_settings);
        button.setOnClickListener(this);
    }
	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		getFragmentManager().beginTransaction().replace(R.id.containner, new SettingPreference())
		.commit();
	}
}

public class SettingPreference extends PreferenceFragment implements OnPreferenceChangeListener{
 
	private static Activity activity;
	private RingtonePreference mRingtone;
	private PreferenceScreen mPreferenceScreen;
	private static final String KEY_RINGTONE = "key_ringtone_preference";
	@Override
	public void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		addPreferencesFromResource(R.xml.generalpreference);
		activity = getActivity();
		mPreferenceScreen =  getPreferenceScreen();
		mRingtone = (RingtonePreference) mPreferenceScreen.findPreference(KEY_RINGTONE);
		String ringtoneUri = getRingtonePreference();
		String ringtone = getRingtoneTitleFromUri(ringtoneUri);
		mRingtone.setSummary(ringtone == null? "":ringtone); 
		//设置监听事件
		mRingtone.setOnPreferenceChangeListener(this);
		
	}
	/**
	 * 首选项值改变时回调
	 */
	@Override
	public boolean onPreferenceChange(Preference preference, Object newValue) {
		// TODO Auto-generated method stub
		if(preference == mRingtone){
			Toast.makeText(getActivity(), "newValue="+newValue, Toast.LENGTH_SHORT).show();
			setRingtonePreference((String)newValue);
			String ringtongTitle = getRingtoneTitleFromUri((String)newValue);
			mRingtone.setSummary(ringtongTitle);
		}
		return true;
	}
	
	/**
	 * 得到铃声的Uri
	 * @return
	 */
	public static String getRingtonePreference(){
		
		SharedPreferences prefs = activity.getSharedPreferences("SP", Context.MODE_PRIVATE);
		String ringtone = prefs.getString(KEY_RINGTONE, null);
		return ringtone;
		
	}
	/**
	 * 将铃声的Uri进行存储
	 * @param str
	 */
	public static void setRingtonePreference(String str){
		SharedPreferences prefs = activity.getSharedPreferences("SP", Context.MODE_PRIVATE);
		prefs.edit().putString(KEY_RINGTONE, str).commit();
	}
	
	/**
	 * 获取铃声名
	 * @param uri
	 * @return
	 */
	public static String getRingtoneTitleFromUri(String uri){
		if(TextUtils.isEmpty(uri)){
			return null;
		}
		Ringtone ringtone = RingtoneManager.getRingtone(activity, Uri.parse(uri));
		String ringtoneTitle = ringtone.getTitle(activity);
		return ringtoneTitle;
		
	}
}