android 用RingtonePreference显示副标题 summary的注意事项

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在用RingtonePreference显示副标题 summary，如果不实时更新副标题，即不实现OnPreferenceChangeListener接口时，系统会自动保存你所选择的提示音。如果需要实时更新副标题，必须实现OnPreferenceChangeListener接口，但在接口里需要手动保存所选的铃声，少说费话，代码如下，注意红色代码：

SettingsRing .java

import android.app.ActionBar;import android.app.Activity;import android.content.SharedPreferences;import android.media.Ringtone;import android.media.RingtoneManager;import android.net.Uri;import android.os.Bundle;import android.preference.Preference;import android.preference.PreferenceFragment;import android.preference.RingtonePreference;import android.preference.Preference.OnPreferenceChangeListener;import android.view.View;import android.view.View.OnClickListener;public class SettingsRing extends Activity {    // private ListView mListView = null;    // private ArrayAdapter<String> mAdapter;    // private boolean mCheckedItem[];    // private SystemConfig mConfig;        @Override    protected void onCreate(Bundle savedInstanceState) {        // TODO Auto-generated method stub        super.onCreate(savedInstanceState);        getFragmentManager().beginTransaction()                .replace(android.R.id.content, new PrefsFragement()).commit(); //显示PreferenceFragment界面    }    public static class PrefsFragement extends PreferenceFragment implements            OnPreferenceChangeListener {        private static final String KEY_RING_TONE = "ringtone";        private RingtonePreference mRingTone;        @Override        public void onCreate(Bundle savedInstanceState) {            // TODO Auto-generated method stub            super.onCreate(savedInstanceState);            addPreferencesFromResource(R.xml.preference);            mRingTone = (RingtonePreference) findPreference(KEY_RING_TONE);            Uri uri = Uri.parse(mRingTone.getSharedPreferences().getString(                    KEY_RING_TONE, ""));            mRingTone.setSummary(getRingtonName(uri));            mRingTone.setOnPreferenceChangeListener(this);        }        @Override        public boolean onPreferenceChange(Preference preference, Object newValue) {            // TODO Auto-generated method stub            if (preference == mRingTone) {                preference.setSummary(getRingtonName(Uri.parse(newValue.toString())));                // 此处必须加上，否则不会保存                SharedPreferences sp = preference.getPreferenceManager().getSharedPreferences();                sp.edit().putString(preference.getKey(), newValue.toString()).commit();            }            return false;        }        // 获取提示音名称        public String getRingtonName(Uri uri) {            Ringtone r = RingtoneManager.getRingtone(getActivity(), uri);            return r.getTitle(getActivity());        }    }

preference.xml

<?xml version="1.0" encoding="utf-8"?><PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >    <PreferenceCategory android:title="设置提示音" >        <RingtonePreference            android:key="ringtone"            android:showDefault="true"            android:showSilent="true"            android:title="提示音" />    </PreferenceCategory></PreferenceScreen>

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