Android--通过ContentResolver取得com.android.providers.media下的media信息

package cn.mrzhu.media;

import android.app.Activity;
import android.content.ContentResolver;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;

/**
* 通过ContentResolver取得com.android.providers.media下的media信息
* @author ZLQ
*
*/
public class TestMedia extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.media);
}

/**
* show按钮，点击按钮打印输出文件的标题，演唱者和专辑
* @param v
*/
public void show(View v) {
//指定到com.android.providers.media下的external_XXXdb，即存储卡数据库
Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
//audio_meta表的里_id，即文件的id
String _ID = MediaStore.Audio.Media._ID;
//audio_meta表的里title,即文件的标题
String TITLE = MediaStore.Audio.Media.TITLE;
//artist表的里artist_id,即演唱者的id
String ARTIST_ID = MediaStore.Audio.Media.ARTIST_ID;
//artist表的里artist_id,即演唱者的信息
String ARTIST = MediaStore.Audio.Media.ARTIST;
//album表的里album_id,即专辑的id
String ALBUM_ID = MediaStore.Audio.Media.ALBUM_ID;
//album表的里album_id,即专辑的信息
String ALBUM = MediaStore.Audio.Media.ALBUM;
//取得内容解析对象
ContentResolver cr = getContentResolver();
//调用query开始解析数据，返回一个Cursor结果集
Cursor cs = cr.query(uri, null, null, null, null);
while (cs.moveToNext()) {
//取得audio_meta表的里_id
String meta_id = cs.getString(cs.getColumnIndex(_ID));
//取得audio_meta表的里title
String title = cs.getString(cs.getColumnIndex(TITLE));
//用条件ARTIST_ID + "=" + meta_id + " and " + ALBUM_ID + "=" + meta_id
//从artist表和album表中找到与audio_meta表_id相对应的信息
Cursor c = cr.query(uri, null, ARTIST_ID + "=" + meta_id + " and " + ALBUM_ID + "=" + meta_id, null, null);
while(c.moveToNext()){
//打印输出文件的标题，演唱者和专辑
Log.i("System.out","title    " + title + "   artist  " + c.getString(c.getColumnIndex(ARTIST))
+ "   album   " + c.getString(c.getColumnIndex(ALBUM)));
}
}
}

/**
* scan按钮，点击按钮给系统发送广播，搜索sdcard卡下的所有音乐文件并更新数据库
* @param v
*/
public void scan(View v) {
Intent intent = new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://"
+ Environment.getExternalStorageDirectory()
.getAbsolutePath()));
sendBroadcast(intent);
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="scan"
android:text="scan" >
</Button>

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="show"
android:text="show" >
</Button>

</LinearLayout>