为什么MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI没有提供准确的"专辑艺术家"？

Question

我正在使用android MediaStore.我可以在设备上获得音乐列表,以及与每个媒体项目相关的所有详细信息(标题,艺术家,持续时间等)

我希望能够通过他们的专辑艺术家展示专辑列表.

需要明确的是,每个轨道有一个艺术家,像"NOFX",但如果编辑CD上发生的轨迹,像朋克奥拉玛,艺术家是"NOFX",但专辑的艺术家可能会是这样的"群星. "

我在这里回顾了这个问题:

Android - 从Cursor获取专辑艺术家

我正在尝试使用MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI和MediaStore.Audio.Albums.ARTIST来实现.但是,这似乎没有返回正确的结果.

看看Android源代码,我可以看到事实上在MediaStore.Audio.Media.EXTERNAL_CONTENT_URI后面有一个album_artist字段,但它被标记为"@hide".(见行〜1170 https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/java/android/provider/MediaStore.java).

我发现这个领域通过其他[相关] Android源代码看: https://android.googlesource.com/platform/development/+/master/apps/Development/src/com/android/development/MediaScannerActivity.java

我写了一个简单的app/activity来测试这个:

package com.ma.albumartisttest;

import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.MediaStore;
import android.util.Log;
import android.util.SparseArray;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // query all media and get the album_artist field
        Cursor cursor = getContentResolver().query(
                MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                new String[]{MediaStore.Audio.Media.ALBUM_ID, "album_artist"}, null, null, null);

        // Store an id=>name map
        SparseArray<String> albumArtistNames = new SparseArray<String>();
        if (cursor != null) {
            for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
                String mediaAlbumArtist = cursor.getString(1);
                if (mediaAlbumArtist != null && mediaAlbumArtist.toLowerCase().contains("various")) {
                    // loop through the cursor, save "album_artist"s that look like "various"
                    albumArtistNames.put((int) cursor.getLong(0), mediaAlbumArtist);
                }
            }
            cursor.close();
        }

        String msg;
        if (albumArtistNames.size() == 0) {
            msg = "No 'various' artists found!";
            Log.d("TESTALBUMARTIST", msg);
        } else {
            StringBuffer out = new StringBuffer();
            for (int i = 0; i < albumArtistNames.size(); i++) {
                // loop through the albums found above
                int albumId = albumArtistNames.keyAt(i);
                String album_artist = albumArtistNames.get(albumId);
                Cursor albumCursor = getContentResolver().query(
                        MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI,
                        new String[]{MediaStore.Audio.Albums._ID, MediaStore.Audio.Albums.ARTIST},
                        MediaStore.Audio.Albums._ID + "=?",
                        new String[]{"" + albumId}, null);
                if (albumCursor != null) {
                    if (albumCursor.moveToFirst()) {
                        // print out what was found.
                        String artistFromAlbumsDB = albumCursor.getString(1);
                        Log.d("TESTALBUMARTIST", album_artist + ":" + artistFromAlbumsDB);
                        out.append("Album id: " + albumId).append('\n')
                                .append("Artist from media table: " + album_artist).append('\n')
                                .append("Artist from albums table: " + artistFromAlbumsDB)
                                .append("\n\n");
                    }
                    albumCursor.close();
                }
            }
            msg = out.toString();
        }

        // show the results on-screen
        TextView tv = new TextView(this);
        tv.setText(msg);
        setContentView(tv);
    }
}

此活动生成以下logcat输出:

12-20 14:16:45.688  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:Mike Garson
12-20 14:16:45.708  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:Franco Corelli
12-20 14:16:45.728  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:The Foreshadowing
12-20 14:16:45.748  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists - Polyvinyl Record Co:Volcano, I'm Still Excited!!
12-20 14:16:45.778  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists - Curve Music:GRAND:PM
12-20 14:16:45.808  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists - DiN:Ian Boddy
12-20 14:16:45.828  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:SNFU
12-20 14:16:45.858  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:Pulley
12-20 14:16:45.878  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:Osker
12-20 14:16:45.908  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:Pennywise
12-20 14:16:45.938  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:NoFX
12-20 14:16:45.958  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists:Death By Stereo
12-20 14:16:45.978  22009-22009/com.ma.albumartisttest D/TESTALBUMARTIST? Various Artists (Sillage Intemporel):Sheri Malckin

我在运行4.4.2的Nexus 7上运行它.我还测试并看到了运行4.1.1的华为Prism II上的相同行为

为什么没有让专辑艺术家工作的直截了当而不是"隐藏"的方式？

我期望的是专辑查询也会返回"各种艺术家".

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Answer 1

我没有看到您在代码中的任何地方定义或导入 ListActivity 。

看看这两个例子：

• 获取 MediaStore.Audio.Media 中指定项目的信息
• Android - 从光标获取专辑艺术家