扣丁音乐（四）——本地音乐加载

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本文出自：http://blog.csdn.net/dt235201314/article/details/51341078

一丶本地音乐加载相当于就是listVIew应用

扣丁音乐1.0前部分（gif图大小限制）演示：

实体类Mp3Info（歌曲相关数据及get和set方法）

public class Mp3Info {
    private long id;
    private String title;//歌名
    private String artist;//艺术家
    private String album;//专辑
    private long albumId;
    private long duration;//时长
    private long size;//大小
    private String url;//路径
    private int isMusic;//是否为音乐
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getArtist() {
        return artist;
    }

    public void setArtist(String artist) {
        this.artist = artist;
    }

    public String getAlbum() {
        return album;
    }

    public void setAlbum(String album) {
        this.album = album;
    }

    public long getAlbumId() {
        return albumId;
    }

    public void setAlbumId(long albumId) {
        this.albumId = albumId;
    }

    public long getDuration() {
        return duration;
    }

    public void setDuration(long duration) {
        this.duration = duration;
    }

    public long getSize() {
        return size;
    }

    public void setSize(long size) {
        this.size = size;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public int getIsMusic() {
        return isMusic;
    }

    public void setIsMusic(int isMusic) {
        this.isMusic = isMusic;
    }

    @Override
    public String toString() {
        return "Mp3Info{" +
                "id=" + id +
                ", title=‘" + title + ‘\‘‘ +
                ", artist=‘" + artist + ‘\‘‘ +
                ", album=‘" + album + ‘\‘‘ +
                ", albumId=" + albumId +
                ", duration=" + duration +
                ", size=" + size +
                ", url=‘" + url + ‘\‘‘ +
                ", isMusic=" + isMusic +
                ‘}‘;
    }
}

public class MediaUtils {

    //获取专辑封面的Uri
    private static final Uri albumArtUri = Uri.parse("content://media/external/audio/albumart");

    /**
     * 获取默认专辑图片
     */
    public static Bitmap getDefaultArtwork(Context context,boolean small){
        BitmapFactory.Options opts = new BitmapFactory.Options();
        opts.inPreferredConfig = Bitmap.Config.RGB_565;
        if(small){
            return BitmapFactory.decodeStream(context.getResources().openRawResource(R.drawable.music_play),null,opts);
        }
        return BitmapFactory.decodeStream(context.getResources().openRawResource(R.drawable.music_play),null,opts);
    }

    /**
     * 从文件当中获取专辑封面位图
     */
    private static Bitmap getArtworkFromFile(Context context,long songid,long albumid){
        Bitmap bm = null;
        if(albumid<0 && songid<0){
            throw new IllegalArgumentException("Must specify an album or a song id");
        }
        try {
            BitmapFactory.Options options = new BitmapFactory.Options();
            FileDescriptor fd = null;
            if(albumid<0){
                Uri uri = Uri.parse("content://media/external/audio/media"
                        +songid+"albumart");
                ParcelFileDescriptor pfd = context.getContentResolver().openFileDescriptor(uri,"r");
                if(pfd!=null){
                    fd = pfd.getFileDescriptor();
                }
            }else{
                Uri uri = ContentUris.withAppendedId(albumArtUri,albumid);
                ParcelFileDescriptor pfd = context.getContentResolver().openFileDescriptor(uri, "r");
                if(pfd!=null){
                    fd = pfd.getFileDescriptor();
                }
            }
            options.inSampleSize=1;
            //只进行大小判断
            options.inJustDecodeBounds = true;
            //调用此方法得到options得到图片大小
            BitmapFactory.decodeFileDescriptor(fd,null,options);
            //我们的目标是在800pixel的画面上显示
            //所以需要调用computeSampleSize得到图片缩放的比例
            options.inSampleSize = 100;
            //我们得到了缩放的比例，现在开始正式读入Bitmap数据
            options.inJustDecodeBounds = false;
            options.inDither = false;
            options.inPreferredConfig = Bitmap.Config.ARGB_8888;

            //根据options参数，减少所需要的内存
            bm = BitmapFactory.decodeFileDescriptor(fd,null,options);
        }catch (FileNotFoundException e){
            e.printStackTrace();
        }
        return bm;
    }

    /**
     * 获取专辑封面位图对象
     */
    public static Bitmap getArtwork(Context context,long song_id,long album_id,boolean allowdefault,boolean small){
        if(album_id<0){
            if(song_id<0){
                Bitmap bm = getArtworkFromFile(context,song_id,-1);
                if(bm!=null){
                    return bm;
                }
            }
            if(allowdefault){
                return getDefaultArtwork(context,small);
            }
            return null;
        }
        ContentResolver res = context.getContentResolver();
        Uri uri = ContentUris.withAppendedId(albumArtUri,album_id);
        if(uri !=null){
            InputStream in = null;
            try {
                in = res.openInputStream(uri);
                BitmapFactory.Options options = new BitmapFactory.Options();
                //先指定原始大小
                options.inSampleSize = 1;
                //只进行大小判断
                options.inJustDecodeBounds = true;
                //调用此方法得到options得到图片的大小
                BitmapFactory.decodeStream(in,null,options);
                //我们的目标是在你N pixel的画面上显示。所以需要调用computeSampleSize得到图片缩放的比例
                //这里的target为800是根据默认专辑图片代傲决定的，800只是测试数字但是试验后发现完美的结合
                if(small){
                    options.inSampleSize = computeSampleSize(options,40);
                }else {
                    options.inSampleSize = computeSampleSize(options,600);
                }
                //我们得到了缩放比例，现在开始正式读入Bitmap数据
                options.inJustDecodeBounds = false;
                options.inDither = false;
                options.inPreferredConfig = Bitmap.Config.ARGB_8888;
                in = res.openInputStream(uri);
                return BitmapFactory.decodeStream(in,null,options);
            }catch (FileNotFoundException e){
                Bitmap bm = getArtworkFromFile(context,song_id,album_id);
                if(bm!=null){
                    if(bm.getConfig()==null){
                        bm = bm.copy(Bitmap.Config.RGB_565,false);
                        if(bm == null && allowdefault){
                            return getDefaultArtwork(context,small);
                        }
                    }else if(allowdefault){
                        bm = getDefaultArtwork(context,small);
                    }
                    return bm;
                }
            }finally {
                try {
                    if(in != null){
                        in.close();
                    }
                }catch (IOException e){
                    e.printStackTrace();
                }
            }
        }
        return null;
    }

    /**
     * 对图片进行合适的缩放
     */
    public static int computeSampleSize(BitmapFactory.Options options,int target){
        int w = options.outWidth;
        int h = options.outHeight;
        int candidateW = w / target;
        int candidateH = h / target;
        int candidate = Math.max(candidateW,candidateH);
        if(candidate == 0){
            return 1;
        }
        if (candidate>1){
            if((w>target)&&(w/candidate)<target){
                candidate -= -1;
            }
        }
        if(candidate>1){
            if((h>target)&&(h/candidate)<target){
                candidate -= -1;
            }
        }
        return candidate;
    }

    /**
     * 用于从数据库中查询歌曲的信息，保存在List当中
     */
    public static ArrayList<Mp3Info> getMp3Infos(Context context){
        Cursor cursor = context.getContentResolver().query(
                MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null,
                //最小音乐长度
                MediaStore.Audio.Media.DURATION + ">=180000", null,
                MediaStore.Audio.Media.DEFAULT_SORT_ORDER);

        ArrayList<Mp3Info> mp3Infos = new ArrayList<Mp3Info>();
        for(int i=0;i<cursor.getCount();i++){
            cursor.moveToNext();
            Mp3Info mp3Info = new Mp3Info();
            long id = cursor.getLong(cursor.getColumnIndex(MediaStore.Audio.Media._ID));//id
            String title = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE));//歌名
            String artist = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST));//艺术家
            String album = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM));//专辑
            long albumId = cursor.getLong(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));//专辑id
            long duration = cursor.getLong(cursor.getColumnIndex(MediaStore.Audio.Media.DURATION));//时长
            long size = cursor.getLong(cursor.getColumnIndex(MediaStore.Audio.Media.SIZE));//大小
            String url = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA));//路径
            int isMusic = cursor.getInt(cursor.getColumnIndex(MediaStore.Audio.Media.IS_MUSIC));//是否为音乐

            if(isMusic!=0){
                mp3Info.setId(id);
                mp3Info.setTitle(title);
                mp3Info.setArtist(artist);
                mp3Info.setAlbum(album);
                mp3Info.setAlbumId(albumId);
                mp3Info.setDuration(duration);
                mp3Info.setSize(size);
                mp3Info.setUrl(url);
                mp3Infos.add(mp3Info);
            }
        }

        cursor.close();
        return mp3Infos;
    }

    /**
     * 格式化时间，将毫秒转换为分：秒格式
     */
    public static String formatTime(long time){
        String min = time / (1000 * 60)+"";
        String sec = time % (1000 * 60)+"";
        if(min.length()<2){
            min = "0"+time / (1000 * 60)+"";
        }else{
            min = time / (1000 * 60)+"";
        }
        if(sec.length()==4){
            sec = "0"+(time % (1000 * 60))+"";
        }else if(sec.length()==3){
            sec = "00"+(time % (1000 * 60))+"";
        }else if(sec.length()==2){
            sec = "000"+(time % (1000 * 60))+"";
        }else if(sec.length()==1){
            sec = "0000"+(time % (1000 * 60))+"";
        }

        return min + ":" +sec.trim().substring(0,2);
    }}

item_music_fragment.xml（略）

很明显这里我和视频显示得不一样，歌曲图片不好找显示出来也不是很美观，于是我显示的是歌名，歌手，专辑，时间这个xml应个人喜好可调整

LocalSongsListAdapter.java

public class LocalSongsListAdapter extends BaseAdapter{

    private Context context;
    private ArrayList<Mp3Info> mp3Infos;

    public LocalSongsListAdapter(Context context,ArrayList<Mp3Info> mp3Infos){
        this.context = context;
        this.mp3Infos = mp3Infos;
    }

    public void setMp3Infos(ArrayList<Mp3Info> mp3Infos){
        this.mp3Infos = mp3Infos;
    }

    @Override
    public int getCount() {
        return mp3Infos.size();
    }

    @Override
    public Object getItem(int position) {
        return mp3Infos.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder vh;
        if(convertView==null){
            convertView = LayoutInflater.from(context).inflate(R.layout.item_music_list,null);
            vh = new ViewHolder();
            vh.tv_song_name = (TextView)convertView.findViewById(R.id.tv_song_name);
            vh.tv_song_artist = (TextView)convertView.findViewById(R.id.tv_song_artist);
            vh.tv_song_album = (TextView)convertView.findViewById(R.id.tv_song_album);
            vh.tv_song_duration = (TextView)convertView.findViewById(R.id.tv_song_duration);
            convertView.setTag(vh);
        }else{
            vh = (ViewHolder)convertView.getTag();
        }
        //给控件赋值要写在if语句外面，否则第一次加载数据失败
        Mp3Info mp3Info = mp3Infos.get(position);
        vh.tv_song_name.setText(mp3Info.getTitle());
        vh.tv_song_artist.setText(mp3Info.getArtist());
        vh.tv_song_album.setText(mp3Info.getAlbum());
        vh.tv_song_duration.setText(MediaUtils.formatTime(mp3Info.getDuration()));

        return convertView;
    }

    static class ViewHolder{
        TextView tv_song_name;
        TextView tv_song_artist;
        TextView tv_song_album;
        TextView tv_song_duration;
    }
}

写到这里LocalSongsActivity.java里面只需要初始化控件，后面再贴出

/**
 * 初始化本地音乐列表
 */
private void initDate() {
    mp3Infos = MediaUtils.getMp3Infos(this);
    System.out.println(mp3Infos.size());
    localSongsListAdapter = new LocalSongsListAdapter(this,mp3Infos);
    localSongsListAdapter.notifyDataSetChanged();
    lv_local_songs_list.setAdapter(localSongsListAdapter);

}

SD卡读取权限，网络权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.INTERNET"></uses-permission>

到这里就能完成歌曲的加载了

扣丁音乐（四）——本地音乐加载

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原文地址：http://blog.csdn.net/dt235201314/article/details/51341078