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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.musicplayer;
     18 
     19 import android.content.ContentResolver;
     20 import android.content.ContentUris;
     21 import android.database.Cursor;
     22 import android.net.Uri;
     23 import android.provider.MediaStore;
     24 import android.util.Log;
     25 
     26 import java.util.ArrayList;
     27 import java.util.List;
     28 import java.util.Random;
     29 
     30 /**
     31  * Retrieves and organizes media to play. Before being used, you must call {@link #prepare()},
     32  * which will retrieve all of the music on the user's device (by performing a query on a content
     33  * resolver). After that, it's ready to retrieve a random song, with its title and URI, upon
     34  * request.
     35  */
     36 public class MusicRetriever {
     37     final String TAG = "MusicRetriever";
     38 
     39     ContentResolver mContentResolver;
     40 
     41     // the items (songs) we have queried
     42     List<Item> mItems = new ArrayList<Item>();
     43 
     44     Random mRandom = new Random();
     45 
     46     public MusicRetriever(ContentResolver cr) {
     47         mContentResolver = cr;
     48     }
     49 
     50     /**
     51      * Loads music data. This method may take long, so be sure to call it asynchronously without
     52      * blocking the main thread.
     53      */
     54     public void prepare() {
     55         Uri uri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
     56         Log.i(TAG, "Querying media...");
     57         Log.i(TAG, "URI: " + uri.toString());
     58 
     59         // Perform a query on the content resolver. The URI we're passing specifies that we
     60         // want to query for all audio media on external storage (e.g. SD card)
     61         Cursor cur = mContentResolver.query(uri, null,
     62                 MediaStore.Audio.Media.IS_MUSIC + " = 1", null, null);
     63         Log.i(TAG, "Query finished. " + (cur == null ? "Returned NULL." : "Returned a cursor."));
     64 
     65         if (cur == null) {
     66             // Query failed...
     67             Log.e(TAG, "Failed to retrieve music: cursor is null :-(");
     68             return;
     69         }
     70         if (!cur.moveToFirst()) {
     71             // Nothing to query. There is no music on the device. How boring.
     72             Log.e(TAG, "Failed to move cursor to first row (no query results).");
     73             return;
     74         }
     75 
     76         Log.i(TAG, "Listing...");
     77 
     78         // retrieve the indices of the columns where the ID, title, etc. of the song are
     79         int artistColumn = cur.getColumnIndex(MediaStore.Audio.Media.ARTIST);
     80         int titleColumn = cur.getColumnIndex(MediaStore.Audio.Media.TITLE);
     81         int albumColumn = cur.getColumnIndex(MediaStore.Audio.Media.ALBUM);
     82         int durationColumn = cur.getColumnIndex(MediaStore.Audio.Media.DURATION);
     83         int idColumn = cur.getColumnIndex(MediaStore.Audio.Media._ID);
     84 
     85         Log.i(TAG, "Title column index: " + String.valueOf(titleColumn));
     86         Log.i(TAG, "ID column index: " + String.valueOf(titleColumn));
     87 
     88         // add each song to mItems
     89         do {
     90             Log.i(TAG, "ID: " + cur.getString(idColumn) + " Title: " + cur.getString(titleColumn));
     91             mItems.add(new Item(
     92                     cur.getLong(idColumn),
     93                     cur.getString(artistColumn),
     94                     cur.getString(titleColumn),
     95                     cur.getString(albumColumn),
     96                     cur.getLong(durationColumn)));
     97         } while (cur.moveToNext());
     98 
     99         Log.i(TAG, "Done querying media. MusicRetriever is ready.");
    100     }
    101 
    102     public ContentResolver getContentResolver() {
    103         return mContentResolver;
    104     }
    105 
    106     /** Returns a random Item. If there are no items available, returns null. */
    107     public Item getRandomItem() {
    108         if (mItems.size() <= 0) return null;
    109         return mItems.get(mRandom.nextInt(mItems.size()));
    110     }
    111 
    112     public static class Item {
    113         long id;
    114         String artist;
    115         String title;
    116         String album;
    117         long duration;
    118 
    119         public Item(long id, String artist, String title, String album, long duration) {
    120             this.id = id;
    121             this.artist = artist;
    122             this.title = title;
    123             this.album = album;
    124             this.duration = duration;
    125         }
    126 
    127         public long getId() {
    128             return id;
    129         }
    130 
    131         public String getArtist() {
    132             return artist;
    133         }
    134 
    135         public String getTitle() {
    136             return title;
    137         }
    138 
    139         public String getAlbum() {
    140             return album;
    141         }
    142 
    143         public long getDuration() {
    144             return duration;
    145         }
    146 
    147         public Uri getURI() {
    148             return ContentUris.withAppendedId(
    149                     android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, id);
    150         }
    151     }
    152 }
    153