How to fetch album and artist info. I wanna know what does this code do?

Question

Could someone please explain this to me line by line?I don't want to just copy paste stuffs without having proper knowledge about what i am actually doing

Uri sArtworkUri = Uri.parse("content://media/external/audio/albumart");
Uri uri = ContentUris.withAppendedId(sArtworkUri, album_id);
ContentResolver res = context.getContentResolver();
InputStream in = res.openInputStream(uri);
Bitmap artwork = BitmapFactory.decodeStream(in);

i am trying to use the code above in the code below to fetch music artists and album etc............................

.................................... ...................... ...........................

public ArrayList<SongDetails> getSongsFromDirectory(File f)
        {MediaMetadataRetriever mmr = new MediaMetadataRetriever();
            ArrayList<SongDetails> songs = new ArrayList<SongDetails>();
            if (!f.exists() || !f.isDirectory()) 

            {    
                return songs;
            }
            File[] files = f.listFiles(new Mp3Filter());
            for(int i=0; i<files.length; i++) 
            { 
                Uri uri = Uri.fromFile(files[i]);
                //mmr.setDataSource(null, uri);

            if (files[i].isFile()){ 
            SongDetails detail=new SongDetails(); 
            detail.setIcon(R.drawable.ic_launcher); 

            detail.setSong(files[i].getName()); 
            //detail.setArtist(mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ARTIST)); 
            //detail.setAlbum(mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ALBUM)); 
            songs.add(detail); 
            }else if (files[i].isDirectory()){ 
            songs.addAll(getSongsFromDirectory(files[i])); 
            } 

            }

            return songs;



    } }

Answer 1

Uri sArtworkUri = Uri.parse("content://media/external/audio/albumart");

This line will, "Creates a Uri which parses the given encoded URI string." (from http://developer.android.com/reference/android/net/Uri.html) A URI is a uniform resource identifier which is unique indentifier for a web resource.

Uri uri = ContentUris.withAppendedId(sArtworkUri, album_id);

ContentUris is a, "Utility methods useful for working with Uri objects that use the "content" (content://) scheme." (http://developer.android.com/reference/android/content/ContentUris.html) with appender ID appends the album_id to the end of the passed in URI. Essentially you're making a new URI to point directly to the album.

ContentResolver res = context.getContentResolver();

Provides access to content model (http://developer.android.com/reference/android/content/ContentResolver.html)

InputStream in = res.openInputStream(uri);

This gives you access to content at URI via an InputStream. InputStreams allow you to read in data. http://developer.android.com/reference/java/io/InputStream.html

 Bitmap artwork = BitmapFactory.decodeStream(in);

Lastly this method will load the image at the URI from the input stream. So you now have the image available to you in memory.