Android開發——使用Gallery實現“多級聯動”

： ，一個Gallery是歌曲專輯圖片，另一個Gallery是專輯的歌曲。滑動專輯Gallery，下面的歌曲也會隨之發生變動。

一、布局。

主要的布局是有兩個相對布局+兩個Gallery組成的：

   1: <?xml version="1.0" encoding="utf-8"?>

   2: <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 

   3:     android:layout_width="fill_parent" 

   4:     android:layout_height="fill_parent"> 

   5:     <!-- 專輯 -->

   6:     <Gallery android:id="@+id/gallery"

   7:         android:layout_width="fill_parent"

   8:         android:layout_height="wrap_content"

   9:         android:layout_alignParentTop="true"

  10:         android:gravity="center_horizontal"

  11:         android:spacing="16dp"

  12:         android:unselectedAlpha="0.5"/>

  13:     <!-- 歌曲 -->

  14:     <Gallery android:id="@+id/gallery2"

  15:         android:background="#FFF"

  16:         android:layout_width="fill_parent"

  17:         android:layout_height="30dp"

  18:         android:layout_below="@id/gallery"

  19:         android:layout_alignParentLeft="true"

  20:         android:gravity="center_vertical"

  21:         android:spacing="16dp"

  22:         android:unselectedAlpha="0.5" />

  23: </RelativeLayout>

 

二、Gallery的適配器

在android中適配器很好的實現了MVC思想，它很好的為某些組件提供了數據和view的實現。此處我們需要通過繼承BaseAdapter，實現兩個Gallery的適配器。

   1: /**

   2:  * 專輯

   3:  * 

   4:  * @author halzhang

   5:  */

   6: public class AlbumAdapter extends BaseAdapter {

   7:  

   8:     private Context context;

   9:  

  10:     private Cursor cursor;

  11:  

  12:     private Bitmap[] bitmaps;

  13:  

  14:     public AlbumAdapter(Context context) {

  15:         this.context = context;

  16:         this.cursor = context.getContentResolver().query(

  17:                 MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI, null, null, null,

  18:                 MediaStore.Audio.Albums.DEFAULT_SORT_ORDER);

  19:         bitmaps = new Bitmap[cursor.getCount()];

  20:         initBitmaps();

  21:     }

  22:  

  23:     /**

  24:      * 初始化專輯封面圖片

  25:      */

  26:     private void initBitmaps() {

  27:         if (cursor.moveToFirst()) {

  28:             do {

  29:                 bitmaps[cursor.getPosition()] = MusicUtils.getArtwork(context, -1, cursor

  30:                         .getInt(cursor.getColumnIndexOrThrow(MediaStore.Audio.Albums._ID)));

  31:             } while (cursor.moveToNext());

  32:         }

  33:     }

  34:  

  35:     public int getCount() {

  36:         if (cursor != null) {

  37:             return cursor.getCount();

  38:         }

  39:         return 0;

  40:     }

  41:  

  42:     public Object getItem(int position) {

  43:         return position;

  44:     }

  45:  

  46:     public long getItemId(int position) {

  47:         if (cursor != null) {

  48:             cursor.moveToPosition(position);

  49:             return cursor.getInt(cursor.getColumnIndexOrThrow(MediaStore.Audio.Albums._ID));

  50:         }

  51:         return 0;

  52:     }

  53:  

  54:     public View getView(int position, View convertView, ViewGroup parent) {

  55:         ImageView iv = new ImageView(context);

  56:         iv.setLayoutParams(new Gallery.LayoutParams(100, 100));

  57:         iv.setAdjustViewBounds(true);

  58:         iv.setImageBitmap(bitmaps[position]);

  59:         return iv;

  60:     }

  61:  

  62: }

------------------------------------------

   1: /**

   2:  * 歌曲

   3:  * 

   4:  * @author halzhang

   5:  */

   6: public class AudioAdapter extends BaseAdapter {

   7:  

   8:     private Context context;

   9:  

  10:     private Cursor cursor;

  11:     /**專輯ID*/

  12:     private int albumId;

  13:  

  14:     public AudioAdapter(Context context, int albumId) {

  15:         this.context = context;

  16:         this.albumId = albumId;

  17:         this.cursor = context.getContentResolver().query(

  18:                 MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null,

  19:                 MediaStore.Audio.Media.ALBUM_ID + "=" + albumId, null,

  20:                 MediaStore.Audio.Media.DEFAULT_SORT_ORDER);

  21:     }

  22:  

  23:     public int getCount() {

  24:         if (cursor != null) {

  25:             return cursor.getCount();

  26:         }

  27:         return 0;

  28:     }

  29:  

  30:     public Object getItem(int position) {

  31:         return position;

  32:     }

  33:  

  34:     public long getItemId(int position) {

  35:         if (cursor != null) {

  36:             cursor.moveToPosition(position);

  37:             return cursor.getInt(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media._ID));

  38:         }

  39:         return 0;

  40:     }

  41:  

  42:     public View getView(int position, View convertView, ViewGroup parent) {

  43:         cursor.moveToPosition(position);

  44:         TextView t = new TextView(context);

  45:         String title = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE));

  46:         t.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,

  47:                 LayoutParams.WRAP_CONTENT));

  48:         t.setText(title);

  49:         t.setTextColor(Color.BLACK);

  50:         return t;

  51:     }

  52:  

  53:     /**

  54:      * 當專輯改變了，調用此方法更新adapter的數據

  55:      * @param albumId 專輯ID

  56:      */

  57:     public void notifyDataSetChanged(int albumId) {

  58:         this.cursor = context.getContentResolver().query(

  59:                 MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null,

  60:                 MediaStore.Audio.Media.ALBUM_ID + "=" + albumId, null,

  61:                 MediaStore.Audio.Media.DEFAULT_SORT_ORDER);

  62:         super.notifyDataSetChanged();

  63:     }

  64:  

  65: }

 

三、Activity

   1: public class MainActivity extends Activity implements AdapterView.OnItemSelectedListener {

   2:  

   3:     private Gallery album;

   4:  

   5:     private Gallery audio;

   6:  

   7:     private AlbumAdapter albumAdapter;

   8:  

   9:     private AudioAdapter audioAdapter;

  10:  

  11:     @Override

  12:     protected void onCreate(Bundle savedInstanceState) {

  13:         super.onCreate(savedInstanceState);

  14:         setContentView(R.layout.audio_player);

  15:         setupViews();

  16:     }

  17:  

  18:     // 個人習慣

  19:     private void setupViews() {

  20:         album = (Gallery) findViewById(R.id.gallery);

  21:         audio = (Gallery) findViewById(R.id.gallery2);

  22:  

  23:         albumAdapter = new AlbumAdapter(this);

  24:  

  25:         album.setAdapter(albumAdapter);

  26:  

  27:         int aid = (int) albumAdapter.getItemId(0);

  28:  

  29:         audioAdapter = new AudioAdapter(this, aid);

  30:         audio.setAdapter(audioAdapter);

  31:  

  32:         audio.setOnItemSelectedListener(this);

  33:         album.setOnItemSelectedListener(this);

  34:     }

  35:  

  36:     public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

  37:         if (parent == album) {

  38:             // 專輯被選中

  39:             int aid = (int) albumAdapter.getItemId(position);

  40:             // 更新歌曲Gallery

  41:             audioAdapter.notifyDataSetChanged(aid);

  42:         } else if (parent == audio) {

  43:             // TODO do something

  44:         }

  45:  

  46:     }

  47:  

  48:     public void onNothingSelected(AdapterView<?> parent) {

  49:  

  50:     }

OK，代碼貼的有點多了。歡迎交流。

轉自：http://www.cnblogs.com/halzhang/archive/2010/08/07/1794555.html