在Android開發中使用Gallery實現“多級聯動”

之前我們曾向您介紹過在android中實現service動態更新UI界面，在UI設計中需要利用很多圖庫相冊軟件，而Gallery 是國外一個免費開源的、功能非常強大、有豐富的擴展圖庫相冊軟件。本文將講解利用兩個Gallery實現類似多級聯動的功能。

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。

Gallery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> 

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: }  

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:     }  

好了，這就是我們介紹的在android開發中使用Gallery實現“多級聯動”的教程，謝謝大家。