如何使用asyncTask從資源加載圖像

在此自定義適配器中，在我的列表視圖中，只有一個imageview。我正在加載列表視圖中的圖像列表。我想加載新的圖像在asynctask但idont知道如何實現asynctask和大多數教程是指圖像下載，但我使用drawable資源，所以請指導我通過這個如何實現異步加載圖像替換當前可見視圖。如何使用asyncTask從資源加載圖像

class MyAdapter extends BaseAdapter { 

    private Context context; 
    private int images[]; 

    public MyAdapter(Context context, int images[]) { 
     this.context = context; 
     this.images = images; 
    } 

    @Override 
    public int getCount() { 
     // TODO Auto-generated method stub 
     return images.length; 
    } 

    @Override 
    public Object getItem(int position) { 
     // TODO Auto-generated method stub 
     return images[position]; 
    } 

    @Override 
    public long getItemId(int position) { 
     // TODO Auto-generated method stub 
     return position; 
    } 

    class MyViewHolder { 
     ImageView imageView; 

     public MyViewHolder(View v) { 
      // TODO Auto-generated constructor stub 
      imageView = (ImageView) v.findViewById(R.id.imgView); 
     } 
    } 

    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
     // TODO Auto-generated method stub 
     View row = convertView; 
     MyViewHolder holder = null; 
     if (row == null) { 
      LayoutInflater inflater = (LayoutInflater) context 
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      row = inflater.inflate(R.layout.custom_list, parent, false); 

      holder = new MyViewHolder(row); 
      row.setTag(holder); 
     } else { 
      holder = (MyViewHolder) row.getTag(); 
      row = convertView; 
     } 
     holder.imageView.setImageResource(images[position]); 
     return row; 
    } 
}

這裏是我的MainActivity，我打電話給MyAdapter獲取圖像列表。

public class MainActivity extends Activity { 

    private ListView listView; 
    private MyAdapter myAdapter; 

    int[] images = { R.drawable.img001, R.drawable.img002, R.drawable.img003, 
      R.drawable.img004, R.drawable.img005, R.drawable.img006, 
      R.drawable.img007, R.drawable.img008, R.drawable.img009, 
      R.drawable.img010, R.drawable.img011, R.drawable.img012, 
      R.drawable.img013, R.drawable.img014, R.drawable.img015, 
      R.drawable.img016, R.drawable.img017, R.drawable.img018, 
      R.drawable.img019, R.drawable.img020, R.drawable.img021, 
      R.drawable.img022, R.drawable.img023, R.drawable.img024, 
      R.drawable.img025, R.drawable.img026, R.drawable.img027, 
      R.drawable.img028, R.drawable.img029, R.drawable.img030, 
      R.drawable.img031, R.drawable.img032, R.drawable.img033, 
      R.drawable.img034, R.drawable.img035, R.drawable.img036, 
      R.drawable.img037, R.drawable.img038, R.drawable.img039, 
      R.drawable.img040, R.drawable.img041, R.drawable.img042, 
      R.drawable.img043, R.drawable.img044, R.drawable.img045, 
      R.drawable.img046, R.drawable.img047, R.drawable.img048, 
      R.drawable.img049, R.drawable.img050, R.drawable.img051, 
      R.drawable.img052, R.drawable.img053, R.drawable.img054, 
      R.drawable.img055, R.drawable.img056, R.drawable.img057, 
      R.drawable.img058, R.drawable.img059, R.drawable.img060, 
      R.drawable.img061, R.drawable.img062, R.drawable.img063, 
      R.drawable.img064, R.drawable.img065, R.drawable.img066, 
      R.drawable.img067, R.drawable.img068, R.drawable.img069, 
      R.drawable.img070, R.drawable.img071, R.drawable.img072, 
      R.drawable.img073, R.drawable.img074, R.drawable.img075, 
      R.drawable.img076, R.drawable.img077, R.drawable.img078, 
      R.drawable.img079, R.drawable.img080, R.drawable.img081, 
      R.drawable.img082, R.drawable.img083, R.drawable.img084, 
      R.drawable.img085, R.drawable.img086, R.drawable.img087, 
      R.drawable.img088, R.drawable.img089, R.drawable.img090, 
      R.drawable.img091, R.drawable.img092, R.drawable.img093, 
      R.drawable.img094, R.drawable.img095, R.drawable.img096, 
      R.drawable.img097, R.drawable.img098, R.drawable.img099, 
      R.drawable.img100 }; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main);  
     myAdapter = new MyAdapter(this, images); 
     listView = (ListView) findViewById(R.id.imgList); 
     listView.setAdapter(myAdapter); 
    } 
    }

來源

2014-09-10 Faisal Asif

爲什麼要用asynctasks「裝入」可繪製該已經在資源上了？ – 2014-09-10 15:23:36

，因爲解碼位圖需要時間並凍結UI線程。 @Pedro Oliveira – Snicolas 2014-09-10 15:29:02

dependencies { 
    compile 'com.squareup.picasso:picasso:2.3.2' 
} 

Picasso.with(context).load(R.drawable.<id>).into(holder.imageView);

來源

2014-09-10 15:33:18 mbmc

我使用了這條語句，但它在日誌和應用程序崩潰時出現以下錯誤：「3318016-字節分配內存不足」 – 2014-09-10 15:49:21

如果您知道圖片的屏幕尺寸，則可以調整其大小「Picasso」。（）。load（）。resize（，）.into（）;'或者自動縮放'Picasso.with（）.load（）.fit（）。into（）;' – mbmc 2014-09-10 15:54:29

它仍然給出相同的錯誤可以üplz描述確切地說我應該在上面的自定義適配器中調用此語句的位置？ – 2014-09-10 16:13:28

這裏有一個完整的例子：http://developer.android.com/training/displaying-bitmaps/process-bitmap.html

正是你所需要的。但是如果你開始使用Android，這段代碼真的很複雜。更好的建議是使用這個庫，並有一些選擇：

RoboSpice UI list module
picasso（事實上的標準）
glide

來源

2014-09-10 15:34:11 Snicolas

是的，你是儀式，關閉UI線程處理位圖是非常複雜的理解，但我仍然想使用這個，你可以指導我如何在上面的鱈魚上實現這一點。 – 2014-09-11 11:19:06

如何使用asyncTask從資源加載圖像

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