异步加载图片-代码保留

1. 异步加载

public class MainActivity extends Activity {

private ArrayList<Bean> beans = new ArrayList<Bean>();
ImageAdapter adapter ;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        for (int i = 0; i < 15; i++)
{
Bean bean = new Bean();

// 初始为本地icon图片 
bean.setBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.icon));
        beans.add(bean);
}
        
        adapter = new ImageAdapter();
        ListView listView = new ListView(this);
        listView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
        setContentView(listView);

       //  构造时，传入adapter，用户更新数据UI
        new ImageLoadTask(this, adapter).execute();

}

class Bean
{
private Bitmap bitmap;

public void setBitmap(Bitmap bitmap)
{
this.bitmap = bitmap;
return ;
}

public Bitmap getBitmap()
{
return bitmap;

}

}
    
class ImageAdapter extends BaseAdapter
{


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


@Override
public Bean getItem(int position)
{
// TODO Auto-generated method stub
return beans.get(position);
}


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


@Override
public View getView(int position, View convertView, ViewGroup parent)
{
ImageView img = new ImageView(MainActivity.this);
Bean b = beans.get(position);
if ( b.getBitmap() != null)
{
img.setImageBitmap(b.getBitmap());
}
 
return img;
}


}
// 异步线程
class ImageLoadTaskextends AsyncTask
{
ImageAdapter adapter;


public ImageLoadTask(Context context, ImageAdapter adapter)
{
this.adapter = adapter;
}

@Override
protected Object doInBackground(Object... params)
{
for (int i = 0; i < adapter.getCount(); i++)
{
Bean b =  adapter.getItem(i);
Bitmap bitmap = BitmapFactory.decodeStream(Request.HandlerData
("http://avatar.profile.csdn.net/A/E/5/2_piaopiaohu123.jpg"));  // url

b.setBitmap(bitmap);

// 更新UI，调用onProgressUpdate
publishProgress();

}

return null;
}


@Override
protected void onProgressUpdate(Object... values)
{
adapter.notifyDataSetChanged();
}

}

}

  2.   // 从网络中获取数据流

public class Request {
   public static InputStream HandlerData(String url) {
      InputStream inStream=null;


      try {
          URL feedUrl = new URL(url);
      //    URLConnection conn = feedUrl.openConnection();
      //    conn.setConnectTimeout(10 * 1000);
      //    inStream = conn.getInputStream();

// 或者可以这样使用url读取网络图片

       inStream = feedUrl.openStream();

      } catch (Exception e) {
      Log.i("bitmap","exception");
          e.printStackTrace();
      }
      
      return inStream;
   }
}

3. AndroidManifext.xml文件中添加访问网络的权限

<uses-permission android:name="android.permission.INTERNET" />