多图片后台下载适配器 （多线程 后台下载图片）

[android]代码库

public class ImageListAdapter extends BaseAdapter {
    private Context context;
    private String[] myImages = null;
    public ImageListAdapter (Context context, String[] myImages) {
        this.context = context;
        this.myImages = myImages;
    }
    @Override
    public int getCount() {
        if (myImages == null) {
            return 0;
        }
        return myImages.length;
    }
    @Override
    public String getItem (int position) {
        if (position < 0 || myImages == null || position > myImages.length) {
            return null;
        }
        return myImages[position];
    }
    @Override
    public long getItemId (int position) {
        return position;
    }
    @Override
    public View getView (int position, View convertView, ViewGroup parent) {
        View item = null;
        if (convertView != null) {
            item = convertView;
        } else {
            item = View.inflate (context, R.layout.image_item, null);
        }
        final ImageView imageView = (ImageView) item.findViewById (R.id.image);
        final String image = getItem (position);
        if (image == null) {
            return item;
        }
        //对每个图片地址创建一个线程，
        new Thread() {
            public void run() {
                Message msg = new Message();
                msg.what = 0;
                //getBitmap省略了，就是从网上通过http下载图片，转化成一个Bitmap
                Bitmap bitmap = getBitmap (image);
                List list = new ArrayList();
                list.add (bitmap);
                list.add (imageView);
                msg.obj = list;
                handler.sendMessage (msg);
            }
        } .start();
        return item;
    }
    private Handler handler = new Handler() {
        @Override
        public void handleMessage (Message msg) {
            switch (msg.what) {
            case 0://接到从线程内传来的图片bitmap和imageView.
                //这里只是将bitmap传到imageView中就行了。只所以不在线程中做是考虑到线程的安全性。
                List list = (List) msg.obj;
                Bitmap bitmap = (Bitmap) list.get (0);
                ImageView iv = (ImageView) list.get (1);
                iv.setImageBitmap (bitmap);
                break;
            default:
                super.handleMessage (msg);
            }
        }
    };
}