android Listview 图片加载

Question

嗨，我有一个包含图像和 TextView 的自定义 ListView ，我在适配器的 ListView 的 getview 中使用处理程序来加载图像，当所有图像都加载后，然后我改变手机的方向图像再次开始下载，我想阻止这个，即当所有图像都加载时，当方向改变时它不起作用。

public View getView(final int position, View convertView, ViewGroup parent) {
        final String imageurl = imageUrls.get(position);
        LayoutInflater inflate = LayoutInflater.from(context);
        View v = inflate.inflate(rowResId, parent, false);
        final ImageView image = (ImageView) v.findViewById(R.id.image);
        final ProgressBar progress = (ProgressBar) v
                .findViewById(R.id.progress);

        image.setVisibility(View.GONE);
        progress.setVisibility(View.VISIBLE);
        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message message) {
                System.out.println("Set image at" + position
                        + " Image Name :: " + imageurl);
                progress.setVisibility(View.GONE);
                image.setImageBitmap((Bitmap) message.obj);
                image.setVisibility(View.VISIBLE);
            }
        };

        Thread thread = new Thread() {
            @Override
            public void run() {
                Bitmap drawable = LoadImageFromWebOperations(imageurl);
                Message message = handler.obtainMessage(1, drawable);
                handler.sendMessage(message);

            }
        };
        thread.start();
        return v;
    }

Answer 1

您可以使用位图图像列表。首先将列表中的所有位图设置为空。并在 getView 方法中检查 Bitmap 列表位置的 Bitmap 是否为 null。如果为 null，则显示进度条并下载图像并将图像保存在列表中。

例如图像列表名称是图像。那么getView方法中的代码将如下所示:

public View getView(final int position, View convertView, ViewGroup parent) {
    final String imageurl = imageUrls.get(position);
    LayoutInflater inflate = LayoutInflater.from(context);
    View v = inflate.inflate(rowResId, parent, false);
    final ImageView image = (ImageView) v.findViewById(R.id.image);
    final ProgressBar progress = (ProgressBar) v
            .findViewById(R.id.progress);
    if(images.get(position) != null) {
         progress.setVisibility(View.GONE);
         image.setImageBitmap(images.get(position));
         image.setVisibility(View.VISIBLE);
    } else {
         image.setVisibility(View.GONE);
         progress.setVisibility(View.VISIBLE);
         final Handler handler = new Handler() {
             @Override
             public void handleMessage(Message message) {
                  System.out.println("Set image at" + position
                    + " Image Name :: " + imageurl);
                  progress.setVisibility(View.GONE);
                  image.setImageBitmap((Bitmap) message.obj);
                  image.setVisibility(View.VISIBLE);
             }
         };

         Thread thread = new Thread() {
         @Override
            public void run() {
               Bitmap drawable = LoadImageFromWebOperations(imageurl);
               images.add(position, drawable);
               Message message = handler.obtainMessage(1, drawable);
               handler.sendMessage(message);
            }
         };
         thread.start();
    }

    return v;
}

希望您已经理解我的意思。 :)