Android的排球 - 加载图像时，在适配器列表视图显示进度条 [英] Android Volley - Show progress bar in listview adapter when loading image

问题描述

我试着在列表视图项摆脱网络映像与排球。在下载图像，进度条是显示，完成后，应该躲起来。

I tried to get image from network with Volley in listview item. While downloading image, the progress bar is showing, when complete, it should be hide.

下面是我的适配器：

   public class NewsAdapter  extends CursorAdapter{
public NewsAdapter(Context context, Cursor c) {
    super(context, c, true);
}

@Override
public Cursor getItem(int position) {
    return (Cursor) super.getItem(position);
}

@Override
public void bindView(View view, final Context context, Cursor cursor) {
    final NetworkImageView imgNewsItem = (NetworkImageView) view.findViewById(R.id.imgNewsItem); 
    final ProgressBar progressNewsList = (ProgressBar) view.findViewById(R.id.progressNewsList);

    progressNewsList.setVisibility(View.VISIBLE);
    imgNewsItem.setVisibility(View.GONE);
    Ln.d("get news image: %s", cursor.getString(cursor.getColumnIndex(News.IMAGE_COLUMN)));
    ImageCacheManager.getInstance().getImageLoader().get(cursor.getString(cursor.getColumnIndex(News.IMAGE_COLUMN)), new ImageListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            Ln.e(error);
            progressNewsList.setVisibility(View.GONE);
            imgNewsItem.setVisibility(View.VISIBLE);
            imgNewsItem.setImageResource(R.drawable.news_default_image);
        }

        @Override
        public void onResponse(ImageContainer response, boolean isImmediate) {
            progressNewsList.setVisibility(View.GONE);
            imgNewsItem.setVisibility(View.VISIBLE);
            imgNewsItem.setImageBitmap(response.getBitmap());
        }
    });
}

@Override
public View newView(Context arg0, Cursor arg1, ViewGroup parent) {
    LayoutInflater inflater = LayoutInflater.from(parent.getContext());
    View retView = inflater.inflate(R.layout.row_view, parent, false);
    return retView;
}

}

我已经调试，发现乱射下载和缓存位图图像是好的，但图像视图不显示。

I have debugged and found that Volley download and cache image bitmap is ok, but the image view doesn't display.

我的项目布局是这样的：

My item layout look like this:

 <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="5dp" >

    <com.android.volley.toolbox.NetworkImageView
        android:id="@+id/imgNewsItem"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:scaleType="fitXY"
        android:src="@drawable/news_default_image"
      android:visibility="gone" />

    <ProgressBar
        android:id="@+id/progressNewsList"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center" 
        >
    </ProgressBar>
</LinearLayout>

此示例中的ImageCacheManager： https://github.com/rdrobinson3/VolleyImageCacheExample
你能告诉我在哪里，我错了？先谢谢了。

The ImageCacheManager from this example: https://github.com/rdrobinson3/VolleyImageCacheExample Could you please tell me where I am wrong?. Thanks in advance.

更新：另外，进度条没有下载时显示

Update: another, the progress bar isn't showed when downloading.

推荐答案

您需要更改ImageListener.onResponse方法如下：

You need to change ImageListener.onResponse method to the following:

@Override
public void onResponse(ImageContainer response, boolean isImmediate) {
    Bitmap bitmap = response.getBitmap();
    if(bitmap != null){
       progressNewsList.setVisibility(View.GONE);
       imgNewsItem.setVisibility(View.VISIBLE);
       imgNewsItem.setImageBitmap(bitmap);
   }
}

以下是该ImageListener java的文档：

The following is the java doc for the ImageListener:

界面图像请求的响应处理程序。该呼叫流程
  是这样的：1。在被连接到一个请求，onResponse（响应，
  真）将被调用，以反映已经是所有缓存数据
  可用。如果数据可用，r​​esponse.getBitmap（）会
  非空。 2.一个网络响应返回之后，只有一个
  以下情况下会发生： - onResponse（响应，FALSE）将
  如果图像被加载调用。或者 - onErrorResponse将被称为如果
  有一个错误加载图像

Interface for the response handlers on image requests. The call flow is this: 1. Upon being attached to a request, onResponse(response, true) will be invoked to reflect any cached data that was already available. If the data was available, response.getBitmap() will be non-null. 2. After a network response returns, only one of the following cases will happen: - onResponse(response, false) will be called if the image was loaded. or - onErrorResponse will be called if there was an error loading the image

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