Listview使用通用图像加载器重新加载已加载的图像

Question

在我的Android项目我显示所有图像web service(Url),以ListView用于这个目的,我已经使用Universal image loader.如果我向下滚动然后向上滚动,则在List中加载一些图像后,已经加载的图像将再次重新加载.

 DisplayImageOptions.Builder displayImageOptionsBuilder = new DisplayImageOptions
                    .Builder().cacheOnDisk(true).cacheInMemory(true).considerExifParams(true);


 ImageLoader.getInstance().displayImage(imageUri, imageView,
                  displayImageOptionsBuilder.build());

我尝试了什么

ImageAware imageAware = new ImageViewAware(imageView, false);
            ImageLoader.getInstance().displayImage(imageUri, imageAware,displayImageOptionsBuilder.build());

即使使用此代码,它也不会在ListView中进行任何更改 reloading

编辑

适配器类

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final String name = getItem(position);
        View view = convertView;    

        if (view == null) {
            view = createView();
            ViewHolder viewHolder = new ViewHolder();    
            viewHolder.image = (ImageView) view.findViewById(R.id.capsule_media_list_item_thumbnail_1);             
            view.setTag(viewHolder);    
        }

ImageHelper.initImage(viewHolder.image,
                imageUrl,
                R.drawable.vx_loading, loadingImageResource,displayOptionsCustomizer);

return view;
}

 private final DisplayOptionsCustomizer displayOptionsCustomizer = new DisplayOptionsCustomizer() {

        @Override
        public void customizeImageOptions(DisplayImageOptions.Builder displayImageOptionsBuilder) {
            displayImageOptionsBuilder.displayer(new RoundedBitmapDisplayer(ApplicationUtils
                    .dipToPixelsRounded(6, getContext()), 0));
        }
    };    

static class ViewHolder {
        public ImageView image;

    }

ImageHelper.java

public static void initImage(final ImageView imageView, final String imageUri,
                                 final int noImageResource, final int loadingImageResource,
                                 final DisplayOptionsCustomizer displayOptionsCustomizer) {
        if (StringUtils.isNotBlank(imageUri)) {             

            DisplayImageOptions.Builder displayImageOptionsBuilder = new DisplayImageOptions
                    .Builder().cacheOnDisk(true).cacheInMemory(true).considerExifParams(true);
            displayImageOptionsBuilder.showImageOnLoading(loadingImageResource)
                    .showImageOnFail(noImageResource);
            if (displayOptionsCustomizer != null) {
                displayOptionsCustomizer.customizeImageOptions(displayImageOptionsBuilder);
            }


           ImageLoader.getInstance().displayImage(imageUri, imageView,
                   displayImageOptionsBuilder.build());
        } else {
            if (noImageResource != 0) {
                imageView.setImageResource(noImageResource);
            } else {
                imageView.setVisibility(View.GONE);
            }
        }
    }

根据 答案编辑适配器类Dhir Pratap

public class ImagesListAdapter extends ArrayAdapter<String> {

private List imagesList = new ArrayList<String>();
private Context context;
ImageLoader imageLoader;
DisplayImageOptions options;

public ImagesListAdapter(Context context, List<String> imagesList) {
        super(context, -1,imagesList);
        this.imagesList = imagesList;
        this.context = context;
imageLoader = ImageLoader.getInstance();
 options = new DisplayImageOptions.Builder().cacheInMemory(true)
        .cacheOnDisk(true).resetViewBeforeLoading(true)
        .showImageForEmptyUri(fallbackImage)
        .showImageOnFail(fallbackImage)
        .showImageOnLoading(fallbackImage).build();

    }    

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final String name = getItem(position);
        View view = convertView;    
 ViewHolder viewHolder;

        if (view == null) {
            view = createView();
            viewHolder = new ViewHolder();    
            viewHolder.image = (ImageView) view.findViewById(R.id.capsule_media_list_item_thumbnail_1);             
            view.setTag(viewHolder);    
        }
else{

viewHolder =  (ViewHolder) view.getTag(viewHolder); 
}

/*ImageHelper.initImage(viewHolder.image,
                imageUrl,
             R.drawable.vx_loading, loadingImageResource,displayOptionsCustomizer);*/

imageLoader.displayImage(imageUrl,viewHolder.image,
           options);

return view;
}

/* private final DisplayOptionsCustomizer displayOptionsCustomizer = new DisplayOptionsCustomizer() {

        @Override
        public void customizeImageOptions(DisplayImageOptions.Builder displayImageOptionsBuilder) {
            displayImageOptionsBuilder.displayer(new RoundedBitmapDisplayer(ApplicationUtils
                    .dipToPixelsRounded(6, getContext()), 0));
        }
    };   */ 

static class ViewHolder {
        public ImageView image;

    }

}

Answer 1

你可以做很少的修复

1. 你的观看者几乎没用.您必须按照以下方式使用它

   ViewHolder viewHolder;
   if (view == null) {
       viewHolder = new ViewHolder();    
       viewHolder.image = (ImageView) view.findViewById(R.id.capsule_media_list_item_thumbnail_1);             
       view.setTag(viewHolder);    
   }else{
    viewHolder =  view.getTag(viewHolder); 
   }
   

2. 您应该只声​​明ImageLoader和DisplayImageOptions实例一次.可能在构造函数中.

   ImageLoader imageLoader = ImageLoader.getInstance();
   DisplayImageOptions options = new DisplayImageOptions.Builder().cacheInMemory(true)
           .cacheOnDisc(true).resetViewBeforeLoading(true)
           .showImageForEmptyUri(fallbackImage)
           .showImageOnFail(fallbackImage)
           .showImageOnLoading(fallbackImage).build();
   

3. 在获取视图中,您只需加载图像,如下所示

编辑: 我没有使用过ImageAware.你必须这样使用.

ImageAware imageAware = new ImageViewAware(viewHolder.image, false);
imageLoader.displayImage(imageUri, imageAware,options);

这里的答案说这确实是UIL的一个问题,在1.9版本中得到了解决.

编辑2: 我在Github上跟踪了有关该问题的讨论,发现这个答案可以手动检查图像网址.它建议做以下事情

//lets prevent "blinking" by "saving URL tag" hack

    if (viewHolder.image.getTag() == null ||
            !viewHolder.image.getTag().equals(imageUri)) {

        //we only load image if prev. URL and current URL do not match, or tag is null

        ImageAware imageAware = new ImageViewAware(viewHolder.image, false);
        imageLoader.displayImage(imageUri, imageAware,options);
        viewHolder.image.setTag(imageUri);
    }