有没有办法强迫Volley刷新图像？

Question

我目前正在开发一个前端应用程序,该应用程序严重依赖从Web服务下载的映像.为了简短起见,前端从我们的webservice下载一个具有3个图像插槽的给定用户配置文件.如果这样的用户上传了一张新图片(保持相同的网址),那么在我杀死我的应用程序之前它不会刷新,所以如果我将它放在后台并恢复数据将不会被更改.

以下是处理ImageNetworkView的代码示例:

mImage = (NetworkImageView) mView
            .findViewById(R.id.profile_network_image);

    mProgressBar = (ProgressBar) mView
            .findViewById(R.id.profileProgressBar);

    // Cargo image loader
    mLoader = VolleySingleton.getInstance(mActivity).getImageLoader();

    if(mLoader!=null && imageUrl!=null){
        mLoader.get(imageUrl, new ImageListener() {


            @Override
            public void onErrorResponse(VolleyError error) {

                System.out.println("Error loading "+imageUrl+"...");

            }

            @Override
            public void onResponse(ImageContainer response, boolean isImmediate) {
                if (response.getBitmap() != null) {
                    mImage.setImageBitmap(response.getBitmap());
                    mProgressBar.setVisibility(View.GONE);
                    System.out.println("Done loading "+imageUrl);
                }

            }
        });

mImage.setImageUrl(imageUrl, mLoader);

这是我的VolleySingleton和Cache类:

public class VolleySingleton {
private static VolleySingleton mInstance = null;
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private ImageLoader.ImageCache mImageCache;

private VolleySingleton(Context context){
    mRequestQueue = Volley.newRequestQueue(context);
    mImageCache = new BitmapLruImageCache();
    mImageLoader = new ImageLoader(this.mRequestQueue, mImageCache);
}

public static VolleySingleton getInstance(Context context){
    if(mInstance == null){
        mInstance = new VolleySingleton(context);
    }
    return mInstance;
}

public RequestQueue getRequestQueue(){
    return this.mRequestQueue;
}

public ImageLoader getImageLoader(){
    return this.mImageLoader;
}

public ImageLoader.ImageCache getImageCache(){
    return mImageCache;
}

缓存类:

public class BitmapLruImageCache extends LruCache<String, Bitmap> implements ImageCache {

public static int getDefaultLruCacheSize() {
    final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
    final int cacheSize = maxMemory / 8;

    return cacheSize;
}

public BitmapLruImageCache() {
    this(getDefaultLruCacheSize());

    Log.v("tag", Integer.toString(getDefaultLruCacheSize()));
}

public BitmapLruImageCache(int sizeInKiloBytes) {
    super(sizeInKiloBytes);

}

@Override
protected int sizeOf(String key, Bitmap value) {
    return value.getRowBytes() * value.getHeight() / 1024;
}

@Override
public Bitmap getBitmap(String url) {
    return get(url);
}

@Override
public void putBitmap(String url, Bitmap bitmap) {
    put(url, bitmap);
}

谢谢大家!

编辑:我一直在努力找到一个解决方法,到目前为止我想出了这个:

如果我在调用getBitmap(url)时将新图像放在分配给图像URL的缓存中,我将获得新图像,但问题仍然存在,如果我使用后退按钮关闭应用程序并打开它一次更多的凌空加载旧图像,但如果我杀了应用程序,它将加载新的...这是我用来将图像放在缓存上的代码:

VolleySingleton.getInstance(mActivity).getImageCache().putBitmap(imageUrl, bmp);

tempBitmap = VolleySingleton.getInstance(mActivity).getImageCache().getBitmap(imageUrl);

Answer 1

问题是图像缓存位于内存中，ImageLoader在调用之前会检查它。

        // Try to look up the request in the cache of remote images.
    Bitmap cachedBitmap = mCache.getBitmap(cacheKey);
    if (cachedBitmap != null) {
        // Return the cached bitmap.
        ImageContainer container = new ImageContainer(cachedBitmap, requestUrl, null, null);
        imageListener.onResponse(container, true);
        return container;
    }

您需要通过以下方式手动清理缓存：

VolleySingleton.getInstance(mActivity).getImageCache().remove(imageUrl);

或者

VolleySingleton.getInstance(mActivity).getImageCache().evictAll()