How to cache images using dynamic image URIs?

Question

How can I setup the Android Universal Image Loader to load dynamic image URIs?

For instance:

Both URIs must be representing the same remote image image.jpg:

• https://sample.com/image.jpg?querystring=1
• https://sample.com/image.jpg?querystring=2
• and so on...

Reference:

Sometime, you may not want to use the image URL as cache key because part of the URL is dynamic (i.e.: for access control purpose)

SDWebImage - Using cache key filter

I am using the SDWebImage inside my iOS application and I really need a similar feature to be able to use the UIL inside its Android version.

Answer 1

I think you can use this memory cache decorator:

public class CustomMemoryCache implements MemoryCacheAware<String, Bitmap> {

    private final MemoryCacheAware<String, Bitmap> cache;

    public CustomMemoryCache(MemoryCacheAware<String, Bitmap> cache) {
        this.cache = cache;
    }

    @Override
    public boolean put(String key, Bitmap value) {
        return cache.put(cleanKey(key), value);
    }

    @Override
    public Bitmap get(String key) {
        return cache.get(cleanKey(key));
    }

    @Override
    public void remove(String key) {
        cache.remove(cleanKey(key));
    }

    @Override
    public Collection<String> keys() {
        return cache.keys();
    }

    @Override
    public void clear() {
        cache.clear();
    }

    private String cleanKey(String key) {
        return key.substring(0, key.lastIndexOf("?")) + 
                 key.substring(key.lastIndexOf("_")); 
            // original cache key is like "[imageUri]_[width]x[height]"
    }
}

Then wrap any ready memory cache implementation and set it into the configuration. For example:

LruMemoryCache memoryCache = new LruMemoryCache(memoryCacheSize);
CustomMemoryCache memoryCacheDecorator = new CustomMemoryCache(memoryCache);

ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(context)
    ...
    .memoryCache(memoryCacheDecorator)
    ...
    .build();