Develop Reference

Caching Images and strings using Retrofit, okhttp, picasso

I am working on an app with a lot of dynamic and changing content.
I pull all my data from my server when the app is loading.
As a result, nearly every activity/fragment is loading separately which will cause the user to wait a lot of time for each "page" to load individually.
My goal is to create one loading page when the app starts while being responssible for all the downloading and will disk cache all the images and info(strings) and ti pull them at the right time. (or at least to most of it)
I had the chance to use retrofit, okhttp and Picasso as a single additional library, I know though that they can work together and to be synced and that disk cacheing is available through at least two of this libraries (picasso and okhttp) I'm not sure though which one should do which part and how I can sync them together.
I will appreciate every Tip/Guidance, thanks ahead.

okhttp provides support for cache control headers. I've implemented them in an app before to provide a cache when network is flaky using this guide like so:
int cacheSize = 10 * 1024 * 1024; // 10 MiB
Cache cache = new Cache(cacheDirectory, cacheSize);
client = new OkHttpClient.Builder()
.cache(cache)
.build();
As Retrofit uses okhttp internally (if you're using the latest at least), you don't configure any caching for it. Just use the okhttp client you just configured:
RestAdapter restAdapter = new RestAdapter.Builder()
.setClient(new OkClient(client))
.setServer("http://example.com")
...
.build();
Picasso automatically caches images using some default cache size limit. You can change Picasso's default, and I've found some answers here and here. You could set the cache size in the onCreate of your application:
Picasso.Builder builder = new Picasso.Builder(this);
builder.downloader(new OkHttpDownloader(this,Integer.MAX_VALUE));
Picasso picasso = builder.build();
picasso.setIndicatorsEnabled(true);
picasso.setLoggingEnabled(true);
Picasso.setSingletonInstance(picasso);
Picasso also lets you prefetch images earlier on in an app's lifecycle if you have the time to begin with (say, on a loading screen) and want to make later parts of the app load quicker. To do that, I would use the fetch method from the Picasso builder to get the images, but not insert them into any ImageViews. You can Google it too, but there's a quick answer here which explains the background behind this:
Picasso.with(getApplicationContext())
.load(url)
.fetch();
IIRC you need to make sure you fetch the same sized and transformed image as you try and retrieve later, because Picasso caches the transformed image result rather than the raw downloaded image.

Glide : How to find if the image is already cached and use the cached version?

Scenario:
I have a large GIF image which I want to cache the first time user opens the app using Glide - Image Loading and Caching library. After that whenever user opens the app, I want to show the cached version if present. This GIF URL will expire after a given interval. When it expires, I fetch the new GIF URL and display/cache that for future use.
What I tried:
I went through Caching and Cache Invalidation on Glide's github page. I also went though the Google Group thread Ensuring That Images Loaded Only Come From Disk Cache, which shows how to get the image form cache. I also went through How to invalidate Glide cache for some specific images question.
From the links above I see the following code sniplet which shows how to load the image from cache. However this only tries to get the image from cache. If its not present in cache, it doesn't try to get from the network and fails:
Glide.with(TheActivity.this)
.using(new StreamModelLoader<String>() {
#Override
public DataFetcher<InputStream> getResourceFetcher(final String model, int i, int i1) {
return new DataFetcher<InputStream>() {
#Override
public InputStream loadData(Priority priority) throws Exception {
throw new IOException();
}
#Override
public void cleanup() {
}
#Override
public String getId() {
return model;
}
#Override
public void cancel() {
}
};
}
})
.load("http://sampleurl.com/sample.gif")
.diskCacheStrategy(DiskCacheStrategy.SOURCE)
.into(theImageView);
Questions:
Is there a cleaner way to achieve the following: Show the GIF image from the cache if present else download the GIF, cache it for later use and show it in the ImageView.
The caching article above mentions the following:
In practice, the best way to invalidate a cache file is to change
your identifier when the content changes (url, uri, file path etc)
The server sends a different URL to the app when the previous one expires. In this case, I believe the old image will eventually be Garbage Collected? Is there a way to force remove the image from the cache?
On a similar note, is there a way to prevent the Garbage Collection of an image with specific key (to prevent downloading the large file again) and then later instruct to delete the old image from cache when the URL changes?

You don't need a custom ModelLoader to show the GIF from cache if present and fetch it otherwise, that's actually Glide's default behavior. Just using a standard load line should work fine:
Glide.with(TheActivity.this)
.load("http://sampleurl.com/sample.gif")
.diskCacheStrategy(DiskCacheStrategy.SOURCE)
.into(theImageView);
Your code will prevent Glide from downloading the GIF and will only show the GIF if it is already cached, which it sounds like you don't want.
Yes, the old image will eventually be removed. By default Glide uses an LRU cache, so when the cache is full, the least recently used image will be removed. You can easily customize the size of the cache to help this along if you want. See the Configuration wiki page for how to change the cache size.
Unfortunately there isn't any way to influence the contents of the cache directly. You cannot either remove an item explicitly, or force one to be kept. In practice with an appropriate disk cache size you usually don't need to worry about doing either. If you display your image often enough, it won't be evicted. If you try to cache additional items and run out of space in the cache, older items will be evicted automatically to make space.

Glide.with(context)
.load("http://sampleurl.com/sample.gif")
.skipMemoryCache(true)
.into(imageView);
You already noticed that we called .skipMemoryCache(true) to specifically tell Glide to skip the memory cache. This means that Glide will not put the image in the memory cache. It's important to understand, that this only affects the memory cache! Glide will still utilize the disk cache to avoid another network request for the next request to the same image URL.for more read this
Glide Cache & request optimization.
Happy coding!!

Android Image invalidate in fresco

I am migrating android image caching library from picasso to fresco. I want to know if there is any way to invalidate image already catched as I am adding feature to replace existing image there is way to do so in picasso like
Picasso.with(context).invalidate(URI);
This line remove the cached image and use new one using the url provided which is same like,
http://example.com/image_path
In fresco I have tried using
Fresco.getImagePipeline().evictFromMemoryCache(uri);
This is removing image from view but adding same old cached image again and not getting new one from network as it is working in picasso.
Please refer question Invalidate cache in Picasso The accepted answer doing great in case of picasso.

Fresco.getImagePipeline().evictFromMemoryCache(uri);
Above code line remove the image from the catche but image remains there in the disk and render same if called. We need to remove same image from disk as well. Bellow two lines remove the the image from disc cache also we need to remove the small that is thumbnail image if saved from disk cache.
Fresco.getImagePipelineFactory().getMainDiskStorageCache().remove(new SimpleCacheKey(uri.toString()));
Fresco.getImagePipelineFactory().getSmallImageDiskStorageCache().remove(new SimpleCacheKey(uri.toString()));
Note: if you are using custom cache key you need to change it that way.

Try this
public static void clearCache(){
//
ImagePipeline imagePipeline = com.facebook.drawee.backends.pipeline.Fresco.getImagePipeline();
imagePipeline.clearMemoryCaches();
imagePipeline.clearDiskCaches();
// combines above two lines
imagePipeline.clearCaches();
}

Picasso: Loading cached image from disk too much slow

So, I was starting my project and wants to use Picasso in my project because its popular and used by many projects out there.
I included picasso using gradle and tried loading facebook profile url with this. http://graph.facebook.com/rohitiskul/picture.
It worked very well. It loaded image from network without any issues. I restarted the app.(Without actually killing the process). It showed me the same image instantly cached in Memory.
But then, I killed the app (force stop) and restarted. It took almost 10+ seconds to load the image. And that image was loading from the disk when I checked in the debug logs.
My code looks like this -
In MainActivity-
Picasso.with(context)
.load("http://graph.facebook.com/rohitiskul/picture")
.into(imageView);
In application class-
Picasso picasso = new Picasso.Builder(this)
.indicatorsEnabled(true).loggingEnabled(true).build()
Picasso.setSingletonInstance(picasso);
Anyone with the similar problem? Any solution would be helpful.
I tried loading same Url with UniversalImageLoader and it was fast when fetching cached image from disk.
Edit
Earlier while playing with my app, I found out that Picasso wasn't loading the disk cached image when device was offline.

I encounter the same problem,
but find only slow for the first image, later images will be fast.
Probably it needs a warm-up (loading index cache) ?

Okay i got your problem. I have fixed it by doing this
Picasso.with(context)
.load("http://graph.facebook.com/rohitiskul/picture")
.networkPolicy(NetworkPolicy.OFFLINE)
.into(imageView, new Callback() {
#Override
public void onSuccess() { }
#Override
public void onError() {
// Try again online if cache failed
Picasso.with(context)
.load("http://graph.facebook.com/rohitiskul/picture")
.into(imageView);
}
});
Explanation:
Picasso will look for images in cache.
If it failed only then image will be downloaded over network. In your case from facebook.

This issue I had also faced earlier, with this what I understood that Picasso refer the cached image based on image name mentioned in the URL.
In your case you don't have image name in URL like 'image1.jpg'. Due to which Picasso is finding it difficult to read from cache and it downloads the image everytime
You can give a try to image containing the image name in URL and that will work

Picasso doesn't offer disk cache out of the box. Instead, it relies on an Http Cache.
Make sure you add OkHttp to your dependency list.

Add a string identifier with the stableKey method when making the request so Picasso can identify your requests and quickly load it from the cache.
Example:
Picasso.Builder(context).loggingEnabled(true).build()
.load(imageUrl)
.stableKey("myImage")
.into(imageView)

(Glide) Getting image from cache if it exists

I have trouble when I'm using Glide in my app. As I've understood, if image was downloaded once and I request image from cache from other activity, Glide must show image quick. And I got this behavior, but not in my app. Image loads very slow (about 3 seconds), although in another app it was about 0.4 second.
My code with calling Glide:
Glide.with(this)
.load(url)
.signature(new StringSignature(url))
.diskCacheStrategy(DiskCacheStrategy.ALL)
.into(mHeader);
And in other activity code are same.
May you help me?
Thanks

You don't need the signature(url) part, the model (url String in your case) is already a part of the cache key.
The problem may be that your header changes size. The view size (= resulting Bitmap size) needs to be constant for a cache hit. However since you're doing ALL caching the load should still be fast. Is there anything changing in the url maybe, like a sessionid or similar? That would make the cache miss.
If the url you're loading is an animated GIF RESULT caching can be the culprit, here's a reference.