I'm new to caching and stuff. I have an app that fetches images from firebase storage by their url using Glide. Now it will cost me a lot if the user fetches a single image "every time" they use the app using the url (also a single image might be visible in couple of activities , so then fetching becomes redundant). So does glide cache is valid even after app restart and across all the activities or is it activity related( I mean for every activity does it has separate cache or is it just simply dependent on the url)?
Also is the caching enabled by default?
Sorry if the question sounds stupid, but otherwise the cost will increase significantly. Thanks.
Yes it's store some cache after app restart also the best way to invalidate a cache file is to change your identifier when the content changes (url, uri, file path etc) when possible.
Related
My app uses images from a URL and I want to reduce resources usage for both server and client.
I wonder if the Android SDK already offers something for this (if there's some standard way to do it) or I just have to figure it out.
What I have in mind is:
download images on local storage (external or internal) when accessing content (lazy loading, progress bar) and keeping them there for next use
update images (download and replace) if changed on server (keep checksum in a database that is queried when the application is started)
in order to avoid excessive local disk usage (they are quite big), delete images for content that has not been accessed for N days. This is done while loading the app or in a background asynchronous service
Should I do this step by step or is there something that already takes care of it. Are there libraries to do this properly?
I think Picasso library is best for this, it has many capabilities and is really easy to use, its features include smooth image caching (the features you need), image processing and Async downloading from URL too. It has so many useful features.
Here is its url link
http://square.github.io/picasso/
I am trying to figure out the best and the most efficient way of caching images to the disk, such that they would persist even after app is killed and re-launched in airplane mode. Consider the following use case:
Open the app and get all images and display them in their respective ImageView's
Kill the app
Put device in air plane mode
Open the app again.
I am trying to get the images to persist in an offline cache so that they can be displayed in the scenario mentioned above.
I went through documentation for picasso and glide and it wasn't exactly clear if their disk caching would work in this case.
Is there a way to do this using picasso or glide? I am trying to avoid having to write a custom implementation for storing this in SQLite etc.
Glide will do this for you by default without any extra work on your side. You can also customize what versions of the requested image to store in the cache.
One important thing you need to consider is if the URLs that you use Glide to fetch images from are available offline otherwise you will need to have some way to cache those as well so that you can initiate the Glide calls when you are offline.
You can see how I did it in this project: https://github.com/KhalafMH/popular-movies-android.git
To read about how to configure Glide caching see:
http://bumptech.github.io/glide/doc/caching.html
I am building an android application which requires displaying images as a flip-view which will be retrieved from server. I have considered two approaches
Retrieving images from server URL and then displaying OR
Storing the image in db at server(MySQL) and then retrieving it from sq-lite on android application
My question is, which approach will be better considering everything (performance, etc.)?
Any other better approach is also welcome :)
This depends upon your Application and products you are going to display using Images, If they are not updated frequently then it would be better to use caching for faster user experience but if data is regulatory updated and previous data is keep getting filtered then always load using network.
Another approach you can just store latest 10-20 entries in your Database and as soon as you opens the application he can see some data and new data gets downloaded, this approach keeps users engage don't leave them your app just because every time they see loading.
For Image caching purposes there various good libraries avaible which are stable solutions for multiple images downloading as well as caching purposes E.g.
UniversalImageLoader, picasso, Volley
A good approach could be store locally images locally on demand, and keep it on cache, if the image changes on future you can invalidate your cache and download a new image.
I have used in a project a library that helps me a lot with to download the image in background, allows you also load image from cache automatically if stored previously or invalidate the cache. The library is android-query and here is an example of how you could use it.
You store images locally and load then to your app from local storage (This happens in a background thread)
You update the local storage by fetching the images in background, when needed, and then trigger the load from local storage (This also happens in a background thread)
This way you won get ANR's (application not responding) because of slow or missing internet connection, and you will be able to show images without connection at all.
I'm making an android app, here the images are getting from Cloud, is it good idea to download images and save it & use it further. Or download images every-time user uses the app, what idea you prefer is the best?
Because downloading images always is slow & its bad i know but at some point if the images are updated then how to get to know about it?
You should definitely cache your downloaded files!
Do it in your internal app directory where only you do have access to (or otherwise external storage, thats still ok).
Bandwidth and connections are always expensive and should kept low as much as possible.
So your user can see images fast even on a bad connection and your app doesn't waste his valuable bandwidth of a users data plan.
Maybe this could also help you:
https://github.com/novoda/ImageLoader
http://www.androidhive.info/2012/07/android-loading-image-from-url-http/
Make it easy on yourself and use something like Android Smart Image View. It takes care of loading and caching, and it's just about a drop-in replacement for Android's ImageView. Universal Image Loader is another alternative, more configurable, but not as quick to implement.
I used https://github.com/nostra13/Android-Universal-Image-Loader
but I think you not want only download and cache.
these no trick ,if you want check weather the image update or not, you can add metadata for image, just like md5 .
in html and browser, you can set expires header for a image:
enter link description here
but in android app, you control all yourself.
Downloading images and saving them is probably the best way to do it because you don't want to download the same images over and over. If the images are updated you can delete the older one and download the new ones. Just make sure you don't download/save a million images. Take a look at this library. It has a built-in cache on sdcard/external sd.
Downloading images from the net for display, with possible requirement of caching is a very common problem that many people have solved, you can try these solutions to see which fits you:
Ion (https://github.com/koush/ion) - very flexible and feature complete, plus it can download more than images but JSON, Strings, Files, and Java types as well. The part that I really like about this is that it can automatically cancel operations when the calling Activity finishes, so users don't waste time & bandwidth downloading images that will no longer be displayed
Universal Image Loader (https://github.com/nostra13/Android-Universal-Image-Loader) - equally capable for most use cases but for downloading/caching images only
I am building the application that will load list of news from the website. Each news/headline has an image. I want to save/cash the images so user does not has to download them again.
Q: In your opinion, what would be a better/more sufficient way: Loading images and saving them on the device or use the CacheManager? At the moment I am using the first solution and everything works fine. However, the website has many categories and even more news per category therefore there are lot of images saved on the device. Is it normal in this type of applications to save the images on the device?
Thanks for your help,
marqs
I don't think you should save the images on the device, because of many reasons:
Why wasting the device space on news images? All the user wants is to read the news and thats it. (In your case maybe open it later, but still - not forever)
You can save it on the device and make the app. delete those files after lets say 24 hours..
The main issue is the privacy issue, when the user is deleting the cache files he thinks all the webs he visited has wiped from the device, but in this case they aren't..
Maybe you can just add a "Clean Cache" button in the app. but after all I wrote I think using the Cache-manager is the best way - just because it was meant for those things exactly..
:)
Rotem
I didn't find a reason to use CacheManager. I used getCacheDir and stored everything on file. I have two levels of cache. First when I fetch it, I store in memory and disk. When in memory gets bigger than 30 objects, I started clearing the memory to make some room for the new images coming. However, I still keep the images around on disk and bring in to memory as needed. I found this to give me the smoothest scrolling. After about an hour, I start expiring the image on disk too.