I have an app where I take data from API (some points on map with properties like descriptions, lan, lat, and list of photos) because of offline mode. I am not sure if I should use sharedPreferences or some okHttp cache (or some ORM database). SharedPref is good for small values, not for list of objects. Do you have suggestions/best practices?
Thanks
Store your data in db with image URIs. Store Images in memory cache and retrieve them from their URI. Retrofit doesn't comes with support for image loading from network by itself. If you don't want to go into depth of all this, you can use Glide or Picasso.
Picasso saves full image and can be resized at the time of loading. Glide caches images after resizing. See what fits your case.
Storing and retreiving images directly from database will require too much processing and slow down loading of images especially if you need large images. For more information read check out developers note on Caching Bitmaps and Display Bitmaps Efficiently.
I would suggest you to use response cache if you require the response only to display. Retrofit provides a nice and handy response caching method, you can make use of Interceptors to cache response. hope you are using retrofit latest version 2.1.0. check out this link to get more.
If you wanted to perform some operations like marking favourites etc. you can go for database.
Related
I want to save the images fetched from server for once and from next time i want to check first whether images are stored or not in device, if not then again it should fetch from server and store in user's device again, and if yes then application will use images directly rather than fetching from server again and again. It will be useful for enhancing the speed of application. Basically my application is fetching multiple images from server so i want to save those images on user's android device and from next time application should fetch from device. I think you got my question.
The simple way:
You can use Picasso.
It is a simple lib which provides image downloading and caching.
In my opinion it might not be the fastest, but it is pretty simple and intuitive. It does its job well and none who I asked complained about it.
Picasso
Other libs:
UIL
Volley
Glide
fresco
To make it short. There are lots of other libs. An awesome comparision of the most Populat ones can be found here and here
The do it yourself way:
You can also write you own caching logic with a LRUCache. Which is also pretty simple.
Take a look at:
https://developer.android.com/topic/performance/graphics/cache-bitmap.html
The LRUCache is just a Memory Cache so you might also want to use a DiskLRUCache
So i´m creating a app in Android which stores images in a external server. I want to know where is better to make the optimization of the image file, in server, or give the non-optimize image to local and then optimize inside the app. Im using mysql for store the images, but if its better to use sqlite server i will change it. Thanks.
The best thing to do here is create an application on your server exposed through an API with query parameters to specify image sizes + caching mechanism.
For example:
www.mywebsite.com/imageloader/file-identifier?width=50&height=50&format=png
then implement a caching mechanism take a look at (https://dev.mysql.com/doc/refman/5.1/en/ha-memcached.html) for mysql on the server for this image using these parameters so the application can quickly return this file each time and not require too much work from the application. This will allow you to request multiple images at specific sizes when you need them for example only as a thumbnail... Or a full Gallery image which can be something much larger.
Additionally you will want to use an Image Library and there are certainly quite a few for Android (to name a few):
Picasso from Square http://square.github.io/picasso/
Fresco from Facebook https://github.com/facebook/fresco
Ion from this Github https://github.com/koush/ion
These can all help you format your images and cache them locally and even downsize the images as necessary.
I have an Android application that would retrieve data (images+text) from a php remote server and display them in a GridView.
I am doing the operation in the background using Loaders. I have separate connections for images and texts since retrieving images would take longer and I want to display the texts immediately. The texts are encoded with Json on the server after being retrieved from MySQL. On the app, I am parsing the Json Objects and displaying the texts as I need.
The problem is with images. I am not sure if encoding the images with Json would be a good idea. Also the images are saved as blob in the database, in order to encode them with Json I need to use base64_encode() before which is not efficient. I have seen many posts about this, but it’s always a simple example when you have to get one image. In my case I’ll be retrieving up to 30 small-size images.
My question is, I can proceed with what I just presented, but it seems that there should be a better way to do this. What do you think about this? Am I going the wrong way?
Also I was thinking if I can display each image separately in the gridview once it is ready (not waiting for all the images to be ready) just like in the “Google Play App”’s GridView. What approach can I take to achieve this?
Thanks in advance folks!
Best approach in my eyes would be to download the image files as normal image files via a HTTP get request. Make sure it is threaded of course, and have a thread pool that you can queue up requests into, and have 2-3 threads go through and download.
In terms of saving them, I would personally move away from saving to blob in a database, and opt to save them to the persisted storage in your application's private directory. Saving the image files with their filename as their id in the database you have created will be much quicker for loading them back in.
You can also hold a reference to the ImageView, and have it display a place-holder initially, with a successful HTTP request replacing the bitmap of the ImageView with the one you have just downloaded/read in from storage.
You can also do some image caching within the HTTP request you make.
ImageView myImageView = findViewById(R.id.testImage);
URL url = new URL("http://www.website.com/image.jpg");
URLConnection connection = url.openConnection();
connection.setUseCaches(true);
Object response = connection.getContent();
if (response instanceof Bitmap) {
Bitmap bitmap = (Bitmap)response;
myImageView.setBitmap(bitmap);
}
It also may be helpful to lookup the uses of the LRUCache, which performs a lot of caching functionality for you.
Check out this link at the Android Developer site for a good in depth guide to image caching
Edit:
You can use the advice in Robert Rowntree's answer to load bitmaps more efficiently to cut down on your memory use as well. The link provided details loading of bitmaps using less memory, something that would work well if you are creating thumbnails from larger images downloaded over the web and saved off to local storage.
IMO - there are 2 issues , moving the images across the network to the client and getting them loaded.
Assuming that you are using http as the protocol, you should have a multithreaded solution for http as is available in apache httpclient package. That will get the pictures to the phone fast.
Then , you have to present the pics by getting them into memory and a cache. Here you can consider what 'gallery3D' app does with its grid and bitmaps but its pretty complicated to read thru that code.
check out - http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
check out code samples for loading thumbs from bitmaps.
I'm a bit confused about how to cache data in Android. I've seen many people implementing their own cache (eg, in droidfu project), but Android seems to have its own caching system with ResponseCache.
Is there any reason for not using Android cache?
What's the standard way to cache URLConnection response (text, data, json...), and where can I found examples?
Thanks
You have no control over the size of the cache or when objects get cleared (to my knowledge)
You cannot set the cache to the SD card
For small web-service requests the ResponseCache will suffice, and is the standard way of caching the raw response. It is only really when dealing with larger objects that you will need your own cache.
Alternatively you could
Serialize the data and save it to a local file
For basic data you could save it in SharedPreferences if it is long-lived
I want to know the best way to store images from and api into room db. I'm making a sport application where I receive data and images from an api. When I'm in online mode, the images are loaded using the urls provided by the api but when offline, images should be stored and retrieved from the database in offline mode. I want to know how to convert that url of image to an image and load it in offline mode.
PS : more than 100 images will be saved, does room db fit with that? Thank you.
store your image in cache using picasso
first add this to your gradle.
implementation 'com.squareup.picasso:picasso:2.71828'
then you can call the image from your url and store it in your cache.
Picasso.get().load(YOUR_IMAGE_URL).error(R.drawable.error_img).placeholder(R.drawable.loading_image).into(YOUR_IMAGEVIEW);
Picasso will only download the image once, and if you call the same url again it will be redirected to your cache instead of downloading it again(more or less).
note: check the profilier to see the data consumption.
To continue with L2_Paver's answer.
You can also check Glide for the same purpose. You might want to consider the pros and cons of each libraries which serves well for your purpose. This answer might give you some more insights about the comparison.
Picasso v/s Imageloader v/s Fresco vs Glide