The AsyncTask for downloading the image is defined, but we need to execute it in order to run that AsyncTask. To do so, write this line in your onCreate method in your Activity class, or in an onClick method of a button or other places you see fit.
After the image is downloaded, we need a way to load the image bitmap from the internal storage, so we can use it.
This method takes two paramethers, a context and an image file name, without the full path, the context. Now we have everything we needed for setting the image of an ImageView or any other Views that you like to use the image on. Article Summary. This will produce a pop-up window with a list of options. Select Start a new Android Studio project. If you are starting a new project: Start by selecting a device type by clicking on one of the tabs at the top of the pop-up window, and by selecting an activity type.
Click Next to continue. Name your project, choose a programming language, and the minimum API level required. Click on the name of the project on the far left-hand side of the window. Click on the drawable folder. The desired folder will be drawable within the res folder. Drag the image file to the drawable folder in Android Studio. This will produce a pop-menu titled Move.
You can also copy and paste the image file to the drawable folder instead of dragging and dropping. Select OK in the pop-up window. You can double-check that the directory listing is correct by looking for drawable listed at the end of the listing.
Double-click the image name under drawable. You have now added an image to a project in Android Studio. Include your email address to get a message when this question is answered. Submit a Tip All tip submissions are carefully reviewed before being published. Related wikiHows How to. How to. About This Article. First of all, this is a Basic ImageDownloader and that's it. All it does is connecting to the given url, reading the data and trying to decode it as a Bitmap , triggering the OnImageLoaderListener interface callbacks when appropriate.
The advantage of this approach - it is simple and you have a clear overview of what's going on. Note: in case of large images, you might need to scale them down. Android DownloadManager is a way to let the system handle the download for you. It's actually capable of downloading any kind of files, not just images. You may let your download happen silently and invisible to the user, or you can enable the user to see the download in the notification area.
You can also register a BroadcastReceiver to get notified after you download is complete. The setup is pretty much straightforward, refer to the linked project for sample code.
Using the DownloadManager is generally not a good idea if you also want to display the image, since you'd need to read and decode the saved file instead of just setting the downloaded Bitmap into an ImageView.
Now the introduction of the great stuff - the libraries. I will start with Volley , a powerful library created by Google and covered by the official documentation. While being a general-purpose networking library not specializing on images, Volley features quite a powerful API for managing images.
You will need to implement a Singleton class for managing Volley requests and you are good to go. You might want to replace your ImageView with Volley's NetworkImageView , so the download basically becomes a one-liner:.
If you need more control, this is what it looks like to create an ImageRequest with Volley:. It is worth mentioning that Volley features an excellent error handling mechanism by providing the VolleyError class that helps you to determine the exact cause of an error. If your app does a lot of networking and managing images isn't its main purpose, then Volley it a perfect fit for you.
Square's Picasso is a well-known library which will do all of the image loading stuff for you. Just displaying an image using Picasso is as simple as:. For more control you can implement the Target interface and use it to load your image into - this will provide callbacks similar to the Volley example. Check the demo project for examples. Picasso also lets you apply transformations to the downloaded image and there are even other libraries around that extend those API.
Universal Image Loader is an another very popular library serving the purpose of image management. It uses its own ImageLoader that once initialized has a global instance which can be used to download images in a single line of code:.
The opts argument in this example is a DisplayImageOptions object. Refer to the demo project to learn more. Note : the author has mentioned that he is no longer maintaining the project as of Nov 27th, But since there are many contributors, we can hope that the Universal Image Loader will live on.
Facebook's Fresco is the newest and IMO the most advanced library that takes image management to a new level: from keeping Bitmaps off the java heap prior to Lollipop to supporting animated formats and progressive JPEG streaming. To learn more about ideas and techniques behind Fresco, refer to this post. The basic usage is quite simple. Note that you'll need to call Fresco.
Initializing Fresco more than once may lead to unpredictable behavior and OOM errors. Fresco uses Drawee s to display images, you can think of them as of ImageView s:.
As you can see, a lot of stuff including transformation options gets already defined in XML, so all you need to do to display an image is a one-liner:. Fresco provides an extended customization API, which, under circumstances, can be quite complex and requires the user to read the docs carefully yes, sometimes you need to RTFM.
Note that the following text reflects my personal opinion and should not be taken as a postulate. In case you missed that, the Github link for the demo project.
I have just came from solving this problem on and I would like to share the complete code that can download, save to the sdcard and hide the filename and retrieve the images and finally it checks if the image is already there. The url comes from the database so the filename can be uniquely easily using id. Why do you really need your own code to download it?
How about just passing your URI to Download manager? I have a simple solution which is working perfectly. The code is not mine, I found it on this link. Here are the steps to follow:. It needs a context, better to use the pass in the application context by getApplicationContext. This method can be dumped into your Activity class or other util classes.
This private class need to be placed in your Activity class as a subclass. After the image is downloaded, in the onPostExecute method, it calls the saveImage method defined above to save the image. The AsyncTask for downloading the image is defined, but we need to execute it in order to run that AsyncTask. To do so, write this line in your onCreate method in your Activity class, or in an onClick method of a button or other places you see fit.
IMO this solves the issue! If you want further steps such as load the image you can follow these extra steps:. After the image is downloaded, we need a way to load the image bitmap from the internal storage, so we can use it. This method takes two paramethers, a context and an image file name, without the full path, the context. Now we have everything we needed for setting the image of an ImageView or any other Views that you like to use the image on.
Droidman post is pretty comprehensive. Volley works good with small data of few kbytes.
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