Introduction to Volley

Volley is an open-source library written by Google (Android team), released during Google I/O 2013.

Transcript

1. Introduction to Volley Paresh Mayani
2. Paresh Mayani Sr. Software Engineer @ InfoStretch, India Manager, GDG Ahmedabad
3. Writing Http code every time? {Less code} {Less Mistakes} {Faster Development}
4. Volley Simultaneous firing of a number of missiles
5. Volley library o An open-source library written by Google (Android team) o Volley isn’t an image loading library - it’s an asynchronous networking library o Introduced by Ficus Kirkpatrick at Google I/O 2013 o It’s not yet added to Android API
6. Advantages o Standalone library o A high level API to make asynchronous RESTful HTTP requests o Schedules all your HTTP requests running them parallel in background threads and manages those threads. o Good asynchronous performance o Provides powerful cancellation request API. o Comes with inbuilt JSON parsing the response. o Handles memory errors well o Retry policy for timeout, certain ERROR codes as Internal Server error.
7. Disadvantages o It’s not well documented o No active contributors o Advanced HTTP features need custom code
8. Get Volley $ git clone https://android.googlesource.com/platform/frameworks/volley $ cd volley $ android update project -p . $ ant jar
9. Let’s use Volley Step 1: Create a RequestQueue Instance Step 2: Create a JSONObjectRequest with response and error listener. Step 3: Add your request into the RequestQueue.
10. Step 1 Create a RequestQueue Instance RequestQueue queue = Volley.newRequestQueue(this);
11. Step 2 To make asynchronous HTTP requests, there are 3 utility classes available: JsonObjectRequest - To send and receive JSON Object from the Server JsonArrayRequest - To receive JSON Array from the Server StringRequest - To retrieve response body as String (ideally if you intend to parse the response by yourself)
12. Step 2 Create a JSONObjectRequest with response and error listener. JsonObjectRequest jsObjRequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() { @Override public void onResponse(JSONObject response) { // TODO Auto-generated method stub } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { // TODO Auto-generated method stub } });
13. Step 3 Add your request into the RequestQueue queue.add(jsObjRequest);
14. Image loading using Volley Step 1: Get NetworkImageView in XML layout Step 2: Create ImageLoader object Step 3: Load Image using setImageUrl(url, imageLoader)
15. Image loading using Volley <com.android.volley.toolbox.NetworkImageView android:id="@+id/imgDemo" android:layout_width="wrap_content" android:layout_height="wrap_content" android:scaleType="centerCrop"/> ImageLoader.ImageCache imageCache = new BitmapLruCache(); ImageLoader imageLoader = new ImageLoader(Volley.newRequestQueue(context), imageCache); NetworkImageView imgDemo = (NetworkImageView) findViewById(R.id.imgDemo); imgDemo.setImageUrl(url, imageLoader); imgDemo.setDefaultImageResId(..); imgDemo.setErrorImageResId(..);
16. References/links o https://android.googlesource.com/platform/frameworks/volley/ o https://developers.google.com/events/io/sessions/325304728
17. Thank You +PareshMayani @pareshmayani TechnoTalkative.com