Volley Library in Android (original) (raw)
Last Updated : 6 Jan, 2025
**Volley is an **HTTP library that makes networking very easy and fast, for Android apps. It was developed by Google and introduced during Google I/O 2013. It was developed because there is an absence in Android SDK, of a networking class capable of working without interfering with the user experience. Although Volley is a part of the Android Open Source Project(AOSP), Google announced in January 2017 that Volley will move to a standalone library. It manages the processing and caching of network requests and it saves developers valuable time from writing the same network call/cache code again and again. Volley is **not suitable for large download or streaming operations since Volley holds all responses in memory during parsing.
**Features of Volley:
- Request queuing and prioritization
- Effective request cache and memory management
- Extensibility and customization of the library to our needs
- Cancelling the requests
**Advantages of Using Volley
- All the tasks that need to be done with Networking in Android, can be done with the help of Volley.
- Automatic scheduling of network requests.
- Catching
- Multiple concurrent network connections.
- Cancelling request API.
- Request prioritization.
- Volley provides debugging and tracing tools.
**How to Import Volley and Add Permissions
Before getting started with Volley, one needs to import Volley and add permissions in the Android Project. The steps to do so are as follows:
**Create a new project. Open **build.gradle(Module: app) and add the following dependency:
dependencies{
//...
implementation 'com.android.volley:volley:1.2.1'
}
In **AndroidManifest.xml add the internet permission:
<****uses-permission** android:name="android.permission.INTERNET" />
**Classes in Volley Library
Volley has two main classes:
- **Request Queue: It is the interest one uses for dispatching requests to the network. One can make a request queue on demand if required, but typically it is created early on, at startup time, and keep it around and use it as a Singleton.
- **Request: All the necessary information for making web API call is stored in it. It is the base for creating network requests(GET, POST).
**Types of Request using Volley Library
**There are many types of request using Volley Library mentioned below:
**1. String Request
Java `
String url = "https:// string_url/"; StringRequest stringRequest = new StringRequest( Request.Method.GET, url, new Response.Listener() { @Override public void onResponse(String response) {
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error)
{
}
}); requestQueue.add(stringRequest);
`
**2. JSONObject Request
Java `
String url = "https:// json_url/"; JsonObjectRequest jsonObjectRequest = new JsonObjectRequest( Request.Method.GET, url, null, new Response.Listener() { @Override public void onResponse(JSONObject response) { } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { } }); requestQueue.add(jsonObjectRequest);
`
**3. JSONArray Request
Java `
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest( Request.Method.GET, url, null, new Response.Listener() { @Override public void onResponse(JSONArray response) { } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { } }); requestQueue.add(jsonArrayRequest);
`
**4. Image Request
Java `
int max - width = ...; int max_height = ...;
String URL = "http:// image_url.png";
ImageRequest imageRequest = new ImageRequest(URL, new Response.Listener() { @Override public void onResponse(Bitmap response) { // Assign the response // to an ImageView ImageView imageView = (ImageView) findViewById( R.id.imageView);
imageView.setImageBitmap(response);
}
},
max_width, max_height, null); requestQueue.add(imageRequest);
`
**5. Adding Post Parameters
Java `
String tag_json_obj = "json_obj_req";
String url = "https:// api.xyz.info/volley/person_object.json";
ProgressDialog pDialog = new ProgressDialog(this); pDialog.setMessage("Loading...PLease wait"); pDialog.show();
JsonObjectRequest jsonObjReq = new JsonObjectRequest( Method.POST, url, null, new Response.Listener() {
@Override
public void onResponse(JSONObject response)
{
Log.d(TAG, response.toString());
pDialog.hide();
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error)
{
VolleyLog.d(TAG, "Error: "
+ error.getMessage());
pDialog.hide();
}
}) {
@Override
protected Map getParams()
{
Map params = new HashMap();
params.put("name", "Androidhive");
params.put("email", "abc@androidhive.info");
params.put("password", "password123");
return params;
}
}; AppController.getInstance() .addToRequestQueue(jsonObjReq, tag_json_obj);
`
**6. Adding Request Headers
Java `
String tag_json_obj = "json_obj_req";
String url = "https:// api.androidhive.info/volley/person_object.json";
ProgressDialog pDialog = new ProgressDialog(this); pDialog.setMessage("Loading..."); pDialog.show();
JsonObjectRequest jsonObjReq = new JsonObjectRequest( Method.POST, url, null, new Response.Listener() {
@Override
public void onResponse(JSONObject response)
{
Log.d(TAG, response.toString());
pDialog.hide();
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error)
{
VolleyLog.d(TAG, "Error: "
+ error.getMessage());
pDialog.hide();
}
}) {
@Override
public Map getHeaders() throws AuthFailureError
{
HashMap headers = new HashMap();
headers.put("Content-Type", "application/json");
headers.put("apiKey", "xxxxxxxxxxxxxxx");
return headers;
}
}; AppController.getInstance() .addToRequestQueue(jsonObjReq, tag_json_obj);
`
**7. Handling the Volley Cache
Java `
// Loading request from cache Cache cache = AppController.getInstance() .getRequestQueue() .getCache();
Entry entry = cache.get(url); if (entry != null) { try { String data = new String(entry.data, "UTF-8"); // handle data, like converting it // to xml, json, bitmap etc., } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } } else { // If cached response doesn't exists }
// Invalidate cache AppController.getInstance() .getRequestQueue() .getCache() .invalidate(url, true);
// Turning off cache // String request StringRequest stringReq = new StringRequest(....);
// disable cache stringReq.setShouldCache(false);
// Deleting cache for particular cache AppController.getInstance() .getRequestQueue() .getCache() .remove(url);
// Deleting all the cache AppController.getInstance() .getRequestQueue() .getCache() .clear(url);
`
**8. Cancelling Request
Java `
// Cancel single request String tag_json_arry = "json_req";
ApplicationController.getInstance() .getRequestQueue() .cancelAll("feed_request");
// Cancel all request ApplicationController.getInstance() .getRequestQueue() .cancelAll();
`
**9. Request Prioritization
Java `
private Priority priority = Priority.HIGH;
StringRequest strReq = new StringRequest( Method.GET, Const.URL_STRING_REQ, new Response .Listener() {
@Override
public void onResponse(String response) {
Log.d(TAG, response.toString());
msgResponse.setText(response.toString());
hideProgressDialog();
} },
new Response
.ErrorListener() {
@Override
public void
onErrorResponse(VolleyError error) {
VolleyLog.d(TAG,
"Error: "
+ error.getMessage());
hideProgressDialog();
} }) {
@Override
public Priority getPriority()
{
return priority;
}
}; `