The working principle and architecture solution of Volley framework

The Volley framework is a network request library commonly used in Android development. It is not only used to send network requests, but also to handle tasks such as picture loading.This article will introduce the working principle and architecture of the Volley framework and provide Java code examples. 1. Working principle Volley's working principle can be divided into three main steps: the management of the queue, the distribution and response processing of the request. 1. Request queue management: In Volley, there is a RequestQueue to manage all network requests.A request queue is maintained inside the request queue to store requests to be treated.When the ADD () method of RequestQueue is added to the queue, Volley will be arranged according to the request priority. 2. Send issuance of requests: The request queue will constantly take out the request from the request queue, and then send it to the appropriate request processor.Volley has four built -in request processors: StringRequest, JSONObjectRequest, JSONARRAYRequest, and ImageEquest for processing different types of requests.When the request is sent, the request processor will send the request to the server and wait for the server to return the response. 3. Response processing: When the server returns the response, the request processor will give the response to the appropriate parser for analysis. The analysis results can be a string, a JSON object, a JSON array or bitmap.Then, the request processor will return the resolution results to the caller by the callback function. 2. Architecture Analysis Volley's architecture can be divided into four main modules: request modules, network request modules, cache modules and response modules. 1. Request module: Volley's request module consists of Request and RequestQueue.Request is an abstract class. The subclass of the specific request type will inherit it and implement some necessary methods, such as PARESNETWORKRESPONSE () to analyze network response.RequestQueue is responsible for the management request queue, including adding requests, canceling requests, execution requests and other functions. 2. Network request module: Volley's network request module consists of network and various Request classes.Network defines the interface of the network request, and the request is usually implemented through its subclass BasicNetwork.Various Request classes are responsible for specific network request operations, such as initiating requests and processing responses. 3. Cache module: Volley's cache module is responsible for the cache work of requesting data to reduce the number of network requests.Volley provides a default cache to implement DiskBasedCache, which can storage the response result of the request in a key value pair. 4. Response module: Volley's response module is responsible for handling the request results, including parsing response data and transmission results to the callback function.Volley has a built -in parser, such as StringRequest is used to analyze the string response, JSONObjectRequest is used to analyze the JSON object response. The following is an example of Java code required to send network requests using Volley: // Create a request queue RequestQueue requestQueue = Volley.newRequestQueue(context); // Create a StringRequest request StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() { @Override public void onResponse(String response) { // Request successful callback processing results Log.d(TAG, "Response: " + response); } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { // Request failure recovery processing error Log.e(TAG, "Error: " + error.getMessage()); } }); // Add the request to the queue requestQueue.add(stringRequest); The above code first created a request queue, and then created a StringRequest request, specified the method and URL of the request, and set a successful and failed callback function.Finally add the request to the queue. Summarize: Through this article, we understand the working principle and architecture of the Volley framework.Volley uses the distribution and processing of the request queue management request, supports various request types, and provides cache and analytical functions.By using Volley reasonably, we can simplify the network request operation in Android applications to improve development efficiency.