The HTTP client in the Java class library is interpretable (Interpretation of the Technical Principles of Client Common Framework in Java Class Libraries)

Interpretation of HTTP client universal framework technical principles in the Java class library In the Java class library, there are many frameworks and libraries for HTTP communication.This article will interpret the technical principle of the HTTP client universal framework.The general framework of the HTTP client is an abstract and encapsulation tool for HTTP requests and responses, allowing developers to more conveniently conduct HTTP communication. 1. Overview of the HTTP protocol Before interpreting the universal framework of the HTTP client, let's briefly outline the HTTP protocol.HTTP (Hypertext Transfer Protocol) is a protocol for transmitting super text.It is based on the request-response model and communicates by switch messages between clients and servers.The HTTP protocol uses URL (Uniform Resource Locator) to identify and locate network resources. 2. The general framework of the HTTP client in the Java class library The Java class library provides several general frameworks of HTTP clients. Common Java native UrlConnection classes, Apache's HTTPClient library and Spring RestTemplate class.These frameworks are encapsulated with the processing details of HTTP requests and responses, providing advanced APIs, so that developers can more conveniently send HTTP requests and analytical responses. 3. Technical principles for the general framework of the HTTP client No matter what kind of HTTP client universal framework, some similar technical principles need to be involved in implementation, including URL parsing, request construction, request sending and response processing. 1. URL analysis The general framework of the HTTP client first needs to analyze the URL to obtain information such as protocols, hosts, ports, paths and other information.In general, the Java library will provide related APIs to analyze the URL, such as the java.net.url class. 2. Request construction According to the URL information obtained by the analysis, the general framework of the HTTP client will build an HTTP request through the corresponding API.The request contains information such as the HTTP method (get, post, etc.), the request header, and the request body.Developers can set the request parameters, request header and request body through the API. For example, in the Apache HttpClient library, you can use the HTTPGET or HTTPPOST class to create a GET or POST request object, and set the request head and request body by calling methods such as SetHeader and Setentity. 3. Request sending After the HTTP request is built, the framework will send the request to the designated server.This process generally includes steps such as establishing TCP connection, sending request data, and receiving response data.The specific implementation details may vary from the framework. 4. Response treatment Once the server receives the request and completes the processing, a HTTP response will be returned.The general framework of the HTTP client will receive the response data and analyze and process it.The parsing data includes the response status code, response head, and response. Developers can use the API provided by the framework to obtain the content of the response status code, response head, and response.For example, in the Java's HTTPURLCONNECTION class, you can obtain the response status code, response head and response input stream through the GetresPonsecode, GetHeaderfield, GetinputStream and other methods. Fourth, Java code example The following is an example code that uses the Apache httpClient library to send GET requests: import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.HttpClientBuilder; public class HttpClientExample { public static void main(String[] args) throws Exception { HttpClient httpClient = HttpClientBuilder.create().build(); HttpGet request = new HttpGet("http://www.example.com"); HttpResponse response = httpClient.execute(request); System.out.println("Response Code : " + response.getStatusLine().getStatusCode()); } } In the above code, we first created an HTTPClient object, and then used the HTTPGET class to create a GET request object, and set the requested URL to "http://www.example.com".Finally, we send a request through the httpclient.execute method and obtain the status code from the response. In this way, we can easily use the httpclient library to send HTTP requests and handle response. Summarize: This article interprets the technical principles of the HTTP client universal framework in the Java library.Whether it is using Java's native UrlConnection class, Apache's httpclient library, or Spring's RESTTEMPLATE class, these frameworks provide simple APIs and encapsulate the details of HTTP communication to facilitate developers to handle HTTP requests and responses.Developers can choose a framework that suits them according to specific needs, and better use and expand through the principle of learning framework.