The basic principles and usage methods of the Apache HTTPCORE framework

The Apache HTTPCORE framework is a Java framework for building a client and server based on the HTTP protocol.It is part of the Apache HTTPCOMPONENTS project, which provides some core components for handling HTTP requests and responses. ### Basic principle The basic principle of the Apache HTTPCORE framework is to achieve HTTP requests and responses by defining each component of the HTTP protocol.It mainly involves the following key concepts: 1. ** HTTP request **: The HTTPCORE framework allows developers to build HTTP requests and send them to the server.HTTP request consists of HTTP method, URI, HTTP header and optional request body. 2. ** http response **: The HTTPCORE framework allows developers to receive the HTTP server response.HTTP response includes a status code, HTTP header and optional response. 3. ** Connection Management **: The HTTPCORE framework provides connection management functions, including creating, closing and managing HTTP connection.It uses the connection manager to manage the reuse of connection to improve performance and efficiency. 4. ** Request execution **: HTTPCORE framework allows developers to perform HTTP requests and process HTTP responses.The request actuator is responsible for sending the request to the target server and processing the response of the server. 5. ** protocol processor **: The HTTPCORE framework uses protocol processor to process the encoding of the HTTP request and response.It defines the method of converting HTTP messages into Java objects, and the method of converting Java objects into HTTP messages. ### Instructions The following are the basic steps for the development of the HTTP client and server development with the Apache HTTPCORE framework. 1. ** Add dependence **: First of all, you need to add the dependencies of the Apache HTTPCORE framework to the project.You can download and add jar files through Maven or manually. <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpcore</artifactId> <version>4.4.13</version> </dependency> 2. ** Create http client **: Use `httpclients.createdefault ()` method to create a default HTTP client instance. CloseableHttpClient httpClient = HttpClients.createDefault(); 3. ** Execute HTTP request **: Create a HTTP request object, set the request method, URI, head and body, and use the `httpclient.execute () method to execute the request. HttpGet httpGet = new HttpGet("http://example.com"); CloseableHttpResponse response = httpClient.execute(httpGet); 4. ** Treatment of http response **: Get the status code, head and body from the response, and process it as needed. int statusCode = response.getStatusLine().getStatusCode(); Header[] headers = response.getAllHeaders(); HttpEntity entity = response.getEntity(); // Treat the response body EntityUtils.consume(entity); 5. ** Close the http client and response **: Remember to close them to release the resources after using the HTTP client and response. response.close(); httpClient.close(); 6. ** Create http server **: Use the `httpserver.create () method to create a HTTP server instance, and set the port number, processing program and parameters. HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0); server.createContext("/", new MyHttpHandler()); Server.Setexecutor (null); // Use the default actuator server.start(); 7. ** Implement the request processing program **: Implement the custom request processing program of the `httphandler` interface, process the HTTP request and send a response. class MyHttpHandler implements HttpHandler { public void handle(HttpExchange exchange) throws IOException { String response = "Hello, World!"; exchange.sendResponseHeaders(200, response.getBytes().length); OutputStream outputStream = exchange.getResponseBody(); outputStream.write(response.getBytes()); outputStream.close(); } } 8. ** Turn off the http server **: After completing the use of the HTTP server, make sure to use the `Server.stop ()` to close the server. server.stop(0); The above is the method of using the Apache HTTPCORE framework to develop the basic HTTP client and server development.According to actual needs, other functions and extensions provided by the framework can also be used.