Introduction to Java Servlet API framework

Introduction to Java Servlet API framework Java Servlet is a Java API for Web -based applications.Servlet runs on the web server as the middle layer between the client and the server, which is used to process requests from the client and generate response.Servlet can accept various types of requests (such as get, post, etc.) and perform appropriate operations according to the type of request type. The Servlet API provides a set of interfaces and classes for developers to create and manage Servlet.Its main class is javax.servlet.servlet, and all Servlet must implement this interface.Servlet can simplify the development process by inheriting javax.servlet.gnericservlet class or javax.servlet.httpservlet class. The following is a simple Servlet example code. It accepts a GET request parameter called "Name" and shows "Hello, name!" In the response:: import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class HelloWorldServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name = request.getParameter("name"); response.setContentType("text/html"); response.getWriter().println("<h1>Hello, " + name + "!</h1>"); } } To use this service, we need to deploy it to a web server that meets the SERVLET specification, such as Apache Tomcat.After deployment, we can execute the service through accessing the URL, such as "http:// localhost: 8080/HelloWorldServlet? Name = John". The Servlet API also provides many other functions, such as session management, authentication, filter, listener, etc.Session management allows Servlet to track status information related to specific users.Authentication is used to verify the identity of the user and determines whether it has the right to access the protected resources.Filters can be used to prepare and post -processing before requesting to serve or respond to the client.The listener is used to monitor events in the Servlet container, such as the creation, destruction, the beginning and end of the session of the Servlet. To sum up, the Java Servlet API framework provides a way to build scalable, high -performance and secure web applications on the web server.It provides developers with powerful tools for processing HTTP requests and generating HTTP responses, and provides many additional functions to support session management, authentication, filters, etc.By using the Java Servlet API, developers can create excellent web applications to meet changing needs.