Java Servlet API source code analysis
Java Servlet API is a core technology in Java for the development of web applications.It provides a Java -based programming model to process requests from the web browser and generate response.
Java Servlet API is an open source technology that allows developers to expand and customize according to their needs.It is based on Java programming language and object -oriented programming concepts, enabling developers to use Java to write server -side web applications.
In Java Servlet API, the most important class is Javax.Servlet.servlet interface.All services must implement this interface to process client requests.Servlet is a small application similar to the server, which can respond to the request sent by the client and generate a corresponding response.
The following is a simple example, demonstrating how to write a basic service:
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class MyServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Hello World Servlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Hello World!</h1>");
out.println("</body>");
out.println("</html>");
}
}
In the above example, we created a class called MyServlet, which inherited from javax.servlet.http.httpServlet class.We cover the Doget method, which is used to handle the GET request from the client.In this method, we set the type of response to "Text/HTML" to obtain the output stream and use the Println method to output some HTML marks.
In order to map this service to a URL on the web server, we need to configure the following in the web.xml file:
<servlet>
<servlet-name>MyServlet</servlet-name>
<servlet-class>com.example.MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MyServlet</servlet-name>
<url-pattern>/myservlet</url-pattern>
</servlet-mapping>
Through the above configuration, when accessing the "/MyServlet" path, the web server will call the Doget method of the MyServlet class and return the result to the client.
The Java Servlet API also provides many other useful classes and interfaces, which are used to handle the reading and operation, and jumping of seminars management, requests and response.In actual development, developers can use these classes and interface expansion and customized web applications as needed.
To sum up, the Java Servlet API provides a standard way to develop a web application in Java.It is one of the core technologies of writing server -side applications using Java. It has the characteristics of open source code and can be expanded and customized according to demand.Whether it is to develop simple static web pages or complex dynamic websites, Java Servlet API is one of the indispensable tools.
