JavaWeb study notes 20/10/12Servlet

Servlet

1. 1 Introduction to Servlet

• Servlet is a technology developed by Sun to develop dynamic Web. The Java program that implements the Servlet interface is called Servlet.
• Sun provides an interface in these APIs called: Servlet, if you want to develop a Servlet program, you only need to complete two small steps:
  • Write a class to implement the Servlet interface
  • Deploy the developed Java classes to the web server

1. 2 HelloServlet

Serlvet interface Sun has two default implementation classes: HttpServlet, GenericServlet

1. Understanding of the Maven father and son project:

   There will be:

       <modules>
           <module>servlet-01</module>
       </modules>
   

   There will be:

       <parent>
           <artifactId>javaweb-02-servlet</artifactId>
           <groupId>com.weng</groupId>
           <version>1.0-SNAPSHOT</version>
       </parent>
   

   The jar package subproject in the parent project can be used directly

   son extends father
   

2. Maven environment optimization

   • Modify web.xml to the latest
   • Complete the structure of maven

3. Write a Servlet program

   • Write a normal class
   • Implement Servlet interface, here directly inherit Http

   public class HelloServlet extends HttpServlet {
         
         
       //由于get或post只是请求实现的不同方式,可以相互调用,业务逻辑一样
       @Override
       protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         
         
           System.out.println("进入doGet方法");
           //ServletOutputStream outputStream = resp.getOutputStream();
           PrintWriter writer = resp.getWriter();//响应流
           writer.print("Hello,Servlet");
       }
   
       @Override
       protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         
         
           doPost(req, resp);
       }
   }
   

4. Write Servlet mapping

   Why do I need to map?

   We write a Java application, but we need to access it through a browser, and the browser needs to connect to the Web server, so we need to register the Servlet we wrote in the Web service, and we need to give it a path that the browser can access;

   <servlet>
       <servlet-name>hello</servlet-name>
       <servlet-class>com.weng.servlet.HelloServlet</servlet-class>
   </servlet>
   <servlet-mapping>
       <servlet-name>hello</servlet-name>
       <url-pattern>/hello</url-pattern>
   </servlet-mapping>
   

5. Configure Tomcat

   Pay attention to the path of project release

6. Start the test