【WEEK1】【DAY5】First MVC Program: Configuration File【English Version】

2024.3.1 Friday

3. First MVC Program
- 3.1 Configuration files

3. First MVC Program

3.1 Configuration files

3.1.1. Create a new module

Create a new module named springmvc-02-hello and add web support

3.1.2. Modify web.xml, add content

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <!--1. Register DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--Associate a springmvc configuration file: 【servlet-name】-servlet.xml-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>  <!--Need to write a configuration file-->
        </init-param>
        <!--Startup level-1-->
        <load-on-startup>1</load-on-startup>
<!--   the above should be ignored at this time     -->

    </servlet>

    <!--/ Matches all requests except .jsp-->
    <!--/* Matches all requests including .jsp-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>  <!--All requests will go through this-->
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

3.1.3. Write the SpringMVC configuration file

Name: springmvc-servlet.xml: [servletname]-servlet.xml
Note that the name should follow the official convention
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3.1.4. Add handler mappings, handler adapters, and view resolvers

Complete code located at 3.1.7

<!--Configure three classes: can be directly reused-->

    <!--  Handler Mapping  -->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

    <!--  Handler Adapter -->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

    <!--View Resolver: DispatcherServlet gives it the ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--Prefix-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--Suffix-->
        <property name="suffix" value=".jsp"/>
    </bean>

3.1.5. Write specific business operations

Write our business Controller, either implement the Controller interface or add annotations; need to return a ModelAndView, pack data, seal the view;
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package com.kuang.controller;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloController implements Controller {    //Choose the interface type for the imported Controller
//    Implementing a controller interface allows handling of request and response
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //ModelAndView model and view
        ModelAndView mv = new ModelAndView();

        //Encapsulate the object, put it in ModelAndView. Model
        mv.addObject("msg","HelloSpringMVC!");
        //Encapsulate the view to jump to, put it in ModelAndView
        mv.setViewName("hello"); //: /WEB-INF/jsp/hello.jsp
        return mv;
    }
}

3.1.6. JSP page to jump to, display the data stored in ModelAndView, and the normal page

Create a folder named jsp, hello.jsp file
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<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    ${msg}  <!--Able to take out the message from the control: mv.addObject("msg","HelloSpringMVC!");-->
</body>
</html>

3.1.7. Register your own class with the Spring IOC container, register bean

The bold part is newly added in this section, the rest are the previous two sections
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