SpringMVC执行原理

news2024/11/28 18:57:35

目录结构

pom.xml依赖

<dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.1</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
    </dependency>

    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.0.RELEASE</version>
    </dependency>
  </dependencies>

web.xml

<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">

<!--配置DispatcherServlet，这个是SpringMVC的核心：请求分发器，前端控制器-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--        DispatcherServlet要绑定spring的配置文件-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
<!--        启动级别-->
        <load-on-startup>1</load-on-startup>
    </servlet>


<!--    SpringMVC中，/和/*的区别
   /：只匹配所有的请求，不会去匹配jsp页面
   /*：匹配所有的请求，包括jsp页面
-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

test.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
${msg}
</body>
</html>

springmvc-servlet.xml

<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
     https://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context
      https://www.springframework.org/schema/context/spring-context.xsd">

              <!--处理器映射器-->
    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

              <!--处理器适配器-->
    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

              <!--视图解析器-->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--前缀-->
          <property name="prefix" value="/WEB-INF/jsp/"></property>
        <!--后缀-->
        <property name="suffix" value=".jsp"></property>
    </bean>

    <bean id="/hello" class="com.qing.controller.HelloController"></bean>
</beans>

HelloController

package com.qing.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 {



    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        ModelAndView mv = new ModelAndView();
        // 业务代码
        String result="HelloSpringMVC";
        mv.addObject("msg",result);

        //  视图跳转
        mv.setViewName("test");
        return mv;
    }
}

Spring MVC执行原理：