SpringMVC 学习（二）Hello SpringMVC

3. Hello SpringMVC

(1) 新建 maven 模块

springmvc-02-hellomvc

(2) 确认依赖的导入

(3) 配置 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">
    
    <servlet>
        <servlet-name>springmvcservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        
        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>classpath:springmvc-servlet.xmlparam-value>
        init-param>
        
        <load-on-startup>1load-on-startup>
    servlet>
    
    
    <servlet-mapping>
        <servlet-name>springmvcservlet-name>
        <url-pattern>/url-pattern>
    servlet-mapping>
web-app>

(4) 编写 springmvc 配置文件

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
beans>

(5) 添加处理映射器

<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

(6) 添加处理适配器

<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

(7) 添加视图解析器

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
    
    <property name="prefix" value="/WEB-INF/jsp/"/>
    
    <property name="suffix" value=".jsp"/>
bean>

(8) 编写 Controller

// com/why/controller/HelloController
package com.why.controller;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//注意：这里我们先导入Controller接口
public class HelloController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        //ModelAndView 模型和视图
        ModelAndView mv = new ModelAndView();
        //封装对象，放在ModelAndView中。Model
        mv.addObject("msg","HelloSpringMVC!");
        //封装要跳转的视图，放在ModelAndView中
        mv.setViewName("hello"); //: /WEB-INF/jsp/hello.jsp
        return mv;
    }
}

(9) 注册 Controller

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

(10) 跳转 jsp 页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    


    ${msg}

(11) 问题排查

• 访问出现404，排查步骤：

  (1) 查看控制台输出，看一下是不是缺少了什么jar包。

  (2) 如果jar包存在，显示无法输出，就在IDEA的项目发布中，添加lib依赖！

  (3) 重启Tomcat 即可解决！