SpringMvc两种实现

SpringMvc搭建

了解mvc

什么是MVC

• MVC是模型(Model)、视图(View)、控制器(Controller)的简写，是一种软件设计规范。
• 是将业务逻辑、数据、显示分离的方法来组织代码。
• MVC主要作用是降低了视图与业务逻辑间的双向偶合。
• MVC不是一种设计模式，MVC是一种架构模式。

最典型的MVC就是JSP + servlet + javabean的模式。

回顾servlet

新建一个Maven工程当做父工程！pom依赖！

<dependencies>
   <dependency>
       <groupId>junitgroupId>
       <artifactId>junitartifactId>
       <version>4.12version>
   dependency>
   <dependency>
       <groupId>org.springframeworkgroupId>
       <artifactId>spring-webmvcartifactId>
       <version>5.1.9.RELEASEversion>
   dependency>
   <dependency>
       <groupId>javax.servletgroupId>
       <artifactId>servlet-apiartifactId>
       <version>2.5version>
   dependency>
   <dependency>
       <groupId>javax.servlet.jspgroupId>
       <artifactId>jsp-apiartifactId>
       <version>2.2version>
   dependency>
   <dependency>
       <groupId>javax.servletgroupId>
       <artifactId>jstlartifactId>
       <version>1.2version>
   dependency>
dependencies>

建立一个Moudle：springmvc-01-servlet ， 添加Web app的支持！

如何添加web app的支持？

​ 【图一】

​ 【图二】

说明：在子模块上右键，点击 Add Framework Support,然后选择，web Application。

HelloServlet

编写一个Servlet类，用来处理用户的请求

package com.feng.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class HelloServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //取得参数
        String method = req.getParameter("method");
        if (method.equals("add")){
            req.getSession().setAttribute("msg","执行了add方法");
        }
        if (method.equals("delete")){
            req.getSession().setAttribute("msg","执行了delete方法");
        }

        //业务逻辑
        //视图跳转
        req.getRequestDispatcher("/WEB-INF/jsp/userForm.jsp").forward(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

编写Hello.jsp，在WEB-INF目录下新建一个jsp的文件夹，新建userForm.jsp。（此处省略）

web.xml

在web.xml中注册Servlet

<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>helloservlet-name>
        <servlet-class>com.feng.servlet.HelloServletservlet-class>
    servlet>
    <servlet-mapping>
        <servlet-name>helloservlet-name>
        <url-pattern>/hellourl-pattern>
    servlet-mapping>
web-app>

启动测试

配置Tomcat，并启动测试

1. http://localhost:8080/hello?method=add

配置版

流程

1、新建一个Moudle ， springmvc-02-hello ， 添加web的支持！

2、确定导入了SpringMVC 的依赖！

3、配置web.xml ， 注册DispatcherServlet

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>

springmvc-servlet.xml

<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">

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


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

beans>

controller

package com.feng.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 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;
    }
}

jsp页面

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


    


    ${msg}

启动

地址：http://localhost:8080/hello

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-pZqAR21T-1615728028991)(C:\Users\fjh\AppData\Roaming\Typora\typora-user-images\image-20210314153207223.png)]

404情况

可能遇到的问题：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！

添加lib依赖（控制台正常）

说明：很明显WEB-INF目录下缺少lib目录，手动新建然后添加所有jar包，重启再试。

添加lib

成功启动

注解版

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>

springmvc-servlet.xml

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

    
    <context:component-scan base-package="com.feng.controller"/>
    
    <mvc:default-servlet-handler />
    
    <mvc:annotation-driven />

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

beans>

创建Controller

package com.feng.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/HelloController")
public class HelloController {

    //真实访问地址 : 项目名/HelloController/hello
    @RequestMapping("/hello")
    public String sayHello(Model model){
        //向模型中添加属性msg与值，可以在JSP页面中取出并渲染
        model.addAttribute("msg","hello,SpringMVC");
        //web-inf/jsp/hello.jsp
        return "hello";
    }
}

省略jsp

启动成功