SpringMVC

MVC

  • 模型（Model） 【dao service】
  • 视图（View）【jsp】
  • 控制器（Controller）【Servlet】

SpringMVC特点：

  1. 轻量级
  2. 高校，基于请求响应的MVC框架
  3. 功能强大：RESTful、数据验证、格式化、本地化、主题等

DispatcherServlet

1 SpringMVC的配置

  1. 新建Moudle，添加web依赖

    image-20201217163825967

  2. 导入相关依赖

  3. 配置web.xml，注册DispatcherServlet

    web.xml

    <?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">

    <!-- 注册DispatcherServlet (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>
        <!-- DispatchServlet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>

    <!--
     / : 只匹配所有的请求，不会匹配jsp页面
     /* : 配置所有的请求，包括jsp页面
     -->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

    springmvc-servlet.xml:

    <?xml version="1.0" encoding="UTF-8"?>
<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
        https://www.springframework.org/schema/beans/spring-beans.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 : 模板引擎 Thymeleaf Freemarker...-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/jsp/" />
        <!-- 后缀 -->
        <property name="suffix" value=".jsp" />
    </bean>


   <!-- BeanNameUrlHandlerMapping:要配置bean -->
   <bean id="/hello" class="com.Rickduck.controller.HelloController" />
```

问题：页面显示404，打包的target中缺少lib文件夹

解决： Project Structure -- Artifacts 中添加lib文件夹并将jar包导入

2. SpringMVC执行流程

1608957308884

3. 使用注解开发SpringMVC

  1. 注解配置

web.xml配置DispatchServlet：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
         version="5.0">
    <!-- 注册DispatcherServlet (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>
        <!-- DispatchServlet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>

    <!--
     / : 只匹配所有的请求，不会匹配jsp页面
     /* : 配置所有的请求，包括jsp页面
     -->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>



</web-app>

springmvc配置：

<?xml version="1.0" encoding="UTF-8"?>
<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
        https://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">


    <!-- 自动扫描包，让指定包下的注解生效 -->
    <context:component-scan base-package="com.Rickduck.Controller" />
    <mvc:default-servlet-handler />
    <mvc:annotation-driven />

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

</beans>

  1. 编写控制类及页面跳转关系

    package com.Rickduck.Controller;

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

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

    @RequestMapping("/h1")
    public String hello(Model model){

        model.addAttribute("msg","Hello SpringMVC");

        return "hello";
    }
}

  2. web页面

<%--
  Created by IntelliJ IDEA.
  User: 63008
  Date: 2020/12/26
  Time: 13:01
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Hello</title>
</head>
<body>

    ${msg}

</body>
</html>

注解

//识别前端的对象名
@RequestParam("username") String name

4. Restful风格

通过请求的方式进行判断

功能

  • 资源：忽略文所有事物都可抽象为资源
  • 资源操作（不同请求方式）
    • POST：添加
    • DELETE：删除
    • PUT：修改
    • GET：查询

方法级别注解，组合注解：

@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping

好处：

  • 使路径边的更加简洁（安全）
  • 支持缓存
  • 获得参数更加方便，框架会自动进行类型转换
  • 通过路径变量类型可以约束访问参数

5. 转发与重定向

SpringMVC实现转发和重定向

@Controller
public class RestfulController {

    //转发
    @GetMapping("/add/a/b")
    public String test1(@PathVariable int a,@PathVariable int b, Model model){

        model.addAttribute("msg",a+b);
        return "hello";
    }

    //重定向
    @RequestMapping("/test")
    public String test2(){
        return "redirect:/hello.jsp";
    }
}

6. Json

依赖导入：

        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.0</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
            <scope>provided</scope>
        </dependency>

6.1Jackson

Jackson乱码配置：

在springMVC配置文件中设置：

<!--JSON乱码问题配置-->
    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="UTF-8"/>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                        <property name="failOnEmptyBeans" value="false"/>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

7. 拦截器

  • 自带静态资源过滤
  • 指挥访问拦***问的控制方法
  • 新建一个config文件，添加MyInterceptor类并实现HandlerInterceptor接口
  • 重写拦截方法 
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

public class MyInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}
  • 配置springmvc-config，添加拦截器配置 
<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/**"/>
        <bean class="com.Rickduck.config.MyInterceptor" />
    </mvc:interceptor>
</mvc:interceptors>

8. 文件上传

  • 导入pom依赖 
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.4</version>
</dependency>
  • 配置springmvc-config文件，注入相关Bean 
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="utf-8" />
        <property name="maxUploadSize" value="10485760"/>
        <property name="maxInMemorySize" value="40960" />
    </bean>
  • 设置表单提交的类型 
<form action = "${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
    <input type = "file" name = "file" />
    <input type = "submit" value = "upload" />
</form>
  • 编写Controller类添加文件 
    @RequestMapping("upload")
    public String fileLoad(@RequestParam("file")CommonsMultipartFile file, HttpServletRequest request) throws IOException {

        //上传路径
        String path = request.getServletContext().getRealPath("/upload");
        File realPath = new File(path);
        if(!realPath.exists()){
            realPath.mkdir();
        }

        //上传文件地址
        System.out.println(realPath);

        //通过CommonsMultipartFile提供的方法直接写文件
        file.transferTo(new File(realPath+"/"+file.getOriginalFilename()));

        return "test";

    }