SpringMVC的文件上传，首先来分析一下：
SpringMVC的工作流程 大概是止戈样的，首先前端页面发来请求，会被DispatcherServlet拦截到，通过对SpringMVC配置文件中配置文件解析器，最后返回一个MutipartFile对象，我们在controller中通过该对象来接收，在进行存储，总的来说就是省去了我们自己进行文件解析的操作！那我们来配置一个完整的小demo。
第一步，导入所有需要用到的pom依赖
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet/servlet-api -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.4</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.6</version>
</dependency>
</dependencies>
第二步，web.xml中配置一下前端控制器，编码过滤器习惯性的配上
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>dispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>dispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
加载时扫描的springmvc.xml我们需要配置一下，单纯只是想要文件上传的话这里其实可以不需要配置静态资源
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
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
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- 开启自动扫描 -->
<context:component-scan base-package="com.lp"/>
<!-- 注册SpringMVC注解开发驱动 -->
<mvc:annotation-driven/>
<!-- 视图解析器-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 前缀 -->
<property name="prefix" value="/WEB-INF/pages/"></property>
<!-- 后缀 -->
<property name="suffix" value=".jsp"></property>
</bean>
<!-- 前端控制器，哪些静态资源不拦截-->
<mvc:resources mapping="/js/**" location="/js/"/>
<mvc:resources mapping="/css/**" location="/css/"/>
<mvc:resources mapping="/img/**" location="/img/"/>
<!-- 配置文件解析器，id必须为multipartResolver-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="10485760"/>
</bean>
</beans>
controller层的文件上传代码
package com.lp.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.util.UUID;
/**
* @Date 2020/6/4 19:56
* @Author luopeng
*/
@Controller
@RequestMapping("/user")
public class UserController {
@RequestMapping("/fileUpload1")
//upload名字必须与表单那么一致
public String fileUpLoad1(HttpServletRequest request, MultipartFile upload) throws IOException {
System.out.println("文件上传中...");
//上传位置
String path = request.getSession().getServletContext().getRealPath("/uploads/");
// 判断路径是否存在
File file = new File(path);
if (!file.exists()) {
//如果不存在就创建文件夹
file.mkdirs();
}
//获取上传文件的名称
String filename = upload.getOriginalFilename();
//把文件上传的名称设置唯一值，UUID
//UUID.randomUUID().toString()默认生成的格式是这样的96e5a2db-66b5-4cbe-97dd-c9431b48bf06
//我们利用字符串的replace()方法将它的连接线去掉
String uuid = UUID.randomUUID().toString().replace("-", "");
//文件的完整名称就是 生成的唯一值_上传时的文件名
filename = uuid + "_" + filename;
//完成文件上传，new File(path, filename)为其指定目录和自己的文件名
upload.transferTo(new File(path, filename));
return "success";
}
}
页面首页
<%--
Created by IntelliJ IDEA.
User: LuoPeng
Date: 2020/6/4
Time: 19:55
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>文件上传</title>
</head>
<body>
<%--提交方式：post，enctype要设置为multipart/form-data"--%>
<form action="/user/fileUpload1" method="post" enctype="multipart/form-data">
选择文件：<input type="file" name="upload"><br>
<input type="submit" value="提交">
</form>
</body>
</html>
上传成功跳转到success页面
<%--
Created by IntelliJ IDEA.
User: LuoPeng
Date: 2020/6/4
Time: 19:58
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>上传成功</title>
</head>
<body>
<h3>上传文件成功</h3>
</body>
</html>
用的jsp，别介意哈，毕竟我很垃圾，啥也不会，哎
