文件上传是一个项目里经常要用的功能, Spring MVC 通过配置一个MultipartResolver 来上传文件。
在Spring 的控制器中,通过MultipartFile file 来接收文件,通过MultipartFile[] files 接收多个文件上传。



(1) 添加文件上传依赖。

<!-- 文件上传 -->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>${commons.fileupload}</version>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>${common.io.version}</version>
        </dependency>



(2)上传页面。在src/main/resources/views 下新建upload.jsp 。

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" isELIgnored="false" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <meta charset="UTF-8">
    <title>upload page</title>
</head>
<body>
    <div class="upload">
        <form action="upload" enctype="multipart/form-data" method="post">
            <input type="file" name="file"/><br>
            <input type="submit" value="上传">
        </form>
    </div>
</body>
</html>



(3) 添加转向到upload 页面的ViewController。

/**
     * 配置中重写addViewControllers来简化配置
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/index").setViewName("/index");
        registry.addViewController("/error").setViewName("/error");
        registry.addViewController("/toUpload").setViewName("/upload");
    }



(4) MultipartResolver 配置。

/**
     * 文件上传表单的视图解析器
     */
    @Bean
    public MultipartResolver multipartResolver(){
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        multipartResolver.setMaxUploadSize(1000000);
        multipartResolver.setDefaultEncoding("UTF-8");
        return multipartResolver;
    }



(5) 控制器。

package com.discry.springboot_in_action.ch4_4;

import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;

@Controller
public class UploadController {

    @RequestMapping(value="/upload",method = RequestMethod.POST)
    public @ResponseBody String upload(MultipartFile file){//使用MultipartFile file 接受上传的文件。
        try {
            //使用FileUtils. writeByteArrayToFile 快速写文件到磁盘
            FileUtils.writeByteArrayToFile(new File("e:/upload/"+file.getOriginalFilename()),file.getBytes());
            return "ok";
        }catch (Exception ex){
            ex.printStackTrace();
            return "error";
        }
    }
}



(6) 运行结果