SpringMVC 文件的上传与下载

一、上传
1.pom依赖

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
</dependency>

2.controller-servlet.xml文件

<!--
    配置文件上传
    id的值必须是multipartResolver

 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="defaultEncoding" value="utf-8"></property>
</bean>

3.jsp文件

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1>文件上传</h1>

<form action="${pageContext.request.contextPath}/hello/load" method="post" enctype="multipart/form-data">
    用户：<input type="text" name="username"/><br>

    文件：<input type="file" name="file"/><br>

    <input type="submit" value="提交">
</form>

</body>
</html>

4.controller
单个文件：

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

    @RequestMapping("/load")//单个文件上传
    public void upload(HttpSession session, @RequestParam("file") CommonsMultipartFile file) throws IOException {

        ServletContext application = session.getServletContext();
        String path = application.getRealPath("/upload/"+new SimpleDateFormat("yyyyMMdd").format(new Date()));


        File f = new File(path);
        f.mkdirs();

        file.transferTo(new File(path,file.getOriginalFilename()));
    }
}

多个文件：

@RequestMapping("/loads")
    public void uploads(HttpSession session, @RequestParam("file") CommonsMultipartFile[] files ) throws IOException {
        ServletContext application = session.getServletContext();
        String path = application.getRealPath("/upload/"+new SimpleDateFormat("yyyyMMdd").format(new Date()));

        File f = new File(path);
        f.mkdirs();
        for(CommonsMultipartFile file : files){//遍历文件存储即可
            file.transferTo(new File(path,file.getOriginalFilename()));
        }

    }

二、下载

@RequestMapping("/download")
    public ResponseEntity<byte[]> download(HttpSession session) throws IOException {

        //new ResponseEntity<byte[]>()
        String path = session.getServletContext().getRealPath("/upload/20200726/xzcs.txt");
        File file = new File(path);
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentDispositionFormData("attachment","cs");
        return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),httpHeaders, HttpStatus.CREATED);
    }

注：如果找不到FileUtils类，需要添加commom-io依赖

<dependency>
	<groupId>commons-io</groupId>
	<artifactId>commons-io</artifactId>
	<version>2.4</version>
</dependency>