springmvc文件上传下载实现起来非常简单，此springmvc上传下载案例适合已经搭建好的ssm框架(spring+springmvc+mybatis)使用，ssm框架项目的搭建我相信你们已经搭建好了，这里不再赘述，下面就开始吧！
ssm框架整合详情请看：http://www.tpyyes.com/a/javaweb/2016/1103/23.html
1.首先我们创建一个测试用的jsp页面，代码如下。
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<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>文件上传下载</title> </head> <body> <form action="http://localhost:8080/uploadDemo/rest/file/upload" method="post" enctype="multipart/form-data"> 选择文件:<input type="file" name="file" width="120px"> <input type="submit" value="上传"> </form> <hr> <form action="http://localhost:8080/uploadDemo/rest/file/down" method="get"> <input type="submit" value="下载"> </form> </body> </html>2.在我们的maven项目的pom.xml文件中添加fileupload文件上传下载jar包，不然后面的操作可能会报错，如下。
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<!-- 文件上传 --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3</version> </dependency>3.在spring的servlet视图解析器下面定义CommonsMultipartResolver文件解析器，就是加入这个的时候运行项目，如果没有fileuload相关的jar包就会报错。
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<!-- 定义文件解释器 --> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <!-- 设置默认编码 --> <property name="defaultEncoding" value="utf-8"></property> <!-- 上传图片最大大小5M--> <property name="maxUploadSize" value="5242440"></property> </bean>4.在controller层写上springmvc上传下载的代码，如下。
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package com.baidu; @RequestMapping("file") @Controller public class FileController { /** * 文件上传功能 * @param file * @return * @throws IOException */ @RequestMapping(value="/upload",method=RequestMethod.POST) @ResponseBody public String upload(MultipartFile file,HttpServletRequest request) throws IOException{ String path = request.getSession().getServletContext().getRealPath("upload"); String fileName = file.getOriginalFilename(); File dir = new File(path,fileName); if(!dir.exists()){ dir.mkdirs(); } //MultipartFile自带的解析方法 file.transferTo(dir); return "ok!"; } /** * 文件下载功能 * @param request * @param response * @throws Exception */ @RequestMapping("/down") public void down(HttpServletRequest request,HttpServletResponse response) throws Exception{ //模拟文件，myfile.txt为需要下载的文件 String fileName = request.getSession().getServletContext().getRealPath("upload")+"/myfile.txt"; //获取输入流 InputStream bis = new BufferedInputStream(new FileInputStream(new File(fileName))); //假如以中文名下载的话 String filename = "下载文件.txt"; //转码，免得文件名中文乱码 filename = URLEncoder.encode(filename,"UTF-8"); //设置文件下载头 response.addHeader("Content-Disposition", "attachment;filename=" + filename); //1.设置文件ContentType类型，这样设置，会自动判断下载文件类型 response.setContentType("multipart/form-data"); BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream()); int len = 0; while((len = bis.read()) != -1){ out.write(len); out.flush(); } out.close(); } }springmvc上传下载很方便，代码直接复制使用。
