SSM框架的整合请看我之前的博客：http://www.cnblogs.com/1314wamm/p/6834266.html
现在我们先看如何编写文件的上传下载：你先看你的pom.xml中是否有文件上传的组件包
先看我们写的测试jsp页面：
<%@ 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>
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。
在controller层写上springmvc上传下载的代码
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();
}
}