springMVC后台如何接受前端上传的文件，与及下载文件

public static Map<String, Object> upload(HttpServletRequest request) throws IOException{
//文件上传的请求
MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) request;
//获取请求的参数
Map<String, MultipartFile> fileMap = mRequest.getFileMap();
//项目的绝对路径   request.getSession().getServletContext().getRealPath()这个是得到项目的绝对地址
String ctxPath = request.getSession().getServletContext().getRealPath("/")
+ FileOperateUtil.FILEDIR;
File file = new File(ctxPath);
if (!file.exists()) {
file.mkdir();
}
Map<String, Object> result = new HashMap<String, Object>();
Iterator<Map.Entry<String, MultipartFile>> it = fileMap.entrySet().iterator();
//用hasNext() 判断是否有值，用next()方法把元素取出。
while(it.hasNext()){
Map.Entry<String, MultipartFile> entry = it.next();
MultipartFile mFile = entry.getValue();
if(mFile.getSize() != 0 && !"".equals(mFile.getName())){
write(mFile.getInputStream(), new FileOutputStream(ctxPath+mFile.getOriginalFilename()));
result.put(mFile.getName(), mFile.getOriginalFilename());
}
}

return result;
}

public static void download(HttpServletRequest request,
HttpServletResponse response, String storeName, String contentType,
String realName) throws Exception {
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("UTF-8");
BufferedInputStream bis = null;
BufferedOutputStream bos = null;

String ctxPath = request.getSession().getServletContext()
.getRealPath("/")
+ "你的存储的地址";
String downLoadPath = ctxPath + storeName;

long fileLength = new File(downLoadPath).length();

response.setContentType(contentType);
response.setHeader("Content-disposition", "attachment; filename="
+ new String(realName.getBytes("utf-8"), "ISO8859-1"));
response.setHeader("Content-Length", String.valueOf(fileLength));

bis = new BufferedInputStream(new FileInputStream(downLoadPath));
bos = new BufferedOutputStream(response.getOutputStream());
byte[] buff = new byte[2048];
int bytesRead;
while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
bos.write(buff, 0, bytesRead);
}
bis.close();
bos.close();
}