spring mvc实现文件上传与下载功能

  <!-- spring mvc -->
  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-webmvc</artifactId>
   <version>4.3.13.RELEASE</version>
  </dependency>
  
  <!-- 文件上传与下载 -->
  <dependency>
   <groupId>commons-fileupload</groupId>
   <artifactId>commons-fileupload</artifactId>
   <version>1.3.3</version>
  </dependency>

 <bean id="multipartResolver" 
  class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 
  <!-- 上传文件大小上限，单位为字节（10MB） -->
  <property name="maxUploadSize"> 
   <value>10485760</value> 
  </property> 
  <!-- 请求的编码格式，必须和jSP的pageEncoding属性一致，以便正确读取表单的内容，默认为ISO-8859-1 -->
  <property name="defaultEncoding">
   <value>UTF-8</value>
  </property>
 </bean>

<form action="upload" enctype="multipart/form-data" method="post">
 <table>
  <tr>
   <td>文件描述:</td>
   <td><input type="text" name="description"></td>
  </tr>
  <tr>
   <td>请选择文件:</td>
   <td><input type="file" name="file"></td>
  </tr>
  <tr>
   <td><input type="submit" value="上传"></td>
  </tr>
 </table>
</form>

//上传文件会自动绑定到MultipartFile中
@RequestMapping(value="/upload",method=RequestMethod.POST)
public String upload(HttpServletRequest request,
  @RequestParam("description") String description,
  @RequestParam("file") MultipartFile file) throws Exception {
 
 //如果文件不为空，写入上传路径
 if(!file.isEmpty()) {
  //上传文件路径
  String path = request.getServletContext().getRealPath("/file/");
  //上传文件名
  String filename = file.getOriginalFilename();
  File filepath = new File(path,filename);
  //判断路径是否存在，如果不存在就创建一个
  if (!filepath.getParentFile().exists()) {
   filepath.getParentFile().mkdirs();
  }
  //将上传文件保存到一个目标文件当中
  file.transferTo(new File(path + File.separator + filename));
  return "success";
 } else {
  return "error";
 }
 
}