<bean id="multipartResolver"
          class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
          <description>
                  ifpre::要使用文件上传功能，必须在定义文件中加入MeltipartResolver,
                  可以选用CommonsMutipartResolver或CosMultipartResolver
          </description>
        <property name="maxUploadSize">
            <value>1000000</value>
        </property>
    </bean>

写完后调试的过程中，老报错：java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream，少了commons-io.jar，加上后，就ok了

在Controller端，可以用以下方式取得上传的文件，可以上传多个文件：
 public Set getMultipartFileForForm(HttpServletRequest req) {
  MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) req;
  // CommonsMultipartFile file = (CommonsMultipartFile)
  // multipartRequest.getFile("attach");//attach为form为file的id值
  // MultipartHttpServletRequest multipartRequest =
  // (MultipartHttpServletRequest)request;
  Set fileset = new LinkedHashSet();
  for (Iterator it = multipartRequest.getFileNames(); it.hasNext();) {
   String key = (String) it.next();
   MultipartFile file = multipartRequest.getFile(key);
   if (file.getOriginalFilename().length() > 0) {
    fileset.add(file);
   }
  }
  return fileset;
 }