我已经创建了一个签名的applet，用于将文件上传到服务器。代码运行良好，但是我想将该文件从applet发送到服务器端控制器，在该代码中，该控制器已将文件保存到服务器。

我的已签名Applet中的SendFile代码：

public static void sendFile(String destFileName) throws IOException {       
        String filePrivacy = "Public";
        String fileKeyword = "uploadFileDocumentName";
        String fileComments = "fileComments";
        String fileType = "txt";
        String fileFolder = "/Works";
        String fileDetails = "";
        HttpClient client = new HttpClient();
        PostMethod postMethod = new PostMethod(
                "http://localhost:8080/fileUpload/encryptFileUpload.works?filePrivacy="+filePrivacy+"&fileKeyword="+fileKeyword+"&fileComments="+fileComments+"&fileType="+fileType+"&fileFolder="+fileFolder+"&fileDetails="+fileDetails);

        File f = new File(destFileName);
        Part[] parts = {new FilePart(f.getName(), f)};
        postMethod.setRequestEntity(new MultipartRequestEntity(parts, postMethod.getParams())); 
        postMethod.setRequestHeader("Content-type", "text/xml; charset=ISO-8859-1");
        client.executeMethod(postMethod);
        postMethod.releaseConnection();
    }

我的UploadController的方法如下所示：

@RequestMapping(value = "/encryptFileUpload.works")
    public String uploadEncryptFile(String filePrivacy,
            String fileKeyword,
            String fileComments,
            String fileType,
            String fileFolder,
            HttpServletRequest request, HttpServletResponse response) {
        try {
            Map<String, Object> requestMap = new HashMap<String, Object>();
            requestMap.put(DMSConstants.JCR_FILE_PRIVACY, filePrivacy);
            requestMap.put(DMSConstants.JCR_FILE_KEYWORD, fileKeyword);
            requestMap.put(DMSConstants.JCR_FILE_COMMENTS, fileComments);
            requestMap.put(DMSConstants.JCR_FILE_TYPE, fileType);
            MultipartHttpServletRequest m = (MultipartHttpServletRequest) request;
            MultipartFile file = m.getFile("Filedata");
            Node folderNode = contentPublishService.getFolderNode(fileFolder);
            Node node = contentPublishService.saveFileToRepository(folderNode,
                    file.getInputStream(), file.getOriginalFilename(),
                    requestMap);
        } catch (RepositoryException e) {
            e.printStackTrace();        
        return null;
    }

在行上，MultipartHttpServletRequest m = (MultipartHttpServletRequest) request;我得到异常，如：

java.lang.ClassCastException: org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestWrapper cannot be cast to org.springframework.web.multipart.MultipartHttpServletRequest
    at com.nmmc.works.web.controller.FileUploadController.uploadEncryptFile(FileUploadController.java:177)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)

所以哪里出了问题，我应该在代码中进行哪些更改。第二件事是谁可以向控制器获取文件？