upload.parseRequest为空

FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setHeaderEncoding("UTF-8");
List items = upload.parseRequest(request);

转载:http://blog.csdn.net/happywzc110/article/details/7819037

上传是items一直是空list。导致原因是struts2把原始的原来S2为简化上传功能，把所有的enctype="multipart/form-data"表单做了wrapper最后把HttpServletResquest封装成 org.apache.struts2.dispatcher.multipart.MultiPartRequestWrapper 怪不得我的 ServletFileUpload.parseRequest(request)不行！！！ 

看我怎么改！废话不多说，直接贴代码！

MultiPartRequestWrapper wrapper = (MultiPartRequestWrapper) request;
        File file = wrapper.getFiles("imgFile")[0];
        String fileName = wrapper.getFileNames("imgFile")[0];
        //检查文件大小
        if(file.length() > maxSize){
            String temStr= "上传文件大小超过限制。";
            this.writeResponse(response, temStr);
            return;
        }
        //检查扩展名
        String fileExt = fileName.substring(fileName.lastIndexOf(".") + 1).toLowerCase();
        if(!Arrays.<String>asList(extMap.get(dirName).split(",")).contains(fileExt)){
            String temStr= "上传文件扩展名是不允许的扩展名。\n只允许" + extMap.get(dirName) + "格式。";
            this.writeResponse(response, temStr);
            return;
        }

        SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");
        String newFileName = df.format(new Date()) + "_" + new Random().nextInt(1000) + "." + fileExt;

        try {
            InputStream in = new FileInputStream(file);
            File uploadFile = new File(savePath, newFileName);
            OutputStream out = new FileOutputStream(uploadFile);
            byte[] buffer = new byte[1024 * 1024];
            int length;
            while ((length = in.read(buffer)) > 0) {
                out.write(buffer, 0, length);
            }

            in.close();
            out.close();
        } catch (FileNotFoundException ex) {
            ex.printStackTrace();
        } catch (IOException ex) {
            ex.printStackTrace();
        }