boolean flag = true;
        int length = getMyfileFileName().split("\\.").length;
        String docType = getMyfileFileName().split("\\.")[length - 1];// 文件类型
        try{//以下判断文件大小的
            FileInputStream fiss = new FileInputStream(myfile);
            String filesz = String.valueOf(fiss.available()/1000) ;//2000000k===2G
            if(Long.parseLong(filesz)>2000000l)
            {
                try {
                    response.getWriter().println("<script>alert('上传文件不能超过2G!');window.parent.location.reload();</script>");
                } catch (IOException e) {
                    e.printStackTrace();
                }
                return null ;
            }
        }catch(Exception e1){   
            System.out.println("我的文档上传出错！");
        }   
        // 以下才是正常的文件上传
        if (flag) {
            String currentTime = (new SimpleDateFormat("yyyyMMdd")) .format(new Date());// 把当前时间当成文件夹名字
            File dirFile = new File(ServletActionContext.getServletContext() .getRealPath("/")
                    + "upload\\document\\" + currentTime);
            if (!dirFile.exists()) {
                dirFile.mkdir();
            }
            String docTitle = request.getParameter("docTitle");// 文件名
            String docDescription = request.getParameter("docDescription");// 文件描述
            String docPath = "upload\\document\\" + currentTime + "\\" + getMyfileFileName();// 文件路径
            // 以服务器的文件保存地址和原文件名建立上传文件输出流
            File imageFile = new File(ServletActionContext
                    .getServletContext().getRealPath("/")
                    + "upload\\document\\"
                    + currentTime
                    + "\\"
                    + getMyfileFileName());
            copy(myfile, imageFile);
            
        
            FsDocument fd = new FsDocument();
            fd.setUserId(userId);// 用户ID-----现在是死的··以后还得动态得到当前用户
            fd.setDocType(docType);// 文档类型
            fd.setDocTitle(docTitle);// 文档标题
            fd.setDocPath(docPath);// 文档路径
            fd.setDocId(0l);// 文档ID
            fd.setDocDescription(docDescription);// 文档描述
            fd.setCreTime(new Date());// 创建时间
            documentService.saveData(fd);
        }

        try {
            response
                    .getWriter()
                    .println(
                            "<script>alert('文件上传成功!');window.parent.location.reload();</script>");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
    
    private  void copy(File src, File dst)  {
        try  {
           InputStream in = null ;
           OutputStream out = null ;
            try  {                
               in = new BufferedInputStream( new FileInputStream(src), BUFFER_SIZE);
               out = new BufferedOutputStream( new FileOutputStream(dst), BUFFER_SIZE);
                byte [] buffer = new byte [BUFFER_SIZE];
                while (in.read(buffer) > 0 )  {
                   out.write(buffer);
               } 
            } finally  {
                if ( null != in)  {
                   in.close();
               } 
                 if ( null != out)  {
                   out.close();
               } 
           } 
        } catch (Exception e)  {
           e.printStackTrace();
       } 
   }

------解决方案--------------------
Java code

public synchronized ActionForward add(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServle