附件上传下载总结

1.数据库炫耀两张表，SYS_ATTACHMENT（存放附件内容）和SYS_ATTACHMENTBUSINESSRELATION（存放附件和业务内容相关）。定义如下：

create table SYS_ATTACHMENT
(
  eventid         VARCHAR2(50),
  filename        VARCHAR2(50),
  filetype        VARCHAR2(50),
  filesize        NUMBER(12),
  content         BLOB,
  filedescription VARCHAR2(200),
  fileurl         VARCHAR2(500),
  createby        VARCHAR2(50),
  createddate     DATE,
  lastmodifyby    VARCHAR2(50),
  lastmodifydate  DATE,
  status          NUMBER(4)
)

create table SYS_ATTACHMENTBUSINESSRELATION
(
  attachmentid      VARCHAR2(50),
  businessdateid    VARCHAR2(50),
  businessdatetable VARCHAR2(50)
)

2.附件下载，附件内容存在Blob字段内。

主要方法：

  /**
	 * 
	 *@User   :Test
	 *@date   :2014-6-4 上午10:18:55
	 *@return :void
	 *@userFor :用于附件下载
	 */
	public void downloadAttachement(HttpServletRequest request, HttpServletResponse response)
	{
		//得到业务id
		String eventid = request.getParameter("eventid");
		Attachment attachmentEntity = xxService.getAttachement(eventid);
		//获得附件内容Blob
		Blob blob = attachmentEntity.getcontent();
		try
		{
			InputStream inputstream = null;
			byte filedata[] = null ;
			if (blob != null)
			{
				inputstream = blob.getBinaryStream();
				//获得字节数组
				filedata = new byte[inputstream.available()];
			}
			String fileNameMid = "";
			//处理中文乱码问题
			fileNameMid = URLEncoder.encode(attachmentEntity.getfilename(), "utf-8");
			//把+号转空格  %20是空格意思
			fileNameMid = fileNameMid.replace("+", "%20");
			//用于页面跳出下载提示
			response.setHeader("Content-Disposition", (new StringBuilder("attachment;filename=")).append(fileNameMid).toString());
			OutputStream outS = response.getOutputStream();
                        //下载到本地
			outS.write(filedata);
			
			inputstream.close();
			response.getOutputStream().flush();
			response.getOutputStream().close();
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}

3.附件上传
采用的附件上传插件是ServletFileUpload，jar包是commons-fileupload-1.2.2.jar
Spring MVC对应的Controller方法是

public Map<String, Object> saveWaterSoil(MultipartHttpServletRequest request, xx entity)

 /**
	 * 
	 *@User   :Test
	 *@date   :2014-6-4 上午11:15:59
	 *@return :List<AttachmentBo>
	 *@userFor :从MultipartHttpServletRequest中获得附件集合
	 */
    public List<AttachmentBo> getAttachmentBoList(MultipartHttpServletRequest request)
    {
    	
    	 List<AttachmentBo> attachmentBoList = new ArrayList<AttachmentBo>();
    	 /**
 		 * 为该请求创建一个DiskFileItemFactory对象，
 		 * 通过它来解析请求。执行解析后，所有的表单项目都
 		 * 保存在一个List中。
 		 */
         DiskFileItemFactory factory = new DiskFileItemFactory();
         //设置缓冲区
         factory.setSizeThreshold(102400000);
         ServletFileUpload upload = new ServletFileUpload(factory);
         //设置附件上传大小
         upload.setSizeMax(102400000);
         upload.setHeaderEncoding("UTF-8");
         HttpSession session = request.getSession();
         String username = (String) session.getAttribute("user");
         if (!upload.isMultipartContent(request))
         {
             return null;
         }
         try
         {
        	 Map<String, MultipartFile> multipartFileMap=request.getFileMap();
        	 Set<String> keySet=multipartFileMap.keySet();
        	 for (String key : keySet) {
        		 AttachmentBo m_AttachmentBo = new AttachmentBo();
        		 MultipartFile multipartFile=multipartFileMap.get(key);
        		 String fileName=multipartFile.getOriginalFilename();
        		 m_AttachmentBo.setfilesize(Integer.parseInt(multipartFile.getSize() + ""));
        		 //获得附件内容
                 m_AttachmentBo.setcontent(Hibernate.createBlob(multipartFile.getBytes()));
                 m_AttachmentBo.setcreateby(username);
                 m_AttachmentBo.setlastmodifyby(username);
                 m_AttachmentBo.setfilename(fileName);
                 m_AttachmentBo.setfilesize(Integer.parseInt(((Long)multipartFile.getSize()).toString()));
                 String desc=request.getParameter(key.concat("desc"));
                 m_AttachmentBo.setfiledescription(desc);
                 attachmentBoList.add(m_AttachmentBo);
			}
        	 return attachmentBoList;
         }
         catch (Exception e)
         {
        	 e.printStackTrace();
             return null;
         }
    }