javaweb项目中的文件上传下载功能的实现

<form action="${ctx}/file/upLoadFile.do"method="post" enctype="multipart/form-data" id="form"><table><tbody ><tr ><td>上传文件:</td><td style="padding-left: 10px;"><input type="file" name="file" id="fileInput"></td><td style="padding-left: 80px;"><button type="submit" class="btn btn-primary btn-q btn-outline fa fa-upload"

 class="easyui-validatebox" data-options="required:true">上传</button></td></tr><tr><td colspan="2"><span style="color:red">*上传文件格式为xls,xlsx,txt,csv文件!</span>&nbsp;&nbsp;</td>

</tr>

</tbody>

</table></form>

{

  title : '操作',

  halign : 'center',

  align : 'center',

  width : 80,

  field : 'FILE_PATH',

  formatter: function(value,row,index){

  var path = "${ctx}/file/download.do?filePath=" + value ;

  var button = '<button type="button" class="btn btn-primary btn-q btn-outline fa fa-download" class="easyui-validatebox" 

           data-options="required:true">下载</button>';

          return "<a href='" + path  + "'>" + button +  "</a>";

}

@RequestMapping("/upLoadFile")

    public String upload(@RequestParam(value = "file", required = false) MultipartFile file, ModelMap model, HttpServletRequest request) 

throws Exception {

//设置相对路径

        String realPath = request.getSession().getServletContext().getRealPath("/upload");

//获取文件的格式

        String extention = file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf(".")+1);

//对格式进行筛选

        if(extention.equalsIgnoreCase("xls") || extention.equalsIgnoreCase("xlsx") || extention.equalsIgnoreCase("txt") 

|| extention.equalsIgnoreCase("csv")) {

//在路径下创建文件夹

  File f = new File(realPath);

            String fileName = file.getOriginalFilename();

            String uploadPath = realPath + File.separator + fileName;

            if(!f.exists()) {

                f.mkdir();

            }

//文件的传输

            file.transferTo(new File(uploadPath));

            Upload upload = new Upload();

            upload.setFileName(fileName);

            upload.setFileLength(String.valueOf(file.getSize()));

            upload.setFileOwner(super.getLoginUser(request).getLoginId());

            upload.setFilePath("/upload/" + fileName);

//将文件的基本信息存到数据库

            fileQueryService.saveFile(upload);

            request.setAttribute("info","文件上传成功!");

        } else {

            request.setAttribute("info","文件类型不正确，请上传格式为xls,xlsx,txt,csv文件!");

        }

        return "page/file/fileInteraction";

    }

@RequestMapping("/download")

    public String download(String filePath, HttpServletRequest request,

                           HttpServletResponse response) {

        try {

//获取文件名

            String fileName = filePath.substring(filePath.lastIndexOf("/")+1);

            System.out.println(filePath);

            response.setCharacterEncoding("utf-8");

            response.setContentType("multipart/form-data");

//处理下载弹出框名字的编码问题

            response.setHeader("Content-Disposition", "attachment;fileName="

                    + new String( fileName.getBytes("gb2312"), "ISO8859-1" ));

//获取文件的下载路径

            String path = request.getSession().getServletContext().getRealPath(filePath);

            System.out.println(path);

//利用输入输出流对文件进行下载

            InputStream inputStream = new FileInputStream(new File(path));

            OutputStream os = response.getOutputStream();

            byte[] b = new byte[2048];

            int length;

            while ((length = inputStream.read(b)) > 0) {

                os.write(b, 0, length);

            }

            // 这里主要关闭。

            os.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

        //  返回值要注意，要不然就出现下面这句错误！

        //java+getOutputStream() has already been called for this response

        return null;

    }