<input type="file" name="pic"/>后台怎么获得file

看网上的回答说后台直接private File pic;加上get，set就可以得到file,
但是我得到的是String类型的图片名，请问后台如何得到前台选择的file图片

你是想获得上传的图片么？那应该在上传图片的函数里就能拿到你上传图片的路径，就可以找到了。
一开始还以为你要它的type属性呢，，，，，

我并没有单独写一个选择照片的方法，而是在jsp中使用，然后submit提交到后台，现在想的是在后台获取到file，或者是路径，
找到图片转成byte，插入到blob字段当中，但是不知道后台应该如何写（我是新手可能没有完全理解你的意思）

参考：

 https://q.cnblogs.com/q/28119/
https://zhidao.baidu.com/question/569710754.html?qbl=relate_question_0&word=jsp%D6%D0%CA%B9%D3%C3%3Cinput%20type%3D%22file%22%20name%3D%22pic%22/%3E

像这样的，uploadFileItem就是图片实体，通过uploadFileItem.getInputStream()获取文件流，in.read转成byte。

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //log.debug("------上传文件-----");
        CommonUtil.print("------上传文件-----");

        FileItem uploadFileItem = null;

        request.setCharacterEncoding("UTF-8");
        try {
            DiskFileItemFactory diskFactory = new DiskFileItemFactory();

            diskFactory.setSizeThreshold(1024 * 1024 * 1024);

            ServletFileUpload upload = new ServletFileUpload(diskFactory);

            upload.setSizeMax(1024 * 1024 * 1024);

            List<FileItem> fileItems = upload.parseRequest(new ServletRequestContext(request));
            Map<String, Object> params = new HashMap<String, Object>();
            for (Iterator<FileItem> iterator = fileItems.iterator(); iterator.hasNext();) {
                FileItem fileItem = iterator.next();
                if (fileItem.isFormField()) {
                    String name = fileItem.getFieldName();
                    String value = fileItem.getString();
                    params.put(name, parserStr(value));
                    //System.out.println(name + " = " + value);
                } else {
                    uploadFileItem = fileItem;
                }
            }

            String name = (String) params.get("shareId");

            String picId = CommonUtil.getUUID();

            String fileName = picId+"."
                    +this.getFileType(uploadFileItem.getName());
            String savePath = this.getServletContext().getRealPath("/share/images")+File.separator;

            //log.info("size:"+uploadFileItem.getSize());
            CommonUtil.print("size:"+uploadFileItem.getSize());
            String filepath = savePath+fileName;

            InputStream in = uploadFileItem.getInputStream();
            FileOutputStream out = new FileOutputStream(filepath);
            byte buffer[] = new byte[1024];
            int len = 0;
            while((len=in.read(buffer))>0){
               out.write(buffer, 0, len);
            }

            in.close();
            out.close();

            CommonUtil.print("---" +uploadFileItem.getName()+
                    "---上传文件成功-----");

            if(null != name ){
                Pic obj = new Pic(picId, filepath, name, this.getFileType(uploadFileItem.getName()));
                obj.setCurrentDate(new Date());
                ActionDao.getInstance().save(obj);

                CommonUtil.print("------已写入到数据库中---");
            }
            this.write(request, response, filepath, "", true);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

你可以用form进行提交后台 不过form 要加 enctype="multipart/form-data"