解决request.getSession().getServletContext().getRealPath("/")为null问题

我们使用了request.getSession().getServletContext().getRealPath()方法将虚拟路径转换为物理路径。这个方法返回的是服务器上的物理路径，然后我们如何使用Java IO API读取文件内容了。

BufferedInputStream bis = null; BufferedOutputStream bos = null; String downLoadPath = request.getSession().getServletContext().getRealPath("/uploads/") + fileName; ; //注意不同系统的分隔符 // String downLoadPath =filePath.replaceAll("/", "\\\\\\\\"); //replace replaceAll区别 ***** System.out.println("downLoadPath=" + downLoadPath);请详细解释每一行代码

@RequestMapping("/addAppliance") //接口路径 public String addAppliance(@RequestBody Appliance appliance,HttpSession session,Model model,HttpServletRequest request, HttpServletResponse response){ //传递的参数是家电实体 Seller seller = (Seller) session.getAttribute("seller"); if (seller == null) { //如果卖家没有登录 request.setAttribute("error","请先登陆后再上架家电");return "login";} Stringpn=Pic.gainPicture(appliance.getAppliancepicture(),"D:/secondhandHA/src/ main/webapp/img/",request.getSession().getServletContext().getRealPath("/img/")); appliance.setAppliancepicture("img/"+pn); //获取二手家电图片 appliance.setSellerid(seller.getSellerid()); //获取卖家id appliance.setApplianceid(UuidUtils.getUuid()); //调用UuidUtils工具类设置家电id int rows = applianceService.addAppce(appliance); //调用applianceService中的addAppce将此家电添加到数据库中并且返回受影响的行数 if(rows > 0){ request.setAttribute("success","上架家电成功");return "appliancesl";}else{ request.setAttribute("error","上架家电失败，请重试");return "addapp";}} //判断上架家电是否成功

@RequestMapping(value = "/image.action") public String upload( @RequestParam(value ="image", required = false) MultipartFile file, @RequestParam(value ="image1", required = false) MultipartFile file1, HttpServletRequest request, ModelMap model) { String path = request.getSession().getServletContext().getRealPath("/") + "upfiles/"; String fileName = file.getOriginalFilename(); int i = fileName.lastIndexOf("."); String name = String.valueOf(VeDate.getStringDatex()); String type = fileName.substring(i + 1); fileName = name + "." + type; File targetFile = new File(path, fileName); if (!targetFile.exists()) { targetFile.mkdirs(); } // 保存第一张图片 try { file.transferTo(targetFile); } catch (Exception e) { e.printStackTrace(); } // 保存第二张图片 String fileName1 = file1.getOriginalFilename(); int j = fileName1.lastIndexOf("."); String name1 = String.valueOf(VeDate.getStringDatex()); String type1 = fileName1.substring(j + 1); fileName1 = name1 + "." + type1; File targetFile1 = new File(path, fileName1); if (!targetFile1.exists()) { targetFile1.mkdirs(); } try { file1.transferTo(targetFile1); } catch (Exception e) { e.printStackTrace(); } model.addAttribute("imageFileName", fileName); model.addAttribute("image1FileName", fileName1); return "page/saveimage"; }如何添加判断空指针异常的代码