@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"; }如何空指针异常错误，列出具体方法

在该代码中，可能会出现空指针异常的方法有：

1. file.getOriginalFilename()：如果file为null，则会抛出空指针异常。
2. file1.getOriginalFilename()：如果file1为null，则会抛出空指针异常。
3. targetFile.mkdirs()：如果创建目录失败，则会返回null，而如果在返回值上调用方法，会导致空指针异常。
4. file.transferTo(targetFile)：如果file为null或者targetFile为null，则会抛出空指针异常。
5. file1.transferTo(targetFile1)：如果file1为null或者targetFile1为null，则会抛出空指针异常。
6. model.addAttribute("imageFileName", fileName)：如果model为null，则会抛出空指针异常。
7. model.addAttribute("image1FileName", fileName1)：如果model为null，则会抛出空指针异常。

因此，在代码中应该加上空指针异常的判断，避免程序运行出现异常。

相关问题

@RequestMapping(value = "/image.action") //public String upload(@RequestParam(value ="image", required = false) MultipartFile file, HttpServletRequest request, ModelMap model) { 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 try { file.transferTo(targetFile); } catch (Exception e) { e.printStackTrace(); } model.addAttribute("imageFileName", fileName); return "page/saveimage"; }如何使image和image1有同样的效果

你可以将参数名改为相同的名称，这样在接收时就可以共用一个方法了，示例代码如下：

@RequestMapping(value = "/image.action")
public String upload(@RequestParam(value = "image", required = false) MultipartFile image, 
                     @RequestParam(value = "image", required = false) MultipartFile image1, 
                     HttpServletRequest request, ModelMap model) { 
    String path = request.getSession().getServletContext().getRealPath("/") + "upfiles/";     
    // 以下省略文件上传和保存的代码
    model.addAttribute("imageFileName", fileName);
    return "page/saveimage"; 
}

@RequestMapping(value = "/files.action") public String files( @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 try { file.transferTo(targetFile); } catch (Exception e) { e.printStackTrace(); } model.addAttribute("imageFileName", fileName); return "page/savefile"; }如何使参数image和image1有一样的效果

可以将@RequestParam(value ="image", required = false) MultipartFile file和@RequestParam(value ="image1", required = false) MultipartFile file1合并成一个@RequestParam(value ="file", required = false) MultipartFile[] files，然后在方法内部通过循环处理每一个文件。修改后的代码如下：

@RequestMapping(value = "/files.action")
public String files(@RequestParam(value ="file", required = false) MultipartFile[] files, HttpServletRequest request, ModelMap model) {
String path = request.getSession().getServletContext().getRealPath("/") + "upfiles/";
List<String> fileNames = new ArrayList<String>();
for(MultipartFile file: files){
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();
}
try {
file.transferTo(targetFile);
} catch (Exception e) {
e.printStackTrace();
}
fileNames.add(fileName);
}
model.addAttribute("imageFileNames", fileNames);
return "page/savefile";
}