C/C++教程

解决MultipartFile.transferTo(dest) 报FileNotFoundExcep的问题

本文主要是介绍解决MultipartFile.transferTo(dest) 报FileNotFoundExcep的问题,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
这篇文章主要介绍了解决MultipartFile.transferTo(dest) 报FileNotFoundExcep的问题,具有很好的参考价值,希望对大家有所帮助。如有错误或未考虑完全的地方,望不吝赐教  

Spring Upload file 报错FileNotFoundException

环境:

  • Springboot 2.0.4
  • JDK8
  • 内嵌 Apache Tomcat/8.5.32

表单,enctype 和 input 的type=file 即可,例子使用单文件上传

1 2 3 4 5 <form enctype="multipart/form-data" method="POST"  action="/file/fileUpload">  图片<input type="file" name="file" />  <input type="submit" value="上传" /> </form>
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 @Controller @RequestMapping("/file") public class UploadFileController {     @Value("${file.upload.path}")     private String path = "upload/";       @RequestMapping(value = "fileUpload", method = RequestMethod.POST)     @ResponseBody     public String fileUpload(@RequestParam("file") MultipartFile file) {         if (file.isEmpty()) {             return "false";         }         String fileName = file.getOriginalFilename();         File dest = new File(path + "/" + fileName);         if (!dest.getParentFile().exists()) {             dest.getParentFile().mkdirs();         }         try {             file.transferTo(dest); // 保存文件             return "true";         } catch (Exception e) {             e.printStackTrace();             return "false";         }     } }

运行在保存文件 file.transferTo(dest) 报错

问题

dest 是相对路径,指向 upload/doc20170816162034_001.jpg

file.transferTo 方法调用时,判断如果是相对路径,则使用temp目录,为父目录

因此,实际保存位置为 C:\Users\xxxx\AppData\Local\Temp\tomcat.372873030384525225.8080\work\Tomcat\localhost\ROOT\upload\doc20170816162034_001.jpg

一则,位置不对,二则没有父目录存在,因此产生上述错误。

解决办法

transferTo 传入参数 定义为绝对路径

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 @Controller @RequestMapping("/file") public class UploadFileController {     @Value("${file.upload.path}")     private String path = "upload/";       @RequestMapping(value = "fileUpload", method = RequestMethod.POST)     @ResponseBody     public String fileUpload(@RequestParam("file") MultipartFile file) {         if (file.isEmpty()) {             return "false";         }         String fileName = file.getOriginalFilename();         File dest = new File(new File(path).getAbsolutePath()+ "/" + fileName);         if (!dest.getParentFile().exists()) {             dest.getParentFile().mkdirs();         }         try {             file.transferTo(dest); // 保存文件             return "true";         } catch (Exception e) {             e.printStackTrace();             return "false";         }     } }

另外也可以 file.getBytes() 获得字节数组,OutputStream.write(byte[] bytes)自己写到输出流中。

补充方法

application.properties 中增加配置项

1 spring.servlet.multipart.location= # Intermediate location of uploaded files.

关于上传文件的访问

1、增加一个自定义的ResourceHandler把目录公布出去

1 2 3 4 5 6 7 8 9 10 11 12 13 14 // 写一个Java Config @Configuration public class webMvcConfig implements org.springframework.web.servlet.config.annotation.WebMvcConfigurer{     // 定义在application.properties     @Value("${file.upload.path}")     private String path = "upload/";     public void addResourceHandlers(ResourceHandlerRegistry registry) {         String p = new File(path).getAbsolutePath() + File.separator;//取得在服务器中的绝对路径         System.out.println("Mapping /upload/** from " + p);         registry.addResourceHandler("/upload/**") // 外部访问地址             .addResourceLocations("file:" + p)// springboot需要增加file协议前缀             .setCacheControl(CacheControl.maxAge(30, TimeUnit.MINUTES));// 设置浏览器缓存30分钟     } }    

application.properties 中 file.upload.path=upload/

实际存储目录

D:/upload/2019/03081625111.jpg

访问地址(假设应用发布在http://www.a.com/)

http://www.a.com/upload/2019/03081625111.jpg

2、在Controller中增加一个RequestMapping,把文件输出到输出流中

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 @RestController @RequestMapping("/file") public class UploadFileController {     @Autowired     protected HttpServletRequest request;     @Autowired     protected HttpServletResponse response;     @Autowired     protected ConversionService conversionService;       @Value("${file.upload.path}")     private String path = "upload/";          @RequestMapping(value="/view", method = RequestMethod.GET)     public Object view(@RequestParam("id") Integer id){         // 通常上传的文件会有一个数据表来存储,这里返回的id是记录id         UploadFile file = conversionService.convert(id, UploadFile.class);// 这步也可以写在请求参数中         if(file==null){             throw new RuntimeException("没有文件");         }                   File source= new File(new File(path).getAbsolutePath()+ "/" + file.getPath());         response.setContentType(contentType);           try {             FileCopyUtils.copy(new FileInputStream(source), response.getOutputStream());         } catch (Exception e) {             e.printStackTrace();         }         return null;     } }

MultipartFile.transferTo(dest) 报找不到文件

今天使用transferTo这个方法进行上传文件的使用发现了一些路径的一些问题,查找了一下记录问题所在

前端上传网页,使用的是单文件上传的方式

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 <!DOCTYPE html> <html lang="en"> <head>     <meta charset="UTF-8">     <title>Title</title>     <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> </head> <body>     <form enctype="multipart/form-data" method="post" action="/upload">         文件:<input type="file" name="head_img">         姓名:<input type="text" name="name">         <input type="submit" value="上传">     </form> </body> </html>

后台网页

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 @Controller @RequestMapping("/file") public class UploadFileController {     @Value("${file.upload.path}")     private String path = "upload/";     @RequestMapping(value = "fileUpload", method = RequestMethod.POST)     @ResponseBody     public String fileUpload(@RequestParam("file") MultipartFile file) {         if (file.isEmpty()) {             return "false";         }         String fileName = file.getOriginalFilename();         File dest = new File(path + "/" + fileName);         if (!dest.getParentFile().exists()) {             dest.getParentFile().mkdirs();         }         try {             file.transferTo(dest); // 保存文件             return "true";         } catch (Exception e) {             e.printStackTrace();             return "false";         }     } }

这个确实存在一些问题

路径是不对的

dest 是相对路径,指向 upload/doc20170816162034_001.jpg

file.transferTo 方法调用时,判断如果是相对路径,则使用temp目录,为父目录

因此,实际保存位置为 C:\Users\xxxx\AppData\Local\Temp\tomcat.372873030384525225.8080\work\Tomcat\localhost\ROOT\upload\doc20170816162034_001.jpg

所以改为:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 @Controller @RequestMapping("/file") public class UploadFileController {     @Value("${file.upload.path}")     private String path = "upload/";     @RequestMapping(value = "fileUpload", method = RequestMethod.POST)     @ResponseBody     public String fileUpload(@RequestParam("file") MultipartFile file) {         if (file.isEmpty()) {             return "false";         }         String fileName = file.getOriginalFilename();         File dest = new File(new File(path).getAbsolutePath()+ "/" + fileName);         if (!dest.getParentFile().exists()) {             dest.getParentFile().mkdirs();         }         try {             file.transferTo(dest); // 保存文件             return "true";         } catch (Exception e) {             e.printStackTrace();             return "false";         }     } }
 转自:https://www.jb51.net/article/216452.htm
这篇关于解决MultipartFile.transferTo(dest) 报FileNotFoundExcep的问题的文章就介绍到这儿,希望我们推荐的文章对大家有所帮助,也希望大家多多支持为之网!