Spring Upload File 报错FileNotFoundException
环境: Springboot 2.0.4 JDK1.8 内嵌 Apache Tomcat/8.5.32
1、前端代码
前端上传网页表单,enctype 和 input 的type=file 即可,使用单文件上传举例:
<form enctype="multipart/form-data" method="POST" action="/file/fileUpload"> 图片<input type="file" name="file" /> <input type="submit" value="上传" /> form>
2、后端代码
@RestController @RequestMapping("/file") public class UploadFileController { @Value("${file.upload.path}") private String path = "upload/"; @RequestMapping(value = "fileUpload", method = RequestMethod.POST) @ResponseBody public String fileUpload(@RequestParam("file") MultipartFile file) { if (file.isEmpty()) { return "false"; } String fileName = file.getOriginalFilename(); File saveFile = new File(path + "/" + fileName); if (!saveFile.getParentFile().exists()) { saveFile.getParentFile().mkdirs(); } try { file.transferTo(saveFile); // 保存文件 return "true"; } catch (Exception e) { e.printStackTrace(); return "false"; } } }
3、问题分析与解决
按照上面配置运行时,在保存文件 file.transferTo(saveFile) 报错
3.1 问题原因分析:
saveFile是相对路径,指向 upload/doc20170816162034_001.jpg
file.transferTo 方法调用时,判断如果是相对路径,则使用temp目录,为父目录
因此,实际保存位置为 C:\Users\xxxx\AppData\Local\Temp\tomcat.372873030384525225.8080\work\Tomcat\localhost\ROOT\upload\doc20170816162034_001.jpg
一则,位置不对,二则没有父目录存在,因此产生上述错误。
3.2 问题解决
transferTo 传入参数 定义为绝对路径
@RestController @RequestMapping("/file") public class UploadFileController { @Value("${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"; } } }
也可以 file.getBytes() 获得字节数组,OutputStream.write(byte[] bytes)自己写到输出流中。
4、补充方法
application.properties 中增加配置项
spring.servlet.multipart.location= # Intermediate location of uploaded files.
关于上传文件的访问
增加一个自定义的ResourceHandler把目录公布出去
// 写一个Java Config @Configuration public class webMvcConfig implements org.springframework.web.servlet.config.annotation.WebMvcConfigurer{ // 定义在application.properties @Value("${file.upload.path}") private String path = "upload/"; public void addResourceHandlers(ResourceHandlerRegistry registry) { String p = new File(path).getAbsolutePath() + File.separator;//取得在服务器中的绝对路径 System.out.println("Mapping /upload/** from " + p); registry.addResourceHandler("/upload/**") // 外部访问地址 .addResourceLocations("file:" + p)// springboot需要增加file协议前缀 .setCacheControl(CacheControl.maxAge(30, TimeUnit.MINUTES));// 设置浏览器缓存30分钟 } }
application.properties 中 file.upload.path=upload/
实际存储目录
D:/upload/2019/03081625111.jpg
访问地址(假设应用发布在http://www.a.com/)
http://www.a.com/upload/2019/03081625111.jpg
在Controller中增加一个RequestMapping,把文件输出到输出流中
@RestController @RequestMapping("/file") public class UploadFileController { @Autowired protected HttpServletRequest request; @Autowired protected HttpServletResponse response; @Autowired protected ConversionService conversionService; @Value("${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; } }