spring-boot上传文件MultiPartFile获取不到文件问题解决
1.现象是在spring-boot里加入 commons-fileupload jar并且配置了mutilPart的bean,在upload的POST请求后,发现
multipartRequest.getFiles("file")=null,有点奇怪,查了文档资料才解决。
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="104857600"/>
<property name="maxInMemorySize" value="4096"/>
</bean>
2.原因是:spring-boot自带的org.springframework.web.multipart.MultipartFile
和Multipart产生冲突,如果同时使用了MultipartResolver 和ServletFileUpload,就会在iter.hasNext()返回false.然后整个循环就跳出去了。整个问题产生的原因是Spring框架先调用了MultipartResolver 来处理http multi-part的请求。这里http multipart的请求已经消耗掉。后面又交给ServletFileUpload ,那么ServletFileUpload 就获取不到相应的multi-part请求。因此将multipartResolve配置去除,问题就解决了。
3. 单文件的话只需要一个变量即,多文件上传的话就将MultipartFile改为数组,然后分别上传保存即可。
@RequestMapping(value="/multipleSave", method=RequestMethod.POST ) public @ResponseBody String multipleSave(@RequestParam("file") MultipartFile[] files){ String fileName = null; String msg = ""; if (files != null && files.length >0) { for(int i =0 ;i< files.length; i++){ try { fileName = files[i].getOriginalFilename(); byte[] bytes = files[i].getBytes(); BufferedOutputStream buffStream = new BufferedOutputStream(new FileOutputStream(new File("/tmp/" + fileName))); buffStream.write(bytes); buffStream.close(); msg += "You have successfully uploaded " + fileName"; } catch (Exception e) { return "You failed to upload " + fileName + ": " + e.getMessage(); } } return msg; } else { return "Unable to upload. File is empty."; } } }
4.spring-boot 配置上传文件和请求文件的最大值限制:
直接在application.properties中
multipart.maxFileSize=128KB
multipart.maxRequestSize=128KB
5. spring-boot-starter-web are already added as dependencies. To upload files with Servlet containers, you need to register aMultipartConfigElement class (which would be <multipart-config> in web.xml). Thanks to Spring Boot, everything is auto-configured for you! spring-boot-upload链接