1.現象是在spring-boot裏加入commons-fileupload jar並且配置了mutilPart的bean，在upload的POST請求後，發現

multipartRequest.getFiles("file")=null，有點奇怪，查了文檔資料才解決。

1. <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
2. <property name="maxUploadSize" value="104857600"/>
3. <property name="maxInMemorySize" value="4096"/>
4. </bean>

2.原因是：spring-boot自帶的org.springframework.web.multipart.MultipartFile
和Multipart產生沖突，如果同時使用了MultipartResolver 和ServletFileUpload，就會在iter.hasNext()返回false.然後整個循環就跳出去了。整個問題產生的原因是Spring框架先調用了MultipartResolver 來處理http multi-part的請求。這裏http multipart的請求已經消耗掉。後面又交給ServletFileUpload ，那麽ServletFileUpload 就獲取不到相應的multi-part請求。因此將multipartResolve配置去除，問題就解決了。

3. 單文件的話只需要一個變量即，多文件上傳的話就將MultipartFile改為數組，然後分別上傳保存即可。

1. @RequestMapping(value="/multipleSave", method=RequestMethod.POST )
2. public @ResponseBody String multipleSave(@RequestParam("file") MultipartFile[] files){
3. String fileName = null;
4. String msg = "";
5. if (files != null && files.length >0) {
6. for(int i =0 ;i< files.length; i++){
7. try {
8. fileName = files[i].getOriginalFilename();
9. byte[] bytes = files[i].getBytes();
10. BufferedOutputStream buffStream =
11. new BufferedOutputStream(new FileOutputStream(new File("/tmp/" + fileName)));
12. buffStream.write(bytes);
13. buffStream.close();
14. msg += "You have successfully uploaded " + fileName";
15. } catch (Exception e) {
16. return "You failed to upload " + fileName + ": " + e.getMessage();
17. }
18. }
19. return msg;
20. } else {
21. return "Unable to upload. File is empty.";
22. }
23. }
24. }

4.spring-boot 配置上傳文件和請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鏈接

spring-boot上傳文件MultiPartFile獲取不到文件問題解決