File upload progress in spring boot

Question

To upload a file in spring boot one can use something like this:

@PostMapping("/")
public String handleFileUpload(@RequestParam("file") MultipartFile file,
    RedirectAttributes redirectAttributes) {

    storageService.store(file);
    redirectAttributes.addFlashAttribute("message",
        "You successfully uploaded " + file.getOriginalFilename() + "!");

    return "redirect:/";
}

and it works fine.

My problem is how can I extend this code to get some kind of updates during upload. For example: one enent every 10% of completed upload. Is there any kind of mechanism which creates such events during upload? Can I overwrite some internal spring method to make it work?

Answer 1

要获取进度更新回调，请将以下 bean 添加到您的应用程序中：

@Bean(name = "multipartResolver")
public CommonsMultipartResolver createMultipartResolver() {

  final CommonsMultipartResolver cmr = new CommonsMultipartResolver();

  cmr.setMaxUploadSize(10000000); // customize as appropriate
  cmr.setDefaultEncoding("UTF-8");  // important to match in your client
  cmr.getFileUpload().setProgressListener(
      (long pBytesRead, long pContentLength, int pItems) -> {
        // insert progress update logic here
      });

  return cmr;
}

还将以下属性添加到您的应用程序属性中：

spring.http.multipart.enabled = false

UTF-8注意：您的客户端应用程序与预期的内容编码相匹配（在本示例中）非常重要。如果没有，那么FileUpload将使用一个临时对象，而不是我们在上面代码中自定义的对象。这可能是一个错误，CommonsFileUploadSupport.java因为它将原始的所有其他成员复制FileUpload到临时成员中，忽略了侦听器。