HttpServletRequest 获取multipartFile

HttpServletRequest 中获取 MultipartFile 的方法是通过 getInputStream() 方法获取文件流，然后通过 MultipartFile 的构造函数将文件流转换为 MultipartFile 对象。具体代码如下：

@RequestMapping(value = "/upload", method = RequestMethod.POST)
public String upload(HttpServletRequest request) throws IOException {
    MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
    MultipartFile file = multipartRequest.getFile("file");
    InputStream inputStream = file.getInputStream();
    // ...
}

注意：这里的 "file" 是表单中文件上传控件的 name 属性值。