参考博文地址 https://www.cnblogs.com/cplemom/p/11264040.html https://www.cnblogs.com/netcs/p/12789162.html
var client = _httpClientFactory.CreateClient();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue($"multipart/form-data"));
var content = new MultipartFormDataContent();
content.Add(new StringContent(type), "type");
byte[] arr;
using (Stream fileStream = file.OpenReadStream())
{
arr = new byte[fileStream.Length];
fileStream.Read(arr, 0, arr.Length);
}
var upFileContent = new ByteArrayContent(arr);
upFileContent.Headers.ContentType = new MediaTypeHeaderValue(file.ContentType);
content.Add(upFileContent, "file", file.FileName);
var reponse = await client.PostAsync("ip地址/api/FileUpload/ImageUpload", content);
主要还是橙色代码块 设置文件ContentType
不设置这个 接口端File.ContentType是接收不到类型的
HttpClient 上传文件带参数 ContentType 记录
原文：https://www.cnblogs.com/litianfeng-net/p/13226816.html