.NET使用HttpClient以multipart/form-data形式post上传文件及其相关参数

<div class="cover-hd">
<a href="javascript:;" class="a-uploadCustom">
<input type="file" id="Logoimg" onchange="OnchangeImage(this)" /></a>
</div>

<script type="text/javascript">
    //后端图片上传
    function OnchangeImage(obj) {
        var formData = new FormData();
        var files = $(obj).prop('files'); //获取到文件列表
        console.log(files[0]);
        formData.append("imgType", 1);
        formData.append("appId","你需要传递的参数");
        formData.append("random", "你需要传递的参数");
        formData.append("file", files[0]);//图片文件流
        formData.append("sign", "你需要传递的参数");
        console.log(formData);
        jQuery.support.cors = true;
        $.ajax({
            async: true,
            contentType: false, //头部请求内容格式
            dataType: 'json',
            type: 'post',
            data:formData,
            // 告诉jQuery不要去处理发送的数据
            processData: false,
            url: "@Url.Action("ImageUpload", "MtVirtualStore")",//后端接收图片接口
            success: function(data) {
                //后端Httpclient请求成功后返回过来的结果
                console.log(data);
            }
        });
    }
</script>

//接收前端图片文件信息
[HttpPost]
public JsonResult ImageUpload(FormContext context)
{
HttpPostedFileBase fileData = Request.Files[0];
string appId=Request["appId"];
string random=Request["random"];
string sign=Request["sign"];
string imgType=Request["imgType"];
if (fileData != null)
{
try{
string fileName = Path.GetFileName(fileData.FileName);//原始文件名称
byte[] byteFileData = ReadFileBytes(fileData);//文件流转为字节流
var resultContext =HttpClientPostUpload(byteFileData,appId,random,sign,imgType, fileName);
return Json(new { code = 1, list = resultContext,msg="上传成功~"});
}
catch (Exception ex)
{
return Json(new { code = 0, msg = ex.Message });
}
}
else
{
return Json(new { code = 0, msg = "图片上传失败，请稍后再试~" });
}
}
//文件流转化为字节
/// <summary>
/// 文件流类型转化字节类型
/// </summary>
/// <param name="fileData">文件流数据</param>
/// <returns></returns>
private byte[] ReadFileBytes(HttpPostedFileBase fileData)
{
byte[] data;
using (Stream inputStream = fileData.InputStream)
{
MemoryStream memoryStream = inputStream as MemoryStream;
if (memoryStream == null)
{
memoryStream = new MemoryStream();
inputStream.CopyTo(memoryStream);
}
data = memoryStream.ToArray();
}
return data;
}

/// <summary>
/// 向目标地址提交图片文件参数数据
/// </summary>
/// <param name="bmpBytes">图片字节流</param>
/// <param name="appId">appid</param>
/// <param name="random">随机数</param> 
/// <param name="sign">签名</param>
/// <param name="imgType">上传图片类型</param>     
/// <param name="fileName">图片名称</param>
/// <returns></returns>
public string HttpClientPostUpload(byte [] bmpBytes, string appId, string random,string sign,string imgType,string fileName)
{
using (var client = new HttpClient())
{
List<ByteArrayContent> list = new List<ByteArrayContent>();
var dataContent = new ByteArrayContent(Encoding.UTF8.GetBytes(appId));
dataContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")//内容处置标头
{
Name = "appId"
};
list.Add(dataContent);
var dataContent2 = new ByteArrayContent(Encoding.UTF8.GetBytes(imgType));
dataContent2.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
{
Name = "imgType"
};
list.Add(dataContent2);
var dataContent3 = new ByteArrayContent(Encoding.UTF8.GetBytes(random));
dataContent3.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
{
Name = "random"
};
list.Add(dataContent3);
var dataContent4 = new ByteArrayContent(Encoding.UTF8.GetBytes(sign));
dataContent4.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
{
Name = "sign"
};
list.Add(dataContent4);var fileContent = new ByteArrayContent(bmpBytes);//填充图片字节
fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
{
Name="file",
FileName=fileName
};
list.Add(fileContent);
using (var content =new MultipartFormDataContent())
{
Action<List<ByteArrayContent>> act = (dataContents) =>
{//声明一个委托，该委托的作用就是将ByteArrayContent集合加入到MultipartFormDataContent中
foreach (var byteArrayContent in dataContents)
{
content.Add(byteArrayContent);
}
};
act(list);//执行act
try
{
var result = client.PostAsync("https://xxxxxx.com/imageUpload/", content).Result;//post请求
return result.Content.ReadAsStringAsync().Result;
}
catch (Exception ex)
{
return ex.Message;
}
}
}
}