使用C＃通过HTTP POST发送文件

使用.NET 4.5（或通过从NuGet
添加Microsoft.Net.Http包的.NET 4.0 ），可以模拟表单请求。这是一个例子：

private async Task<System.IO.Stream> Upload(string actionUrl, string paramString, Stream paramFileStream, byte [] paramFileBytes){    HttpContent stringContent = new StringContent(paramString);    HttpContent fileStreamContent = new StreamContent(paramFileStream);    HttpContent bytesContent = new ByteArrayContent(paramFileBytes);    using (var client = new HttpClient())    using (var formData = new MultipartFormDataContent())    {        formData.Add(stringContent, "param1", "param1");        formData.Add(fileStreamContent, "file1", "file1");        formData.Add(bytesContent, "file2", "file2");        var response = await client.PostAsync(actionUrl, formData);        if (!response.IsSuccessStatusCode)        { return null;        }        return await response.Content.ReadAsStreamAsync();    }}