HttpResponseMessage中的InvalidDataContractException

Question

HttpResponseMessage用于Web服务方法，我收到 InvalidDataContractException 。

public HttpResponseMessage GetData()
{

    var fileContent = Encoding.UTF8.GetBytes(
                @"{
                                ""fruit"":""apple"",
                                ""taste"":""yummy""
                                }"
                );
    MemoryStream zipContent = new MemoryStream();
    ZipArchive archive = new ZipArchive(zipContent, ZipArchiveMode.Create);
    Zip_AddEntry("file1.json", fileContent, archive);
    Zip_AddEntry("file2.json", fileContent, archive); //second file (same content)

    zipContent.Position = 0;
    response.Headers.AcceptRanges.Add("bytes");
    response.StatusCode = HttpStatusCode.OK;
    response.Content = new StreamContent(zipContent);
    response.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
    response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
    response.Content.Headers.Add("x-filename", "GenInst_FMS.zip");
    response.Content.Headers.ContentLength = zipContent.Length;

    return response;
}
private static void Zip_AddEntry(string fileName, byte[] fileContent, ZipArchive archive)
{
    var entry = archive.CreateEntry(fileName);
    using (var stream = entry.Open())
        stream.Write(fileContent, 0, fileContent.Length);

}

例外是：

  

System.Runtime.Serialization.InvalidDataContractException，   System.Runtime.Serialization，Version = 4.0.0.0，Culture = neutral，   PublicKeyToken = b77a5c561934e089类型   'System.Net.Http.StreamContent'无法序列化。考虑标记   它与DataContractAttribute属性，并标记其所有   要使用DataMemberAttribute属性序列化的成员。   如果类型是集合，请考虑使用   CollectionDataContractAttribute。请参阅Microsoft .NET Framework   其他支持类型的文档。