c# - 如何从 WCF 服务返回图像？

Question

我正在尝试从 WCF 服务返回图像。

IService1.cs代码:

[ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
public interface IService1
{
    [OperationContract]
    [WebGet]
    [WebInvoke(BodyStyle = WebMessageBodyStyle.WrappedRequest)]
    Stream GetImage(int width, int height);
}

service1.cs代码:

namespace SecondService
{
    public class Service1 : IService1
    {
        public Stream GetImage(int width, int height)
        {
            // Although this method returns a jpeg, it can be
            // modified to return any data you want within the stream
            Bitmap bitmap = new Bitmap(width, height);
            for (int I = 0; I < bitmap.Width; I++)
            {
                for (int j = 0; j < bitmap.Height; j++)
                {
                    bitmap.SetPixel(I, j, (Math.Abs(I - j) < 2) ? Color.Blue : color.Yellow);
                }
            }

            MemoryStream ms = new MemoryStream();
            bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            ms.Position = 0;

            System.ServiceModel.Channels.TcpTransportBindingElement transport = new  
                System.ServiceModel.Channels.TcpTransportBindingElement();
            transport.TransferMode = TransferMode.Streamed;
            WebOperationContext.Current.OutgoingResponse.ContentType = "image/jpeg";

            return ms;
        }
    }
}

这是我的调用页面的 web.config:

<system.serviceModel>
  <bindings>
    <wsHttpBinding>
      <binding name="WSHttpBinding_IService1"
               closeTimeout="00:01:00"    openTimeout="00:01:00"
               receiveTimeout="00:10:00"  sendTimeout="00:01:00"
               bypassProxyOnLocal="false" transactionFlow="false"
               hostNameComparisonMode="StrongWildcard"
               maxBufferPoolSize="524288" maxReceivedMessageSize="65536" 
               textEncoding="utf-8" useDefaultWebProxy="true"
               allowCookies="false">

        <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384"
                      maxBytesPerRead="4096" maxNameTableCharCount="16384" />
        <reliableSession ordered="true" inactivityTimeout="00:10:00"
                         enabled="false" />
        <security mode="Message">
          <transport clientCredentialType="Windows" proxyCredentialType="None"
                     realm="" />
          <message clientCredentialType="Windows" negotiateServiceCredential="true"
                   algorithmSuite="Default" />
        </security>
      </binding>
    </wsHttpBinding>
  </bindings>

  <client>
    <endpoint address="http://localhost:8732/Design_Time_Addresses/SecondService/Service1/"
              binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IService1"
              contract="ServiceReference1.IService1" name="WSHttpBinding_IService1">

      <identity>
        <dns value="localhost" />
      </identity>
    </endpoint>
  </client>
</system.serviceModel>

当我调用该服务时，出现以下错误:

The content type image/jpeg of the response message does not match the content type of the binding (application/soap+xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly.

我是 WCF 服务的新手，希望能为 WCF 初学者提供有用的链接。

Answer 1

您不能返回一个流，您必须使用如下代码将图像编码为字节数组:

ImageSourceConverter oConverter = new ImageSourceConverter();
BitmapSource oImageSource = (BitmapSource)oConverter.ConvertFromString(sResourceName); // Your resource name

Byte[] oResult; // This is your byte array

using (MemoryStream oStream = new MemoryStream()) 
{
    oEncoder.Frames.Add(BitmapFrame.Create(oImageSource));
    oEncoder.Save(oStream);

    oResult = new byte[oStream.Length];     
    oStream.Position = 0;

    oStream.Read(oResult, 0, (int)oStream.Length);  
    oStream.Close(); 
}