Question

我试图从WCF服务获取图像
我有一个OperationContract函数，它将Image返回给客户端，但是当我从客户端调用它时我得到了这个例外：The socket connection was aborted. This could be caused by an error processing your message or a receive timeout being exceeded by the remote host, or an underlying network resource issue. Local socket timeout was '00:00:59.9619978'.

客户：

private void btnNew_Click(object sender, EventArgs e)
    {
        picBox.Picture = client.GetScreenShot();
    }

Service.cs：

public Image GetScreenShot()
    {
        Rectangle bounds = Screen.GetBounds(Point.Empty);
        using (Bitmap bmp = new Bitmap(bounds.Width,bounds.Height))
        {
            using (Graphics g = Graphics.FromImage(bmp))
            {
                g.CopyFromScreen(Point.Empty, Point.Empty, bounds.Size);
            }
            using (MemoryStream ms = new MemoryStream())
            {
                bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                return Image.FromStream(ms);
            }
        }
    }

IScreenShot界面：

    [ServiceContract]
public interface IScreenShot
{
    [OperationContract]
    System.Drawing.Image GetScreenShot();
}

那为什么会发生这种情况，我该如何解决？

Answer 1

我已经明白了。

首先使用TransferMode.Streamed //或StreamedResponse取决于您的需要。
返回流，不要忘记设置Stream.Postion = 0，所以开始从开头读取流。

在服务中：

    public Stream GetStream()
    {
        Rectangle bounds = Screen.GetBounds(Point.Empty);
        using (Bitmap bmp = new Bitmap(bounds.Width, bounds.Height))
        {
            using (Graphics g = Graphics.FromImage(bmp))
            {
                g.CopyFromScreen(Point.Empty, Point.Empty, bounds.Size);
            }
            MemoryStream ms = new MemoryStream();
            bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            ms.Position = 0;  //This's a very important
            return ms;
        }
    }

界面：

[ServiceContract]
public interface IScreenShot
{
    [OperationContract]
    Stream GetStream();
}

在客户端：

public partial class ScreenImage : Form
{
    ScreenShotClient client;
    public ScreenImage(string baseAddress)
    {
        InitializeComponent();
        NetTcpBinding binding = new NetTcpBinding(SecurityMode.None);
        binding.TransferMode = TransferMode.StreamedResponse;
        binding.MaxReceivedMessageSize = 1024 * 1024 * 2;
        client = new ScreenShotClient(binding, new EndpointAddress(baseAddress));
    }

    private void btnNew_Click(object sender, EventArgs e)
    {
        picBox.Image = Image.FromStream(client.GetStream());
    }
}

Answer 2

您可以使用Stream返回大数据/图像。

Sample Example(returning Image as Stream) from MSDN

Answer 3

您需要定义可序列化的内容。 System.Drawing.Image是，但默认情况下不在WCF的cotnext中（使用DataContractSerializer）。这可能包括将原始字节作为数组返回，或将序列化返回到字符串（base64，JSON）或实现可序列化的DataContract并且可以随身携带数据。

正如其他人所说，WCF支持流媒体，但这不是问题的症结所在。根据您可能希望执行此操作的数据大小，这样做会减少问题，因为您将流式传输字节（从明显的顶级视图）。

您还可以take a look at this answer帮助您获取实际的异常详细信息，例如完整的堆栈跟踪，而不仅仅是故障信息。

从OperationContract方法返回图像（WCF服务）

3 个答案: