转：WCF传送二进制流数据基本实现步骤详解

我们知道，在实现WCF传送二进制流数据这一操作过程中，会有一些限制因素。我们在实际应用中要特别注意这一点。今天我们就会针对这方面的问题做一个详细的介绍，希望对大家有所帮助。

只有 BasicHttpBinding、WebHttpBinding、NetTcpBinding 和 NetNamedPipeBinding 支持传送流数据。
流数据类型必须是可序列化的 Stream 或 MemoryStream。
传递时消息体(Message Body)中不能包含其他数据。

我们先看看下面的WCF传送二进制流数据例子。

注意将 Binding.TransferMode 设置为 TransferMode.Streamed，我们还可以修改 Binding.MaxReceivedMessageSize 来调整消息大小(默认是64KB)。

    [ServiceContract]
    public interface IFileService
    {
        [OperationContract]
        void Upload(Stream stream);
    }
    public class FileService : IFileService, IDisposable
    {
        public void Upload(Stream stream)
        {
            FileStream file = new FileStream("test.dll", FileMode.Create);
            try
            {
                BinaryWriter writer = new BinaryWriter(file);
                BinaryReader reader = new BinaryReader(stream);
                byte[] buffer; do { buffer = reader.ReadBytes(1024); writer.Write(buffer); } while (buffer.Length > 0);
            }
            finally 
            { 
                file.Close(); 
                stream.Close(); 
            }
        } 
        public void Dispose() 
        { 
            Console.WriteLine("Dispose...");
        }
    }
    public class WcfTest
    {
        public static void Test()
        {
            AppDomain.CreateDomain("Server").DoCallBack(delegate
            {
                ServiceHost host = new ServiceHost(typeof(FileService), new Uri("http://localhost:8080/FileService"));
                BasicHttpBinding binding = new BasicHttpBinding();
                binding.TransferMode = TransferMode.Streamed;
                host.AddServiceEndpoint(typeof(IFileService), binding, "");
                host.Open();
            });
            BasicHttpBinding binding2 = new BasicHttpBinding();
            binding2.TransferMode = TransferMode.Streamed;
            IFileService channel = ChannelFactory<IFileService>.CreateChannel(binding2, new EndpointAddress("http://localhost:8080/FileService"));
            using (channel as IDisposable)
            {
                FileStream stream = new FileStream("MyLibrary2.dll", FileMode.Open);
                channel.Test(stream);
                stream.Close();
            }
        }
    }

一切正常。那么 "传递时消息体(Memory Body)中不能包含其他数据" 是什么意思？我们修改一下上面的契约，除了传递文件流外，我们还希望传递文件名。

    [ServiceContract]
    public interface IFileService
    {
        [OperationContract]
        void Upload(string filename, Stream stream);
    }  
    // ... 其他代码暂略 ...

当你修改完WCF传送二进制流数据的代码后，运行时你发现触发了一个 InvalidOperationException 异常。

未处理 System.InvalidOperationException
Message="For request in operation Upload to be a stream the operation must have a single parameter whose type is Stream."
Source="System.ServiceModel"

那么该怎么办呢？DataContract 肯定不行。没错！你应该记得 MessageContract，将 filename 放到 MessageHeader 里面就行了。

    [MessageContract]
    public class FileData
    {
        [MessageHeader]
        public string filename;
        [MessageBodyMember]
        public Stream data;
    }
    [ServiceContract]
    public interface IFileService
    {
        [OperationContract]
        void Upload(FileData file);
    }
    public class FileService : IFileService, IDisposable
    {
        public void Upload(FileData file)
        {
            FileStream f = new FileStream(file.filename, FileMode.Create);
            try
            {
                BinaryWriter writer = new BinaryWriter(f);
                BinaryReader reader = new BinaryReader(file.data);
                byte[] buffer;
                do
                {
                    buffer = reader.ReadBytes(1024); writer.Write(buffer);
                } while (buffer.Length > 0);
            }
            finally
            {
                f.Close(); file.data.Close();
            }
        }
        public void Dispose()
        {
            Console.WriteLine("Dispose...");
        }
    }
    public class WcfTest
    {
        public static void Test()
        {
            AppDomain.CreateDomain("Server").DoCallBack(delegate 
            { 
                ServiceHost host = new ServiceHost(typeof(FileService), new Uri("http://localhost:8080/FileService")); 
                BasicHttpBinding binding = new BasicHttpBinding(); 
                binding.TransferMode = TransferMode.Streamed; 
                host.AddServiceEndpoint(typeof(IFileService), binding, ""); 
                host.Open(); 
            }); 
            BasicHttpBinding binding2 = new BasicHttpBinding(); 
            binding2.TransferMode = TransferMode.Streamed; 
            IFileService channel = ChannelFactory<IFileService>.CreateChannel(binding2, new EndpointAddress("http://localhost:8080/FileService")); 
            using (channel as IDisposable)
            {
                FileData file = new FileData(); 
                file.filename = "test2.dll"; 
                file.data = new FileStream("MyLibrary2.dll", FileMode.Open); 
                channel.Upload(file); file.data.Close();
            }
        }
    }

问题解决了。上面的例子使用 BaseHttpBinding，如果使用 NetTcpBinding，相信速度要快很多。除了向服务器传送流外，也可反向返回流数据。

    [ServiceContract]
    public interface IFileService
    {
        [OperationContract]
        void Upload(Stream stream);
        [OperationContract]
        Stream Download(string filename);
    }

虽然服务器在操作结束时会自动关闭客户端 Request Stream，但个人建议还是使用 try...finnaly... 自主关闭要好一些，因为意外总是会发生的。

WCF传送二进制流数据的全部操作方法就为大家介绍到这里。