轉：WCF傳送二進制流數據基本實現步驟詳解

咱們知道，在實現WCF傳送二進制流數據這一操做過程當中，會有一些限制因素。咱們在實際應用中要特別注意這一點。今天咱們就會針對這方面的問題作一個詳細的介紹，但願對你們有所幫助。spa

只有 BasicHttpBinding、WebHttpBinding、NetTcpBinding 和 NetNamedPipeBinding 支持傳送流數據。
流數據類型必須是可序列化的 Stream 或 MemoryStream。
傳遞時消息體(Message Body)中不能包含其餘數據。code

咱們先看看下面的WCF傳送二進制流數據例子。htm

注意將 Binding.TransferMode 設置爲 TransferMode.Streamed，咱們還能夠修改 Binding.MaxReceivedMessageSize 來調整消息大小(默認是64KB)。對象

    [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。那麼 "傳遞時消息體(Memory Body)中不能包含其餘數據" 是什麼意思？咱們修改一下上面的契約，除了傳遞文件流外，咱們還但願傳遞文件名。blog

    [ServiceContract]
    public interface IFileService
    {
        [OperationContract]
        void Upload(string filename, Stream stream);
    }  
    // ... 其餘代碼暫略 ...

當你修改完WCF傳送二進制流數據的代碼後，運行時你發現觸發了一個 InvalidOperationException 異常。事務

未處理 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"ip

那麼該怎麼辦呢？DataContract 確定不行。沒錯！你應該記得 MessageContract，將 filename 放到 MessageHeader 裏面就好了。get

    [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();
            }
        }
    }

問題解決了。上面的例子使用 BaseHttpBinding，若是使用 NetTcpBinding，相信速度要快不少。除了向服務器傳送流外，也可反向返回流數據。

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

雖然服務器在操做結束時會自動關閉客戶端 Request Stream，但我的建議仍是使用 try...finnaly... 自主關閉要好一些，由於意外老是會發生的。

WCF傳送二進制流數據的所有操做方法就爲你們介紹到這裏。