【WCF】利用WCF实现上传下载文件服务

定义接口:

 [ServiceContract]
    public interface IFileService
    {

        //上传文件
        [OperationContract]
        bool UpLoadFile(Stream filestream);

        //下载文件
        [OperationContract]
        Stream DownLoadFile(string downfile); 
  
    }

上面方法定义了输入参数和返回参数，但是实际项目中往往是不够的，我们需要增加其他参数，如文件名，文件大小之类。然而WCF中有限定，如下：

• 保留要进行流处理的数据的参数必须是方法中的唯一参数。 例如，如果要对输入消息进行流处理，则该操作必须正好具有一个输入参数。 同样，如果要对输出消息进行流处理，则该操作必须正好具有一个输出参数或一个返回值。

• 参数和返回值的类型中至少有一个必须是 Stream, Message 或 IXmlSerializable。

 [ServiceContract]
    public interface IFileService
    {
        //上传文件
        [OperationContract]
        UpFileResult UpLoadFile(UpFile filestream);

        //下载文件
        [OperationContract]
        DownFileResult DownLoadFile(DownFile downfile);
    }

    [MessageContract]
    public class DownFile
    {
        [MessageHeader]
        public string FileName { get; set; }
    }

    [MessageContract]
    public class UpFileResult
    {
        [MessageHeader]
        public bool IsSuccess { get; set; }
        [MessageHeader]
        public string Message { get; set; }
    }

    [MessageContract]
    public class UpFile
    {
        [MessageHeader]
        public long FileSize { get; set; }
        [MessageHeader]
        public string FileName { get; set; }
        [MessageBodyMember]
        public Stream FileStream { get; set; }
    }

    [MessageContract]
    public class DownFileResult
    {
        [MessageHeader]
        public long   FileSize { get; set; }
        [MessageHeader]
        public bool IsSuccess { get; set; }
        [MessageHeader]
        public string Message { get; set; }
        [MessageBodyMember]
        public Stream FileStream { get; set; }
    }

 public class FileService : IFileService
    {
        public UpFileResult UpLoadFile(UpFile filedata)
        {

            UpFileResult result = new UpFileResult();

            string path = System.AppDomain.CurrentDomain.BaseDirectory +@"\service\";

            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }

            byte[] buffer = new byte[filedata.FileSize];

            FileStream fs = new FileStream(path + filedata.FileName, FileMode.Create, FileAccess.Write);

            int count = 0;
            while ((count = filedata.FileStream.Read(buffer, 0, buffer.Length)) > 0)
            {
                fs.Write(buffer, 0, count);
            }
            //清空缓冲区
            fs.Flush();
            //关闭流
            fs.Close();

            result.IsSuccess = true;

            return result;
          
        }

        //下载文件
        public DownFileResult DownLoadFile(DownFile filedata)
        {

            DownFileResult result = new DownFileResult();

            string path = System.AppDomain.CurrentDomain.BaseDirectory + @"\service\" + filedata.FileName;

            if (!File.Exists(path))
            {
                result.IsSuccess = false;
                result.FileSize = 0;
                result.Message = "服务器不存在此文件";
                result.FileStream = new MemoryStream();
                return result;
            }
            Stream ms = new MemoryStream();   
            FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
            fs.CopyTo(ms);
            ms.Position = 0;  //重要，不为0的话，客户端读取有问题
            result.IsSuccess = true;
            result.FileSize = ms.Length;
            result.FileStream = ms;

            fs.Flush();
            fs.Close();
            return result;
        }
    }

至此，具体实现代码完成，但是我们还需要配置一下App.config，设置地址，契约和绑定。这里绑定采用NetTcpBinding，我们还需要为NetTcpBinding具体配置，如maxReceivedMessageSize（配置最大接收文件大小），transferMode（传输模式，这里是Streamed）等。最终代码如下：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

  <appSettings>
    <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />
  </appSettings>
  <system.web>
    <compilation debug="true" />
  </system.web>
  <!-- 部署服务库项目时，必须将配置文件的内容添加到 
  主机的 app.config 文件中。System.Configuration 不支持库的配置文件。-->
  <system.serviceModel>
    
    <bindings>
       <netTcpBinding>
        <binding name="MyTcpBinding" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" sendTimeout="00:30:00" transferMode="Streamed"   >
          <security mode="None"></security>
        </binding> 
      </netTcpBinding>
    </bindings>
          
    <services>
      <service name="WcfTest.FileService">
        <endpoint address="" binding="netTcpBinding" bindingConfiguration="MyTcpBinding" contract="WcfTest.IFileService">
          <identity>
            <dns value="localhost" />
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
             <add baseAddress="http://localhost:8733/Design_Time_Addresses/WcfTest/Service1/" />
            <add baseAddress="net.tcp://localhost:8734/Design_Time_Addresses/WcfTest/Service1/" />
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- 为避免泄漏元数据信息，
          请在部署前将以下值设置为 false -->
          <serviceMetadata httpGetEnabled="True" httpsGetEnabled="True"/>
          <!-- 要接收故障异常详细信息以进行调试，
          请将以下值设置为 true。在部署前设置为 false 
            以避免泄漏异常信息-->
          <serviceDebug includeExceptionDetailInFaults="False" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>

</configuration>