Silverlight下的Socket通讯

http://www.cnblogs.com/chengxingliang/archive/2012/05/24/2515100.html

　在Silverlight中进行通讯，只能使用4502-4534之间的端口进行数据传输，另外Silverlight客户端会自动向943端口的服务器端发送一个“<policy-file-request/>”的语句请求，然后服务器端943端口回发以下文件以许可Socket通讯。

<?xml version="1.0" encoding="utf-8" ?>
<access-policy>
  <cross-domain-access>
    <policy>
      <allow-from>
        <domain uri="*"/>
      </allow-from>
      <grant-to>
        <socket-resource port="4502-4534" protocol="tcp"/>
      </grant-to>
    </policy>
  </cross-domain-access>
</access-policy>

　　A.现在我们首先来看服务器端的代码，主要分为策略响应步骤和服务响应步骤。

　　策略步骤一：启动监听943端口是否有需要安全策略文件请求

　　策略步骤二：如果客户端请求是<policy-file-request/>,则将安全策略文件作为bytes发送给客户端

　　服务步骤一：启动服务器端，监听4525端口，是否有Socket对话请求

　　服务步骤二：如果有客户端请求的连接，则发送消息告知客户端

　　代码如下：

    class Program
    {
        static void Main(string[] args)
        {
            //策略步骤一：启动监听943端口是否有需要安全策略文件请求
            Thread access = new Thread(new ThreadStart(accessThread));
            access.Start();

            //服务步骤一：启动服务器端，监听4525端口，是否有Socket对话请求
            Thread server = new Thread(new ThreadStart(ServerThread));
            server.Start();
        }
        //策略请求监听
        static void accessThread()
        {
            //获取943端口监听的Socket服务端
            Socket socket = GetSocketServer(943);
            while (true)
            {
                Socket new_access = socket.Accept();
                string clientPolicyString = "<policy-file-request/>";
                byte[] requestbytes = new byte[clientPolicyString.Length];
                new_access.Receive(requestbytes);
                string requeststring = System.Text.Encoding.UTF8.GetString(requestbytes, 0, requestbytes.Length);

                if (requeststring == clientPolicyString)
                {
                    //策略步骤二：如果客户端请求是<policy-file-request/>,则将安全策略文件作为bytes发送给客户端
                    byte[] accessbytes = GetPolicyToClient();
                    new_access.Send(accessbytes, accessbytes.Length, SocketFlags.None);
                    new_access.Close();
                }
                Thread.Sleep(100);
            }
        }

        static void ServerThread()
        {
            //获取4525端口监听的Socket服务端
            Socket socket = GetSocketServer(4525);
            while (true)
            {
                Socket _socket = socket.Accept();
                //服务步骤二：如果有客户端请求的连接，则发送消息告知客户端
                byte[] b2 = new byte[1024];
                _socket.Receive(b2);
                Console.WriteLine(Encoding.UTF8.GetString(b2).Replace("\0", ""));
                string recString = "我已经收到消息了";
                _socket.Send(Encoding.UTF8.GetBytes(recString));
                _socket.Close();
                Thread.Sleep(100);
            }
        }
        //根据端口建立Socket服务器端
        static Socket GetSocketServer(int serverPort)
        {
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            socket.Bind(new IPEndPoint(IPAddress.Any, serverPort));
            socket.Listen(40);
            return socket;
        }
        //获取安全策略文件的byte[]
        static byte[] GetPolicyToClient()
        {
            string path = Environment.CurrentDirectory.Replace("\\bin\\Debug","");
            FileStream fs = new FileStream(path+ @"\clientaccesspolicy.xml", FileMode.Open);
            int length = (int)fs.Length;
            byte[] bytes = new byte[length];
            fs.Read(bytes, 0, length);
            fs.Close();
            return bytes;
        }

    }

　　B.其次我们来看客户端操作，分为以下几个步骤：

　　客户端步骤一：发起服务器连接请求。

　　客户端步骤二：连接服务器成功，将需要发送的数据放入缓冲区中，然后异步向服务器发送消息请求

　　客户端步骤三：消息发送成功，此时设置一个新的缓冲区实例，并且发起异步接收服务器返回的消息

　　客户端步骤四：获取到服务器返回的消息，关闭Socket　

　　客户端cs代码如下：

    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }
        System.Net.Sockets.Socket socket;

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            byte[] userbytes = Encoding.UTF8.GetBytes(this.tbInput.Text);
            socket = new System.Net.Sockets.Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            SocketAsyncEventArgs socketArgs = new SocketAsyncEventArgs();
            socketArgs.RemoteEndPoint = new DnsEndPoint("127.0.0.1", 4525);
            //将需要发送的内容转为byte[]，保存到UserToken属性中
            socketArgs.UserToken = userbytes;
            socketArgs.Completed += new EventHandler<SocketAsyncEventArgs>(socketArgs_Completed);
            //客户端步骤一：发起服务器连接请求。
            socket.ConnectAsync(socketArgs);
        }
        //每发生一个Socket操作都讲激活此方法，操作包括（Connect/Send/Receive/None）
        void socketArgs_Completed(object sender, SocketAsyncEventArgs e)
        {
            if (e.LastOperation == SocketAsyncOperation.Connect)
            {
                //客户端步骤二：连接服务器成功，将需要发送的数据放入缓冲区中，然后异步向服务器发送消息请求
                byte[] userbytes = (byte[])e.UserToken;
                e.SetBuffer(userbytes, 0, userbytes.Length);
                socket.SendAsync(e);
            }
            else if (e.LastOperation == SocketAsyncOperation.Send)
            {
                //客户端步骤三：消息发送成功，此时设置一个新的缓冲区实例，并且发起异步接收服务器返回的消息
                byte[] userbytes = new byte[1024];
                e.SetBuffer(userbytes, 0, userbytes.Length);
                socket.ReceiveAsync(e);
            }
            else if (e.LastOperation == SocketAsyncOperation.Receive)
            {
                //客户端步骤四：获取到服务器返回的消息，关闭Socket
                string RecevieStr = Encoding.UTF8.GetString(e.Buffer, 0, e.Buffer.Length).Replace("\0", "");
                //因为是异步Socket请求，所以需要使用UI线程更新lbShowMessage的显示效果
                this.lbShowMessage.Dispatcher.BeginInvoke(new DoThingDele(DoThing), RecevieStr);
                socket.Close();
            }
        }
        //更新UI
        public void DoThing(string arg)
        {
            this.lbShowMessage.Content = this.lbShowMessage.Content + "->" + arg;
        }
        //声明的一个DoThing方法委托
        public delegate void DoThingDele(string arg);
    }

　　客户端Xaml前台代码如下：

    <Grid x:Name="LayoutRoot" Background="White" ShowGridLines="True">
        <TextBox Height="23" HorizontalAlignment="Left" Margin="20,20,0,0"
                 Name="tbInput" VerticalAlignment="Top" Width="243" />
        <Button Content="发 送" Height="23" HorizontalAlignment="Left"
                Margin="279,20,0,0" Name="button1" VerticalAlignment="Top"
                Width="75" Click="button1_Click" />
        <sdk:Label Height="28" HorizontalAlignment="Left" Margin="20,57,0,0"
                   Name="lbShowMessage" VerticalAlignment="Top" Width="358" />
    </Grid>

　　最后效果如下，如需源码请点击 SLSocket.zip 下载，本文演示的是最简单通讯效果：