Silverlight Socket通信学习笔记

      之前因为项目的关系，涉及到与服务器实时通信，比如通过GPRS将GPS的位置信息等信息发送到服务器，然后再转发给Silverlight应用程序，最后在地图上标示出实时的地理位置，查了查相关的资料，网上给出的比较好的方法就是利用Socket与服务器通信。于是这两天看了看Silverlight下的Socket通信，在此将学习的心得和实现过程作一个记录，以供相互学习和交流。

      园子里关于这方面的内容已经有很多大神写过了，这里小小的推荐一下：

      http://www.cnblogs.com/webabcd/archive/2008/12/22/1359551.html

      因此本文的重点知识说一下具体实现的过程，细节和原理性的东西不会太多，因为本人也是新手，所以就不卖弄了。之前说到和地图结合，所以本文的后续工作将会把Silverlight的Socket通信与ArcGIS 的地图结合，来实现一个小小的功能，而本篇则主要关于Socket的实现过程。下面就进入正题吧。

一.Silverlight的Socket通信和控制台、WinForm下的Socket通信有很大的区别。

对于后两者的Socket通信，其过程就是开启端口，绑定端口，监听端口，连接，接收数据，发送数据。

而在Silverlight中则不太一样，在Silverlight中，首先是Silverlight客户端自动向943端口的服务器端发送一个“<policy-file-request/>”的语句请求，然后服务器端向客户端发送策略文件：

clientaccesspolicy.xml，例如：

<?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>

发送之后，才允许和服务器进行Socket通信，之后的过程则都是一样。

二、服务器端

2.1、Silverligh中发送策略文件服务

上面说到，Silverlight中，服务器端会向客户端发送策略文件，然后才能开始Socket通信，下面给出服务器端的发送策略文件服务的代码，该代码是在网上找的，是别人已经写好的一个类，所以在编写Silverlight 的Socket通信程序时，只要添加这个类就好了，代码如下：

using System;
using System.Net.Sockets;
using System.Net;
using System.Threading;
using System.IO;
using System.Windows.Forms;

namespace WindowsServer
{
    class PolicySocketServer
    {
        TcpListener _Listener = null;
        TcpClient _Client = null;
        static ManualResetEvent _TcpClientConnected = new ManualResetEvent(false);
        const string _PolicyRequestString = "<policy-file-request/>";
        int _ReceivedLength = 0;
        byte[] _Policy = null;
        byte[] _ReceiveBuffer = null;

        private void InitializeData()
        {
            string policyFile = Path.Combine(Application.StartupPath, "clientaccesspolicy.xml");
            using (FileStream fs = new FileStream(policyFile, FileMode.Open))
            {
                _Policy = new byte[fs.Length];
                fs.Read(_Policy, 0, _Policy.Length);
            }
            _ReceiveBuffer = new byte[_PolicyRequestString.Length];
        }
        public void StartSocketServer()
        {
            InitializeData();

            try
            {
                _Listener = new TcpListener(IPAddress.Any, 943);
                _Listener.Start();
                while (true)
                {
                    _TcpClientConnected.Reset();
                    _Listener.BeginAcceptTcpClient(new AsyncCallback(OnBeginAccept), null);
                    _TcpClientConnected.WaitOne();
                }
            }
            catch (Exception)
            {
            }
        }

        private void OnBeginAccept(IAsyncResult ar)
        {
            _Client = _Listener.EndAcceptTcpClient(ar);
            _Client.Client.BeginReceive(_ReceiveBuffer, 0, _PolicyRequestString.Length, SocketFlags.None,
                new AsyncCallback(OnReceiveComplete), null);
        }

        private void OnReceiveComplete(IAsyncResult ar)
        {
            try
            {
                _ReceivedLength += _Client.Client.EndReceive(ar);
                if (_ReceivedLength < _PolicyRequestString.Length)
                {
                    _Client.Client.BeginReceive(_ReceiveBuffer, _ReceivedLength,
                        _PolicyRequestString.Length - _ReceivedLength,
                        SocketFlags.None, new AsyncCallback(OnReceiveComplete), null);
                    return;
                }
                string request = System.Text.Encoding.UTF8.GetString(_ReceiveBuffer, 0, _ReceivedLength);
                if (StringComparer.InvariantCultureIgnoreCase.Compare(request, _PolicyRequestString) != 0)
                {
                    _Client.Client.Close();
                    return;
                }
                _Client.Client.BeginSend(_Policy, 0, _Policy.Length, SocketFlags.None,
                    new AsyncCallback(OnSendComplete), null);
            }
            catch (Exception)
            {
                _Client.Client.Close();
            }
            _ReceivedLength = 0;
            _TcpClientConnected.Set(); //Allow waiting thread to proceed 
        }

        private void OnSendComplete(IAsyncResult ar)
        {
            try
            {
                _Client.Client.EndSendFile(ar);
            }
            catch (Exception)
            {
            }
            finally
            {
                _Client.Client.Close();
            }
        } 
    }
}

2.2、启动策略文件服务，声明Socket，监听端口，接收数据，发送数据。

启动策略文件服务

#region Start The Policy Server 验证策略文件
            PolicySocketServer StartPolicyServer = new PolicySocketServer();
            Thread th = new Thread(new ThreadStart(StartPolicyServer.StartSocketServer));
            th.IsBackground = true;
            th.Start();
            #endregion 

声明Socket，绑定端口，开始监听

 private void StartButton_Click(object sender, EventArgs e)
        {//创建Socket
            listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            //获取主机信息
            IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());

            //把IP和端口转换化为IPEndPoint实例,端口号取4530
            //Win7 中开启了IPV6的地址，因此0,1对应的是IPV6的地址，2，3对应IPV4地址，3对应本机的IP地址
            //XP中没有开启IPV6
            HostIPTextBox.Text = ipHostInfo.AddressList[3].ToString();

            if (!string.IsNullOrEmpty(PortTextBox.Text))
            {
                //获取端口号
                int port = Convert.ToInt32(PortTextBox.Text.Trim());
                //获得本机的IP地址
                localEP = new IPEndPoint(ipHostInfo.AddressList[3], port);
            }
            else
            {
               //默认4530端口
                ipAddress = IPAddress.Parse("127.0.0.1");
                localEP = new IPEndPoint(ipHostInfo.AddressList[3], 4530);
            }

            try
            {
                //绑定指定的终结点
                listener.Bind(localEP);
                //开始监听
                listener.Listen(10);
                //一直循环接收客户端的消息，开启监听端口线程
                ThreadStart threadwatchStart = new ThreadStart(WatchConnecting);
                threadWatch = new Thread(threadwatchStart);
                threadWatch.IsBackground = true;
                threadWatch.Start();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Data.ToString());
            }
        }

连接端口，接收数据

   private void WatchConnecting()
        {
            ChangeStatue("等待Silverlight客户端连接.....");
            while (true)  //持续不断监听客户端发来的请求  
            {
                listener.BeginAccept(AcceptCallBack, listener);
                _flipFlop.WaitOne();
            }
        }

 private  void AcceptCallBack(IAsyncResult asyresult)
        {
            Socket listener = (Socket)asyresult.AsyncState;
            Socket socket = listener.EndAccept(asyresult);
            ChangeStatue("连接到Silverlight客户端....");
            _flipFlop.Set();
            var state = new StateObject();
            state.Socket = socket;
            socket.BeginReceive(state.Buffer, 0, StateObject.BufferSize, 0, ReciverCallBack, state);
        }

  private void ReciverCallBack(IAsyncResult asyResult)
        {
            StateObject state = (StateObject)asyResult.AsyncState;
            Socket socket = state.Socket;
            int read = socket.EndReceive(asyResult);
            if (read > 0)
            {
                string chunk = Encoding.UTF8.GetString(state.Buffer, 0, read);
                state.StringBuilder.Append(chunk);
                if (state.StringBuilder.Length > 0)
                {
                    string result = state.StringBuilder.ToString();
                    ChangeStatue("成功接收到消息："+result);
                    ChangeReciveText(result);
                    Send(socket, SendTextBox.Text);
                    AddListItems("接收消息："+result+"\n");
                    AddListItems("发送消息：" + SendTextBox.Text + "\n");
                }
            }
        }

发送数据

 private void Send(Socket handler, String data)
        {
            byte[] byteData = Encoding.UTF8.GetBytes(data);
            handler.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallBack), handler);
        }

        private void SendCallBack(IAsyncResult asyResult)
        {
            try
            {
                Socket handler = (Socket)asyResult.AsyncState;
                int byteSent = handler.EndSend(asyResult);
                if (byteSent > 0)
                {
                    ChangeStatue("发送数据成功！");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Data.ToString());
            }
        }

StateObject类：

 public class StateObject
    {
        public Socket Socket;
        public StringBuilder StringBuilder = new StringBuilder();
        public const int BufferSize = 1024;
        public byte[] Buffer = new byte[BufferSize];
        public int TotalSize;
    }

客户端：

 和服务器端类似，客户端的操作包括：声明Socket，指定服务器地址和端口，连接到指定的服务器端口，发送数据，接收数据。

下面是具体的实现代码：

声明Socket

private Socket socket;

指定服务器地址和端口，开始连接

  private void SendButton_Click(object sender, RoutedEventArgs e)
        {
            if(string.IsNullOrEmpty(IPTextBox.Text)||string.IsNullOrEmpty(PortTextBox.Text))
            {
                MessageBox.Show ("请输入主机IP地址和端口号！");
                return;
            }
            //ip地址
            string host=IPTextBox.Text.Trim();
            //端口号
            int port=Convert.ToInt32(PortTextBox.Text.Trim());
            //建立终结点对象
            DnsEndPoint hostEntry=new DnsEndPoint(host,port);
            //创建一个Socket对象
            socket=new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            //创建Socket异步事件参数
            SocketAsyncEventArgs socketEventArg=new SocketAsyncEventArgs ();
            //将消息转化为发送的byte[]格式
            byte[]buffer=Encoding.UTF8.GetBytes(MessageTextBox.Text);
            //注册Socket完成事件
            socketEventArg.Completed+=new EventHandler<SocketAsyncEventArgs>(socketEventArg_Completed);
            //设置Socket异步事件远程终结点
            socketEventArg.RemoteEndPoint=hostEntry;
            //将定义好的Socket对象赋值给Socket异步事件参数的运行实例属性
            socketEventArg.UserToken = buffer;
            try
            {
                socket.ConnectAsync(socketEventArg);
            }
            catch(SocketException ex)
            {
                throw new SocketException((int)ex.ErrorCode);
            }
        }

向服务器发送数据，并接受服务器回复的消息。

 private void socketEventArg_Completed(object sender, SocketAsyncEventArgs e)
        {
           //检查是否发送出错
            if (e.SocketError != SocketError.Success)
            {
                if (e.SocketError == SocketError.ConnectionAborted)
                {
                    Dispatcher.BeginInvoke(() => MessageBox.Show("连接超时....请重试！"));
                }
                else if (e.SocketError == SocketError.ConnectionRefused)
                {
                    Dispatcher.BeginInvoke(() => MessageBox.Show("无法连接到服务器端："+e.SocketError));
                }else
                {
                    Dispatcher.BeginInvoke(() => MessageBox.Show("出错了！"+e.SocketError));
                }
                return;
            }
           //如果连接上，则发送数据
            if (e.LastOperation == SocketAsyncOperation.Connect)
            {
                    byte[] userbytes = (byte[])e.UserToken;
                    e.SetBuffer(userbytes, 0, userbytes.Length);
                    socket.SendAsync(e);
                    
            }//如果已发送数据，则开始接收服务器回复的消息
            else if (e.LastOperation == SocketAsyncOperation.Send)
            {
                Dispatcher.BeginInvoke(() =>
                {
                    listBox1.Items.Add("客户端在" + DateTime.Now.ToShortTimeString() + "，发送消息：" + MessageTextBox.Text);
                });
                byte[] userbytes = new byte[1024];
                e.SetBuffer(userbytes, 0, userbytes.Length);
                socket.ReceiveAsync(e);
            }//接收服务器数据
            else if (e.LastOperation == SocketAsyncOperation.Receive)
            {
                string RecevieStr = Encoding.UTF8.GetString(e.Buffer, 0, e.Buffer.Length).Replace("\0", "");
                Dispatcher.BeginInvoke(() =>
                {
                    listBox1.Items.Add("服务器在" + DateTime.Now.ToShortTimeString() + "，回复消息：" + RecevieStr);
                });
                socket.Close();
            }
        }
   

xaml代码：

<UserControl
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:esri="http://schemas.esri.com/arcgis/client/2009" x:Class="SilverlightSocket.MainPage"
    mc:Ignorable="d"
    d:DesignHeight="417" d:DesignWidth="530">

    <Grid x:Name="LayoutRoot" Background="White">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="0.868*"/>
            <ColumnDefinition Width="0.135*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <esri:Map Background="White" WrapAround="True" Grid.ColumnSpan="2">
            <esri:ArcGISTiledMapServiceLayer Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"/>
        </esri:Map>
        <StackPanel Grid.Column="1" Background="#7F094870">
            <StackPanel.Effect>
                <DropShadowEffect/>
            </StackPanel.Effect>
            <TextBlock x:Name="textBlock1" Text="主机IP" Grid.Column="1" Margin="5,5,0,0" Foreground="#FFE7D4E3" FontWeight="Bold" />
            <TextBox x:Name="IPTextBox" Text="169.254.57.67" Grid.Column="1" d:LayoutOverrides="Width" Margin="5,5,0,0" HorizontalAlignment="Left"/>
            <TextBlock x:Name="textBlock2" Text="端口号" Grid.Column="1" Margin="5,5,0,0" Foreground="#FFE7D4E3" FontWeight="Bold" />
            <TextBox x:Name="PortTextBox" Width="51" Text="4530" Grid.Column="1" Margin="5,5,0,0" HorizontalAlignment="Left"/>
            <TextBlock  x:Name="textBlock4" Text="消息记录：" Height="23" Grid.Column="1" Margin="5,5,0,0" Foreground="#FFE7D4E3" FontWeight="Bold" />
            <ListBox  x:Name="listBox1" Grid.Column="1" Margin="5,5,0,0" Height="150" />
            <TextBlock x:Name="textBlock3" Text="发送信息内容" Height="16" Grid.Column="1" d:LayoutOverrides="Width" Margin="5,5,0,0" Foreground="#FFE7D4E3" FontWeight="Bold" />
            <TextBox x:Name="MessageTextBox" Grid.Column="1" Height="50" Margin="5,5,0,0" />
            <Button Content="发送" Height="23" x:Name="SendButton" Grid.Column="1" Margin="5,5,0,0" />
            <Button Content="清空" Height="23" x:Name="ClearButton" Grid.Column="1" Margin="5,5,0,0" />
        </StackPanel>
    </Grid>
</UserControl>

最后效果示意图：

服务器端：

Silverlight客户端：

后续工作中将结合地图来实现模拟实时位置的显示功能。。。。

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