Windows Mobile上的GPRS连接(基于TcpClient)

 

在有线的连接和WIFI都不可用的时候, .NET CF的HttpWebRequest会由于web requests/web services 而自动设置GPRS连接。所以实际上当你发起一个Web请求或者连接Webservice的时候，并不需要开发者编码处理GPRS的连接问题。不过对于更低层的通信，如使用TcpClient 和 UdpClient的时候，则需要使用 Connection Manager API来建立和释放连接。

 

(本文英文原文见：)

 

以下托管类是对Connection Manager API的封装

    

public

 

class

 GPRSConnection

    

{

        const int S_OK = 0;

        const uint CONNMGR_PARAM_GUIDDESTNET = 0x1;

        const uint CONNMGR_FLAG_PROXY_HTTP = 0x1;

        const uint CONNMGR_PRIORITY_USERINTERACTIVE = 0x08000;

        const uint INFINITE = 0xffffffff;

        const uint CONNMGR_STATUS_CONNECTED = 0x10;

        static Hashtable ht = new Hashtable();

        static GPRSConnection()

        {

            ManualResetEvent mre = new ManualResetEvent(false);

            mre.Handle = ConnMgrApiReadyEvent();

            mre.WaitOne();

            CloseHandle(mre.Handle);

        }

        ~GPRSConnection()

        {

            ReleaseAll();

        }

        public static bool Setup(Uri url)

        {

            return Setup(url.ToString());

        }

        public static bool Setup(string urlStr)

        {

            ConnectionInfo ci = new ConnectionInfo();

            IntPtr phConnection = IntPtr.Zero;

            uint status = 0;

            if (ht[urlStr] != null)

                return true;

            if (ConnMgrMapURL(urlStr, ref ci.guidDestNet, IntPtr.Zero) != S_OK)

                return false;

            

            ci.cbSize = (uint) Marshal.SizeOf(ci);

            ci.dwParams = CONNMGR_PARAM_GUIDDESTNET;

            ci.dwFlags = CONNMGR_FLAG_PROXY_HTTP;

            ci.dwPriority = CONNMGR_PRIORITY_USERINTERACTIVE;

            ci.bExclusive = 0;

            ci.bDisabled = 0;

            ci.hWnd = IntPtr.Zero;

            ci.uMsg = 0;

            ci.lParam = 0;

            if (ConnMgrEstablishConnectionSync(ref ci, ref phConnection, INFINITE, ref status) != S_OK &&

                status != CONNMGR_STATUS_CONNECTED)

                return false;

            ht[urlStr] = phConnection;

            return true;

        }

        public static bool Release(Uri url)

        {

            return Release(url.ToString());

        }

        public static bool Release(string urlStr)

        {

            return Release(urlStr, true);

        }

        private static bool Release(string urlStr, bool removeNode)

        {

            bool res = true;

            IntPtr ph = IntPtr.Zero;

            if (ht[urlStr] == null)

                return true;

            ph = (IntPtr)ht[urlStr];

            if (ConnMgrReleaseConnection(ph, 1) != S_OK)

                res = false;

            CloseHandle(ph);

            if (removeNode)

                ht.Remove(urlStr);

            return res;

        }

        public static void ReleaseAll()

        {

           foreach(DictionaryEntry de in ht)

           {

               Release((string)de.Key, false);

           }

           ht.Clear();

        }

        [StructLayout(LayoutKind.Sequential)]

        public struct ConnectionInfo

        {

            public uint cbSize;

            public uint dwParams;

            public uint dwFlags;

            public uint dwPriority;

            public int bExclusive;

            public int bDisabled;

            public Guid guidDestNet;

            public IntPtr hWnd;

            public uint uMsg;

            public uint lParam;

            public uint ulMaxCost;

            public uint ulMinRcvBw;

            public uint ulMaxConnLatency;

        }

        [DllImport("cellcore.dll")]

        private static extern int ConnMgrMapURL(string pwszURL, ref Guid pguid, IntPtr pdwIndex);

        [DllImport("cellcore.dll")]

        private static extern int ConnMgrEstablishConnectionSync(ref ConnectionInfo ci, ref IntPtr phConnection, uint dwTimeout, ref uint pdwStatus);

        [DllImport("cellcore.dll")]

        private static extern IntPtr ConnMgrApiReadyEvent();

        [DllImport("cellcore.dll")]

        private static extern int ConnMgrReleaseConnection(IntPtr hConnection, int bCache);

        [DllImport("coredll.dll")]

        private static extern int CloseHandle(IntPtr hObject);

    }

使用GPRSConnection class的时候, 先调用Setup方法创建连接，见以下代码：

 

 

        

public

 

void

 DoTcpConnection()

        

{

            string url = "www.msn.com";

            bool res = GPRSConnection.Setup("http://" + url + "/");

            if (res)

            {

                TcpClient tc = new TcpClient(url, 80);

                NetworkStream ns = tc.GetStream();

                byte[] buf = new byte[100];

                ns.Write(buf, 0, 100);

                tc.Client.Shutdown(SocketShutdown.Both);

                ns.Close();

                tc.Close();

                MessageBox.Show("Wrote 100 bytes");

            }

            else

            {

                MessageBox.Show("Connection establishment failed");

            }

        }

Enjoy,

 

黄季冬