在網絡編程中,有時候會需要重新撥號建立網絡連接(如Ad點擊軟件通過重新撥號形成有效點擊) ,下面介紹兩種程序中撥號的方法.

1、最簡單的方法：使用RasDialming令

RasDial是Windows自帶的ming令，使用非常簡單。實際使用是可將下面代碼保存為一個批處理文件，然后直接運行或在程序里進行調用。

rasdial.exe /disconnect '斷開連接

del "C:/Documents and Settings/hyuqin/Cookies/*.*" /Q '清除Cookie

rasdial.exe 連接名 連接賬戶 連接密碼 '重新撥號

2、封裝為類，靈活調用

上面提到的方法雖然很簡單，但并非標準的實現方法，使用時會受到一些限制，此時最好的辦法就是將實現代碼封裝為類庫。下面這個類庫是網上一位朋友提供的,直接調用就行.

using System;
        using System.Runtime.InteropServices;

        public struct RASCONN
        {
                public int dwSize;
                public IntPtr hrasconn;
                [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 257)]
                public string szEntryName;
                [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 17)]
                public string szDeviceType;
                [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 129)]
                public string szDeviceName;
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
        public struct RasStats
        {
                public int dwSize;
                public int dwBytesXmited;
                public int dwBytesRcved;
                public int dwFramesXmited;
                public int dwFramesRcved;
                public int dwCrcErr;
                public int dwTimeoutErr;
                public int dwAlignmentErr;
                public int dwHardwareOverrunErr;
                public int dwFramingErr;
                public int dwBufferOverrunErr;
                public int dwCompressionRatioIn;
                public int dwCompressionRatioOut;
                public int dwBps;
                public int dwConnectionDuration;
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
        public struct RasEntryName
        {
                public int dwSize;
                //[MarshalAs(UnmanagedType.ByValTStr,SizeConst=(int)RasFieldSizeConstants.RAS_MaxEntryName + 1)] 
                public string szEntryName;
                //#if WINVER5
                // public int dwFlags;
                // [MarshalAs(UnmanagedType.ByValTStr,SizeConst=260+1)]
                // public string szPhonebookPath;
                //#endif
        }
        public class RAS
        {
                [DllImport("Rasapi32.dll", EntryPoint = "RasEnumConnectionsA",SetLastError = true)]

                internal static extern int RasEnumConnections
                (
                ref RASCONN lprasconn, // buffer to receive connections data 
                ref int lpcb, // size in bytes of buffer 
                ref int lpcConnections // number of connections written to buffer );

                [DllImport("rasapi32.dll" , CharSet = CharSet.Auto)]
                internal static extern uint RasGetConnectionStatistics(
                IntPtr hRasConn, // handle to the connection
                [In, Out]RasStats lpStatistics // buffer to receive statistics
                );
                [DllImport("rasapi32.dll", CharSet = CharSet.Auto)]
                public extern static uint RasHangUp(
                        IntPtr hrasconn // handle to the RAS connection to hang up );

                [DllImport("rasapi32.dll", CharSet = CharSet.Auto)]
                public extern static uint RasEnumEntries(
                string reserved, // reserved, must be NULL
                string lpszPhonebook, // pointer to full path and
                // file name of phone-book file [In, Out]RasEntryName[] lprasentryname, // buffer to receive
                // phone-book entries
                ref int lpcb, // size in bytes of buffer 
                out int lpcEntries // number of entries written
                // to buffer 
                );

                [DllImport("wininet.dll", CharSet = CharSet.Auto)]
                public extern static int InternetDial(
                IntPtr hwnd,
                [In]string lpszConnectoid,
                uint dwFlags,
                ref int lpdwConnection,
                uint dwReserved
                );

                public RAS()
                {
                }
        }
        public enum DEL_CACHE_TYPE //要刪除的類型。
        {
                File,//表示internet臨時文件
                Cookie //表示Cookie
        }

        public class RASDisplay
        {
                [DllImport("wininet.dll", CharSet = CharSet.Auto)]
                public static extern bool DeleteUrlCacheEntry(
                DEL_CACHE_TYPE type
                );
                private string m_duration;
                private string m_ConnectionName;
                private string[] m_ConnectionNames;
                private double m_TX;
                private double m_RX;
                private bool m_connected;
                private IntPtr m_ConnectedRasHandle;

                RasStats status = new RasStats();
                public RASDisplay()
                {
                        m_connected = true;
                        RAS lpras = new RAS();
                        RASCONN lprasConn = new RASCONN();

                        lprasConn.dwSize = Marshal.SizeOf(typeof(RASCONN));
                        lprasConn.hrasconn = IntPtr.Zero;

                        int lpcb = 0;
                        int lpcConnections = 0;
                        int nRet = 0;
                        lpcb = Marshal.SizeOf(typeof(RASCONN));

                        nRet = RAS.RasEnumConnections(ref lprasConn, ref lpcb, ref
                        lpcConnections);

                        if (nRet != 0)
                        {
                                m_connected = false;
                                return;
                        }

                        if (lpcConnections > 0)
                        {
                                //for (int i = 0; i < lpcConnections; i++) 
                                //{

                                names.dwSize = entryNameSize;
                        m_ConnectedRasHandle = lprasConn.hrasconn;
                        RAS.RasGetConnectionStatistics(lprasConn.hrasconn, stats);

                        m_ConnectionName = lprasConn.szEntryName;

                        int Hours = 0;
                        int Minutes = 0;
                        int Seconds = 0;

                        Hours = ((stats.dwConnectionDuration / 1000) / 3600);
                        Minutes = ((stats.dwConnectionDuration / 1000) / 60) - (Hours * 60);
                        Seconds = ((stats.dwConnectionDuration / 1000)) - (Minutes * 60) - (Hours * 3600);

                        m_duration = Hours + " hours " + Minutes + " minutes " + Seconds + " secs";
                        m_TX = stats.dwBytesXmited;
                        m_RX = stats.dwBytesRcved;
                        //}
                }
                else {
                        m_connected = false;
                        }

                        int lpNames = 1;
                int entryNameSize = 0;
                int lpSize = 0;
                RasEntryName[] names = null;

                entryNameSize = Marshal.SizeOf(typeof(RasEntryName));
                lpSize = lpNames * entryNameSize;

                names = new RasEntryName[lpNames];
                names[0].dwSize = entryNameSize;

                uint retval = RAS.RasEnumEntries(null, null, names, ref lpSize, out lpNames);

                //if we have more than one connection, we need to do it again 
                if (lpNames > 1)
                {
                        names = new RasEntryName[lpNames];
                        for (int i = 0; i < names.Length; i++)
                        {
                                names.dwSize = entryNameSize;
                        }

                        retval = RAS.RasEnumEntries(null, null, names, ref lpSize, out lpNames);

                }
                m_ConnectionNames = new string[names.Length];

                if (lpNames > 0)
                {
                        for (int i = 0; i < names.Length; i++)
                        {
                                m_ConnectionNames = names.szEntryName;
                        }
                }
        }

        public string Duration
        {
                get
                {
                        return m_connected ? m_duration : "";
                }
        }

        public string[] Connections
        {
                get
                {
                        return m_ConnectionNames;
                }
        }

        public double BytesTransmitted
        {
                get
                {
                        return m_connected ? m_TX : 0;
                }
        }
        public double BytesReceived
        {
                get
                {
                        return m_connected ? m_RX : 0;
                }
        }
        public string ConnectionName
        {
                get
                {
                        return m_connected ? m_ConnectionName : "";
                }
        }
        public bool IsConnected
        {
                get
                {
                        return m_connected;
                }
        }

        public int Connect(string Connection)
        {
                int temp = 0;
                uint INTERNET_AUTO_DIAL_UNATTENDED = 2;
                int retVal = RAS.InternetDial(IntPtr.Zero, Connection, INTERNET_AUTO_DIAL_UNATTENDED, ref temp, 0);
                return retVal;
        }
        public void Disconnect()
        {
                RAS.RasHangUp(m_ConnectedRasHandle);
        }
}

調用方法:

RASDisplay ras = new RASDisplay();
ras.Disconnect(); //斷開連接
ras.Connect("ADSL"); //重新撥號