C#设置IE代理及遇到问题的解决方案

　　起初使用的方法是修改完一次代理之后就不能继续修改，需要重新启动一次进程才可以，最初代码是：

 private void ShowProxyInfo()
        {
            if (!GetProxyStatus())
            {
                lblInitInfo.Text = "代理未启用：";
            }
            else
            {
                lblInitInfo.Text = "当前使用的代理是：" + GetProxyServer();
            }

        }

        private void InitProxyData()
        {
            List<string> proxyList = new List<string>{
               "http://web-proxy.cup.hp.com:8080","http://proxy.compaq.com:8080"
           };
            combProxyList.DataSource = proxyList;
            combProxyList.SelectedIndex = 0;
        }
        public void SetProxy(string proxy)
        {
            //打开注册表 
            //RegistryKey regKey = Registry.CurrentUser;
            //string SubKeyPath = "Software\Microsoft\Windows\CurrentVersion\Internet Settings";
            //RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);             //更改健值，设置代理， 
            //optionKey.SetValue("ProxyEnable", 1);
            //optionKey.SetValue("ProxyServer", proxy);

            ////激活代理设置【用于即使IE没有关闭也能更新当前打开的IE中的代理设置。】   
            //InternetSetOption(0, 39, IntPtr.Zero, 0);
            //InternetSetOption(0, 37, IntPtr.Zero, 0);
            //regKey.Flush(); //刷新注册表  
            //regKey.Close();
            //ShowProxyInfo();

            using (RegistryKey regKey = Registry.CurrentUser)
            {
                string SubKeyPath = "Software\Microsoft\Windows\CurrentVersion\Internet Settings";
                RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);             //更改健值，设置代理
                optionKey.SetValue("ProxyEnable", 1);
                optionKey.SetValue("ProxyServer", proxy);
                //激活代理设置【用于即使IE没有关闭也能更新当前打开的IE中的代理设置。】   
                InternetSetOption(0, 39, IntPtr.Zero, 0);
                InternetSetOption(0, 37, IntPtr.Zero, 0);
                regKey.Flush(); //刷新注册表  
                ShowProxyInfo();
            }

        }

        public void DisableProxy()
        {
            //打开注册表 
            RegistryKey regKey = Registry.CurrentUser;
            string SubKeyPath = "Software\Microsoft\Windows\CurrentVersion\Internet Settings";
            RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);             //更改健值，设置代理， 
            optionKey.SetValue("ProxyEnable", 0);
            regKey.Flush(); //刷新注册表  
            InternetSetOption(0, 39, IntPtr.Zero, 0);
            InternetSetOption(0, 37, IntPtr.Zero, 0);
            regKey.Close();
            ShowProxyInfo();
        }

        [DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto,
          EntryPoint = "InternetSetOption",
          CallingConvention = CallingConvention.StdCall)]
        public static extern bool InternetSetOption(
        int hInternet, int dmOption, IntPtr lpBuffer, int dwBufferLength);

        private void btnSetProxy_Click(object sender, EventArgs e)
        {
            string proxyStr = combProxyList.Text.Trim();
            SetProxy(proxyStr);
            var currentProxy = GetProxyServer();
            if (currentProxy == proxyStr && GetProxyStatus())
            {
                lblInfo.Text = "设置代理：" + proxyStr + "成功！";
                lblInfo.ForeColor = Color.Green;
            }
            else
            {
                if (!GetProxyStatus())
                {
                    lblInfo.Text = "设置代理：" + proxyStr + "代理未启用！";

                }
                else
                {
                    lblInfo.Text = "设置代理：" + proxyStr + "失败，正在使用" + currentProxy + "代理，请重试！";

                }
                lblInfo.ForeColor = Color.Red;
            }
            ShowProxyInfo();

        }

        /// <summary>
        /// 获取正在使用的代理
        /// </summary>
        /// <returns></returns>
        private string GetProxyServer()
        {
            //打开注册表 
            RegistryKey regKey = Registry.CurrentUser;
            string SubKeyPath = "Software\Microsoft\Windows\CurrentVersion\Internet Settings";
            RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);             //更改健值，设置代理， 
            string actualProxy = optionKey.GetValue("ProxyServer").ToString();
            regKey.Close();
            return actualProxy;
        }

        private bool GetProxyStatus()
        {
            //打开注册表 
            RegistryKey regKey = Registry.CurrentUser;
            string SubKeyPath = "Software\Microsoft\Windows\CurrentVersion\Internet Settings";
            RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);             //更改健值，设置代理， 
            int actualProxyStatus = Convert.ToInt32(optionKey.GetValue("ProxyEnable"));
            regKey.Close();
            return actualProxyStatus == 1 ? true : false;
        }

        //成功返回true，错误返回false  
        public Boolean prcessBaidu()
        {
            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create("http://www.163.com");
            myRequest.Method = "POST"; //采用post方式提交访问163主页 // Get response      
            try//当无法访问163网站时，下面的对象会有错误产生，所以用try..catch处理掉这些异常     
            {
                Stream newStream = myRequest.GetRequestStream();//获取请求流     // Send the data.         
                newStream.Close();//关闭请求流 
                HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();//获取应答对象    
                StreamReader reader = new StreamReader(myResponse.GetResponseStream());//获取应答流     
                string content = reader.ReadToEnd();//将流对象读取到string 中 
                if (content.IndexOf("http://reg.163.com") > -1)//如果访问网站成功，则网页中包含置顶的关键字符串“http://reg.163.com”表示访问网页成功    
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (Exception ex)
            {
                return false;
            }
            return false;
        }

        private void btnDisableProxy_Click(object sender, EventArgs e)
        {
            DisableProxy();

            if (!GetProxyStatus())
            {
                lblInfo.Text = "取消代理完成！";
                lblInfo.ForeColor = Color.Green;
            }
            else
            {
                lblInfo.Text = "取消失败，正在使用代理" + GetProxyServer();
                lblInfo.ForeColor = Color.Red;
            }
            ShowProxyInfo();
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void btnTestProxy_Click(object sender, EventArgs e)
        {
            string proxyStr = combProxyList.SelectedText;
            SetProxy(proxyStr);
            if (prcessBaidu())
            {
                MessageBox.Show("代理可以正常访问。");
            }
            else
            {
                MessageBox.Show("目前无法使用代理！");
            }
            ShowProxyInfo();
        }

　　有网友的结果是说在window7下， 在一个进程中， 设置和取消不能都执行，---- 要么设置，要么取消。 但如果第一次运行时，只进行设置代理，退出后再进运行，只进行取消，这是没有问题的。简单说说他给出的解决方案：每次设置或取消代理时，都新建一个进程，在新的进程中处理，处理完之后关掉进程。参考http://blog.csdn.net/debug__boy/article/details/8432879提供新的解决方案，国外大神的文章http://huddledmasses.org/setting-windows-internet-connection-proxy-from-c/：代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace IEProxyManagment
{
   
    public class IEProxySetting
    {
        public static bool UnsetProxy()
        {
            return SetProxy(null, null);
        }
        public static bool SetProxy(string strProxy)
        {
            return SetProxy(strProxy, null);
        }

        public static bool SetProxy(string strProxy, string exceptions)
        {
            InternetPerConnOptionList list = new InternetPerConnOptionList();

            int optionCount = string.IsNullOrEmpty(strProxy) ? 1 : (string.IsNullOrEmpty(exceptions) ? 2 : 3);
            InternetConnectionOption[] options = new InternetConnectionOption[optionCount];
            // USE a proxy server ...
            options[0].m_Option = PerConnOption.INTERNET_PER_CONN_FLAGS;
            options[0].m_Value.m_Int = (int)((optionCount < 2) ? PerConnFlags.PROXY_TYPE_DIRECT : (PerConnFlags.PROXY_TYPE_DIRECT | PerConnFlags.PROXY_TYPE_PROXY));
            // use THIS proxy server
            if (optionCount > 1)
            {
                options[1].m_Option = PerConnOption.INTERNET_PER_CONN_PROXY_SERVER;
                options[1].m_Value.m_StringPtr = Marshal.StringToHGlobalAuto(strProxy);
                // except for these addresses ...
                if (optionCount > 2)
                {
                    options[2].m_Option = PerConnOption.INTERNET_PER_CONN_PROXY_BYPASS;
                    options[2].m_Value.m_StringPtr = Marshal.StringToHGlobalAuto(exceptions);
                }
            }

            // default stuff
            list.dwSize = Marshal.SizeOf(list);
            list.szConnection = IntPtr.Zero;
            list.dwOptionCount = options.Length;
            list.dwOptionError = 0;


            int optSize = Marshal.SizeOf(typeof(InternetConnectionOption));
            // make a pointer out of all that ...
            IntPtr optionsPtr = Marshal.AllocCoTaskMem(optSize * options.Length);
            // copy the array over into that spot in memory ...
            for (int i = 0; i < options.Length; ++i)
            {
                IntPtr opt = new IntPtr(optionsPtr.ToInt32() + (i * optSize));
                Marshal.StructureToPtr(options[i], opt, false);
            }

            list.options = optionsPtr;

            // and then make a pointer out of the whole list
            IntPtr ipcoListPtr = Marshal.AllocCoTaskMem((Int32)list.dwSize);
            Marshal.StructureToPtr(list, ipcoListPtr, false);

            // and finally, call the API method!
            int returnvalue = NativeMethods.InternetSetOption(IntPtr.Zero,
               InternetOption.INTERNET_OPTION_PER_CONNECTION_OPTION,
               ipcoListPtr, list.dwSize) ? -1 : 0;
            if (returnvalue == 0)
            {  // get the error codes, they might be helpful
                returnvalue = Marshal.GetLastWin32Error();
            }
            // FREE the data ASAP
            Marshal.FreeCoTaskMem(optionsPtr);
            Marshal.FreeCoTaskMem(ipcoListPtr);
            if (returnvalue > 0)
            {  // throw the error codes, they might be helpful
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }

            return (returnvalue < 0);
        }
    }

    #region WinInet structures
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct InternetPerConnOptionList
    {
        public int dwSize;               // size of the INTERNET_PER_CONN_OPTION_LIST struct
        public IntPtr szConnection;         // connection name to set/query options
        public int dwOptionCount;        // number of options to set/query
        public int dwOptionError;           // on error, which option failed
        //[MarshalAs(UnmanagedType.)]
        public IntPtr options;
    };

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct InternetConnectionOption
    {
        static readonly int Size;
        public PerConnOption m_Option;
        public InternetConnectionOptionValue m_Value;
        static InternetConnectionOption()
        {
            InternetConnectionOption.Size = Marshal.SizeOf(typeof(InternetConnectionOption));
        }

        // Nested Types
        [StructLayout(LayoutKind.Explicit)]
        public struct InternetConnectionOptionValue
        {
            // Fields
            [FieldOffset(0)]
            public System.Runtime.InteropServices.ComTypes.FILETIME m_FileTime;
            [FieldOffset(0)]
            public int m_Int;
            [FieldOffset(0)]
            public IntPtr m_StringPtr;
        }
    }
    #endregion

    #region WinInet enums
    //
    // options manifests for Internet{Query|Set}Option
    //
    public enum InternetOption : uint
    {
        INTERNET_OPTION_PER_CONNECTION_OPTION = 75
    }

    //
    // Options used in INTERNET_PER_CONN_OPTON struct
    //
    public enum PerConnOption
    {
        INTERNET_PER_CONN_FLAGS = 1, // Sets or retrieves the connection type. The Value member will contain one or more of the values from PerConnFlags 
        INTERNET_PER_CONN_PROXY_SERVER = 2, // Sets or retrieves a string containing the proxy servers.  
        INTERNET_PER_CONN_PROXY_BYPASS = 3, // Sets or retrieves a string containing the URLs that do not use the proxy server.  
        INTERNET_PER_CONN_AUTOCONFIG_URL = 4//, // Sets or retrieves a string containing the URL to the automatic configuration script.  

    }

    //
    // PER_CONN_FLAGS
    //
    [Flags]
    public enum PerConnFlags
    {
        PROXY_TYPE_DIRECT = 0x00000001,  // direct to net
        PROXY_TYPE_PROXY = 0x00000002,  // via named proxy
        PROXY_TYPE_AUTO_PROXY_URL = 0x00000004,  // autoproxy URL
        PROXY_TYPE_AUTO_DETECT = 0x00000008   // use autoproxy detection
    }
    #endregion

    internal static class NativeMethods
    {
        [DllImport("WinInet.dll", SetLastError = true, CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool InternetSetOption(IntPtr hInternet, InternetOption dwOption, IntPtr lpBuffer, int dwBufferLength);
    }
}

　　UnsetProxy方法为取消代理设置，SetProxy(string strProxy, string exceptions)方法为设置指定代理。

　　以下是我做的一个可以动态修改代理的Winform程序，备忘下载。