使用win api 返回CookieContainer

   1: [DllImport("wininet.dll", SetLastError = true)]

   2: public static extern bool InternetGetCookieEx(

   3:   string url, 

   4:   string cookieName, 

   5:   StringBuilder cookieData, 

   6:   ref int size,

   7:   Int32  dwFlags,

   8:   IntPtr  lpReserved);

   9:  

  10:  private const Int32 InternetCookieHttponly = 0x2000;

/// <summary>
/// Gets the URI cookie container.
/// </summary>
/// <param name="uri">The URI.</param>
/// <returns></returns>
public static CookieContainer GetUriCookieContainer(Uri uri)
{
    CookieContainer cookies = null;
    // Determine the size of the cookie
    int datasize = 8192 * 16;
    StringBuilder cookieData = new StringBuilder(datasize);
    if (!InternetGetCookieEx(uri.ToString(), null, cookieData, ref datasize, InternetCookieHttponly, IntPtr.Zero))
    {
        if (datasize < 0)
            return null;
        // Allocate stringbuilder large enough to hold the cookie
        cookieData = new StringBuilder(datasize);
        if (!InternetGetCookieEx(
            uri.ToString(),
            null, cookieData,
            ref datasize,
            InternetCookieHttponly,
            IntPtr.Zero))
            return null;
    }
    if (cookieData.Length > 0)
    {
        cookies = new CookieContainer();
        cookies.SetCookies(uri, cookieData.ToString().Replace(';', ','));
    }
    return cookies;
}
private const int INTERNET_OPTION_END_BROWSER_SESSION = 42;

[DllImport("wininet.dll", SetLastError = true)]
private static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int lpdwBufferLength);

public static void ClearCookie()
{
    InternetSetOption(IntPtr.Zero, INTERNET_OPTION_END_BROWSER_SESSION, IntPtr.Zero, 0);
}