通过测试webBrowser与IE缓存和Cookie都存放在Local Settings\Temporary Internet Files，我们可以直接调用IE API进行清除
解决方案1：
public enum ShowCommands : int
{
SW_HIDE = ,
SW_SHOWNORMAL = ,
SW_NORMAL = ,
SW_SHOWMINIMIZED = ,
SW_SHOWMAXIMIZED = ,
SW_MAXIMIZE = ,
SW_SHOWNOACTIVATE = ,
SW_SHOW = ,
SW_MINIMIZE = ,
SW_SHOWMINNOACTIVE = ,
SW_SHOWNA = ,
SW_RESTORE = ,
SW_SHOWDEFAULT = ,
SW_FORCEMINIMIZE = ,
SW_MAX =
}[DllImport("shell32.dll")]
static extern IntPtr ShellExecute( IntPtr hwnd, string lpOperation, string lpFile, string lpParameters, string lpDirectory, ShowCommands nShowCmd);
//清除IE临时文件
ShellExecute(IntPtr.Zero, "open", "rundll32.exe", "InetCpl.cpl,ClearMyTracksByProcess 255", "", ShowCommands.SW_HIDE)其中ClearMyTracksByProcess 可进行选择设置 ：
Temporary Internet Files （Internet临时文件）
RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 8
Cookies
RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 2
History (历史记录)
RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 1
Form. Data （表单数据）
RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 16
Passwords (密码）
RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 32
Delete All （全部删除）
RunDll32.exe InetCpl.cpl,ClearMyTracksByProcess 255
缺点：在Webbrowser 在不关闭的情况下无法清除cookie
解决方案2：
//清除Session所需要调用的函数
[ DllImport ("wininet.dll" , SetLastError = true )]
private static extern bool InternetSetOption ( IntPtr hInternet , int dwOption, IntPtr lpBuffer , int lpdwBufferLength );
//清空session
public void ResetSession()
{
//Session的选项ID为42
InternetSetOption ( IntPtr.Zero , , IntPtr.Zero , );
}
//清空cookie
public void ResetCookie()
{
if (c_web.Document != null )
{
c_web.Document.Cookie.Remove ( , c_web.Document.Cookie.Count() - ); }
string [] theCookies = System.IO.Directory.GetFiles ( Environment.GetFolderPath (Environment.SpecialFolder.Cookies ));
foreach (string currentFile in theCookies )
{
try
{
System.IO.File.Delete (currentFile );
}
catch (Exception ex)
{
}
}
}
缺点：需要程序取得管理员权限
解决方案3：
利用 webBrowser 执行清楚cookie的js代码
this._webBrowser.Navigate("javascript:void((function(){var a,b,c,e,f;f=0;a=document.cookie.split('; ');for(e=0;e<a.length&&a[e];e++){f++;for(b='.'+location.host;b;b=b.replace(/^(?:%5C.|[^%5C.]+)/,'')){for(c=location.pathname;c;c=c.replace(/.$/,'')){document.cookie=(a[e]+'; domain='+b+'; path='+c+'; expires='+new Date((new Date()).getTime()-1e11).toGMTString());}}}})())");缺点：在某些运行环境中会报“无法下载”的错，至于原因目前还没找到