在ASP.NET中实现404的最佳方法

 <customErrors mode="On" defaultRedirect="Error404.aspx">
   <error statusCode="404" redirect="Error404.aspx"/>
  </customErrors>
</system.web>

protected void Application_Error(object sender, EventArgs e)
{
    Exception ex = Server.GetLastError();
    HttpException httpEx = ex as HttpException;
    if (httpEx != null && httpEx.GetHttpCode() == 404)
    {
        Server.ClearError();
        Response.Redirect("Error404.aspx");
    }
}