HttpContext.Current 属性 ---为当前 HTTP 请求获取或设置 HttpContext 对象。

protected void Page_Load(object sender, EventArgs e)
{
    HttpContext context = HttpContext.Current;
    Response.Write("<p>HttpContext.Current Example:</p>");

    // Add three custom exceptions.
    context.AddError(new Exception("New Exception #1"));
    context.AddError(new Exception("New Exception #2"));
    context.AddError(new Exception("New Exception #3"));

    // Capture all the new Exceptions in an array.
    Exception[] errs = context.AllErrors;

    foreach (Exception ex in errs)
    {
        Response.Write("<p>" + Server.HtmlEncode(ex.ToString()) + "</p>");
    }

    // Clear the exceptions so ASP.NET won't handle them.
    context.ClearError();
}