ASP.NET(C#)返回上一页(后退)代码

//第一种protected void Page_Load(object sender, EventArgs e){    if (!IsPostBack)    {        ViewState["BackUrl"] = Request.UrlReferrer.ToString();    }}/// <summary>/// 返回按钮点击事件/// </summary>protected void Button1_Click(object sender, EventArgs e){    Response.Redirect(ViewState["BackUrl"].ToString());}

//第二种,其中，history.go(-2)，要写为-2，因在按钮事件触发前，已刷新一次页面，所以应是-2Response.Write("<script language=javascript>history.go(-2);</script>");

//第三种ScriptManager.RegisterStartupScript(this,this.GetType(),"E", "<script>history.go(-2);</script>",false);