<form id="viewReportForm" name="viewReportForm" method="post"  runat="server">
<input type="button" value="" id="reportSearch" name="reportSearch" value="查询报表" class="rptSearch" onclick="OnReportSearchClick()" />
<iframe id="frmViewerCrReport"  />
</form>

有两个页面。 一个是View.aspx 另一个是"ShowCrystalReportViewer.aspx

 //查询报表
  function OnReportSearchClick()
   {
                            viewReportForm.method = "post";
                            viewReportForm.action = location.href;
                            viewReportForm.submit();
    //提供数据到IFrame 中
                            viewReportForm.method = "post";
                            viewReportForm.target = "frmViewerCrReport";
                            viewReportForm.action = "ShowCrystalReportViewer.aspx?t="+ Math.random();
                            viewReportForm.submit();

  }

说明： "ShowCrystalReportViewer.aspx  接收View.aspx  post过去的参数， 根据参数来展示水晶报表

问题： 点击 查询报表按钮时， 先候会触发 View.aspx的Page_Load和ShowCrystalReportViewer.aspx的Page_Load事件。

我在页基类的 protected override void Render(HtmlTextWriter writer)
           {

            StringWriter stringWriter = new StringWriter();
            HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);

            base.Render(htmlWriter);
            string html = stringWriter.ToString();

           #region ViewState

            int startPoint = html.IndexOf("<input type=\"hidden\" name=\"__VIEWSTATE\"");
            if (startPoint >= 0)
            {
                int endPoint = html.IndexOf("/>", startPoint) + 2;
                string viewStateInput = html.Substring(startPoint, endPoint - startPoint);
                html = html.Remove(startPoint, endPoint - startPoint);
                int formEndStart = html.IndexOf("</form>", startPoint);
                if (formEndStart >= 0)
                {
                    html = html.Insert(formEndStart, viewStateInput);
                }
            }

            #endregion

            #region 辅助输出信息

            StringBuilder sb = new StringBuilder("");
            foreach (string sKey in m_dicHiddens.Keys)
            {
                sb.AppendFormat("<input type=\"hidden\" id=\"{0}\" name=\"{0}\" value=\"{1}\" />\n", sKey, m_dicHiddens[sKey]);
            }

            if (sb.Length >= 1)
            {
                int nLastIndex = html.LastIndexOf("</form>");
                if (nLastIndex == -1)
                {
                    nLastIndex = html.LastIndexOf("</body>");
                }

                html = html.Insert(nLastIndex, "\n" + sb.ToString());
            }

            //脚本
            if (m_sbAppendScriptToEndBody.Length > 0)
            {
                sb = new StringBuilder("");
                sb.AppendLine("<script type=\"text/javascript\">");
                sb.AppendFormat(" {0}", m_sbAppendScriptToEndBody.ToString());
                sb.AppendLine("</script>");

                int nLastIndex = html.LastIndexOf("</body>");

                html = html.Insert(nLastIndex, "\n" + sb.ToString());
            }

            #endregion

            writer.Write(html);  // 这里我监测到会触发两次。首先是View.aspx  其次是ShowCrystalReportViewer.aspx

                                 // 比如 View.aspx触发时。生成<h>新的</h>
                                 // 可真正生成的页面却还是上次没触发的页面数据。
           }