ICallbackHandler实现GridView无刷新实时更新
GridView的数据显示一般是固定的,假如要像Ajax那样实现GridView数据动态更新而不刷新页面,就有些难度了.客户提出的需求,没办法,也得去试着想办法实现.
涉及到Asp.Net事件机制的实现"_doPostback".Asp.Net的底层封装了XMLHttpRequest异步请求对象.在WebResource.axd中可以查看到这些封装的JavaScript.对于页面的异步请求,我们需要实现ICallbackEventHandler接口,并显示实现其中的GetCallbackResult()和RaiseCallbackEvent()这两个方法.废话不多少,假如了解Asp.Net机制的话一看就明白了.代码就贴在下面:
public partial class upload_MixInfo : System.Web.UI.Page,System.Web.UI.ICallbackEventHandler
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack) { GetAllUser();
} string cbReference = Page.ClientScript.GetCallbackEventReference(Page, "", "Refresh", ""); btnGet.Attributes.Add("onclick",cbReference); string script=""; script+="<script>\r\n"; script+="function Refresh(DataFromServer){\r\n"; script+="document.getElementById('Result').innerHTML=DataFromServer;\r\n"; script+="}\r\n</script>\r\n"; Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "Refresh", script); } public string GetCallbackResult() { return RenderControl(Test); } public void RaiseCallbackEvent(string eventArgument) { GetAllUser(); } private string RenderControl(Control c) { StringWriter writer1 = new StringWriter(CultureInfo.InvariantCulture); HtmlTextWriter writer = new HtmlTextWriter(writer1); c.RenderControl(writer); writer.Flush(); writer.Close(); return writer1.ToString(); } protected void GetAllUser() { string sql = @"(Transform Sum(Nums)select [Users].[UserName] as 地区负责人 from (([Users] left join [User_Type] on [Users].UserId=[User_Type].UserId) left join [Type] on [User_Type].TypeId=[Type].TypeId) GROUP BY [Users].UserNamePIVOT [Type].TypeId)"; OleDbConnection con = DBConn.NewConnection(); OleDbCommand cmd = new OleDbCommand(sql, con); OleDbDataAdapter adapter = new OleDbDataAdapter(cmd); DataTable dt=new DataTable(); adapter.Fill(dt); dt.Columns.Remove(dt.Columns[1]); sql = "select * from [Type]"; cmd.CommandText = sql; DataTable t = new DataTable(); adapter=new OleDbDataAdapter(cmd); adapter.Fill(t); DBConn.ResourceDispose(cmd); for (int i = 0; i < t.Rows.Count; i++) { for (int j = 0; j < dt.Columns.Count; j++) { if (t.Rows[i]["TypeId"].ToString() == ((DataColumn)dt.Columns[j]).ColumnName) { dt.Columns[j].ColumnName = t.Rows[i]["TypeName"].ToString(); } } } Test.DataSource = dt; Test.DataBind(); }
}<body> <form id="form1" runat="server"> <input type="button" runat="server" id="btnGet" value="Get" style="display:none"/> <div id="Result"> <asp:GridView ID="Test" runat="server" CellPadding="4" ForeColor="#333333"> <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" /> <RowStyle BackColor="#EFF3FB" /> <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" /> <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" /> <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" /> <EditRowStyle BackColor="#2461BF" /> <AlternatingRowStyle BackColor="White" /> </asp:GridView> </div> </form> <script type="text/javascript">function btnclick(){document.getElementById("btnGet").click();}setInterval("btnclick()",10000);</script></body>