放假了，哎。。。一休息就是這麼多天～～～
開始努力學習了
今天練習使用Callback，在對於卻在dom上出了問題。
首先，下面這個例子是 正確的。
ClientCallbacks.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ClientCallbacks.aspx.cs" Inherits="ClientCallbacks" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" ><head runat="server"> <title>無標題頁</title> <script language="javascript">
function DoSearch()
{
var txtFirstName=document.getElementById("txtUsrName"); CallServer(txtFirstName.value,"");
} function ReceiveServerData(txtUsrInfo) { Results.innerText=txtUsrInfo; } setInterval('DoSearch()',1000);
</script></head><body> <form id="form1" runat="server"> <div> 姓名：<input id="txtUsrName" style="position: static" type="text" /> <br /> <span id="Results" style="background-color:Pink; width:500px;"></span> </div> </form></body></html>ClientCallbacks.aspx.cs
using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Data.SqlClient;public partial class ClientCallbacks : System.Web.UI.Page,ICallbackEventHandler{ protected string txtUsrInfo; protected void Page_Load(object sender, EventArgs e) { string cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "ReceiveServerData", "context"); string callbackScript = "function CallServer(arg,context)" + "{ " + cbReference + " };"; Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "CallServer", callbackScript, true); } //trigger callback event public void RaiseCallbackEvent(string txtFirstName) { if (txtFirstName != null) { SqlConnection conn = new SqlConnection("data source=./SQLEXPRESS;initial catalog=Northwind;user id=sa;password=mssqlfs"); conn.Open(); SqlCommand cmd = new SqlCommand("select EmployeeID,FirstName,City,Address from Employees where FirstName=@FirstName", conn); cmd.Parameters.Add("@FirstName", SqlDbType.NVarChar, 10).Value = txtFirstName; SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { txtUsrInfo = "員工代號：" + dr["EmployeeID"] + " ," + "姓名：" + dr["FirstName"] + " ," + "居住地址：" + dr["City"] + " ," + "地址：" + dr["Address"].ToString().Replace(" ", "") + " ," + "服務器查詢時間：" + DateTime.Now.ToLongTimeString(); } else { if (String.IsNullOrEmpty(txtFirstName)) { txtUsrInfo = "請輸入姓名"; } else { txtUsrInfo = "查無此人!"; } } cmd.Dispose(); dr.Dispose(); conn.Dispose(); } } public string GetCallbackResult() { return txtUsrInfo; }}
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然後，下面這個卻出了小問題。
ClientCallbackSimple.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ClientCallbacksSimple.aspx.cs" Inherits="ClientCallbacksSimple" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" ><head runat="server"> <title>cccc</title> <script type="text/javascript"> function OnCallback(txtUsrInfo,context) { alert(txtUsrInfo); Results.innerText=txtUsrInfo; } </script></head><body> <form id="form1" runat="server"> <div> name:<input id="txtUsrName" style="position: static" type="text" /> <input id="btnCallback" style="position: static" type="button" value="button" onclick="<%=ClientScript.GetCallbackEventReference(this,"document.form1.txtUsrName.value","OnCallback",null) %>" /><br /> <div id="Results"></div> </div> </form></body></html>ClientCallbackSimple.aspx.cs
using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Data.SqlClient;public partial class ClientCallbacksSimple : System.Web.UI.Page,System.Web.UI.ICallbackEventHandler{ protected string txtUsrInfo; protected void Page_Load(object sender, EventArgs e) { } //trigger callback event public void RaiseCallbackEvent(string txtFirstName) { if (txtFirstName != null) { SqlConnection conn = new SqlConnection("data source=./SQLEXPRESS;initial catalog=Northwind;user id=sa;password=mssqlfs"); conn.Open(); SqlCommand cmd = new SqlCommand("select EmployeeID,FirstName,City,Address from Employees where FirstName=@FirstName", conn); cmd.Parameters.Add("@FirstName", SqlDbType.NVarChar, 10).Value = txtFirstName; SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { txtUsrInfo = "員工代號：" + dr["EmployeeID"] + " ," + "姓名：" + dr["FirstName"] + " ," + "居住地址：" + dr["City"] + " ," + "地址：" + dr["Address"].ToString().Replace(" ", "") + " ," + "服務器查詢時間：" + DateTime.Now.ToLongTimeString(); } else { if (String.IsNullOrEmpty(txtFirstName)) { txtUsrInfo = "請輸入姓名"; } else { txtUsrInfo = "查無此人!"; } } cmd.Dispose(); dr.Dispose(); conn.Dispose(); } } public string GetCallbackResult() { return txtUsrInfo; }}用firebug顯示出的錯誤是：
Results is not defined
WebForm_CallbackComplete()WebResource.axd (line 162)
Results.innerText=txtUsrInfo;
ClientCallbacksSi... (line 13)|
async
|
false |
|
context
|
null |
|
errorCallback
|
null |
|
xmlRequest
|
XMLHttpRequest |
|
eventCallback
|
OnCallback(txtUsrInfo, context) |
但是我定義了啊。。。而且aspx文件和第一個正常顯示的網頁（ClientCallbacks.aspx）幾乎一樣，關於
Results.innerText語句並沒有變化。
問題解決：
我給VS設的默認瀏覽器是FIREFOX，突然我想會不會是瀏覽器的問題，
我用IE打開後，果然，正確顯示。。。