简单的实现ASP页面回调技术的示例

我会带着你远行 2024-02-17 15:04 62阅读 0赞

前台代码：

<%@ Page Language="C\#" CodeFile="Default.aspx.cs" Inherits="\_Default" %>  
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "[http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd][http_www.w3.org_TR_xhtml1_DTD_xhtml1-transitional.dtd]">  
<html xmlns="[http://www.w3.org/1999/xhtml][http_www.w3.org_1999_xhtml]" >  
<head id="Head1" runat="server">  
<title>回调练习</title>  
<script type = "text/javascript" language ="javascript" >  
function CallServerFunction(Num2)  
\{  
//Arg是传向后台方法RaiseCallbackEvent()的参数,这里将操作符操作数一块传过去  
Arg = Num2.value;  
//获取一个客户端函数的引用；调用该函数时，将启动一个对服务器端事件的客户端回调  
<%= ClientScript.GetCallbackEventReference(this,"Arg","ReceiveServerData","null") %>  
\}  
//接收回调后台传过来的结果数据,该函数名为GetCallbackEventReference()的第三个参数  
function ReceiveServerData(result)  
\{  
//js里面,必须用Label的innerText属性,用Text属性不会产生任何效果  
lblShow.innerText = result;  
\}  
</script>  
</head>  
<body>  
<form id="form1" runat="server">  
<div>  
<input type = "text" id="Num2" onblur = "CallServerFunction(Num2)"/>  
<%--调用回调函数的控件必须是HTML控件,不能为服务端控件--%>  
<input type = "text" id="Text1"  />  
<asp:Label ID="lblShow" runat="server" Text="show"></asp:Label>  
</div>  
</form>  
</body>  
</html>

\--------------------------------------------------------------------------------------------------

后台代码：

using System;  
using System.Data;  
using System.Configuration;  
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;

//必须声明System.Web.UI.ICallbackEventHandler接口  
public partial class \_Default : System.Web.UI.Page, System.Web.UI.ICallbackEventHandler  
\{  
//定义一个回调的返回值  
private string result;  
protected void Page\_Load(object sender, EventArgs e)  
\{

/// <summary>  
/// 该方法是回调执行的方法，根据参数在这个方法中处理回调的内容,该方法没有返回值  
/// </summary>  
/// <param name="eventArgument">此参数是从客户端传过来的</param>  
public void RaiseCallbackEvent(string eventArgument)  
\{  
SqlConnectionStringBuilder conBuilder = new SqlConnectionStringBuilder();  
conBuilder.DataSource = "(local)";  
conBuilder.InitialCatalog = "pubs";  
conBuilder.IntegratedSecurity = true;  //Windows身份验证就是true,帐号和密码的就是false  
conBuilder.UserID = "false";  
conBuilder.Password = "false";  
string conStr = conBuilder.ToString();  
SqlConnection connect = new SqlConnection(conStr);  
connect.Open();  
Boolean judge = true;  
SqlCommand command = new SqlCommand("select \* from Table\_1;", connect);  
SqlDataReader read = command.ExecuteReader(CommandBehavior.CloseConnection);  
while (read.Read())  
\{  
if (eventArgument == read.GetString(0))  
\{  
judge = false;  
break;  
\}  
else  
judge = true;  
\}  
if (judge == false)  
\{  
result = eventArgument + "该用户不能被注册！";  
\}  
else  
result = eventArgument + "该用户可以被注册！";  
read.Close();  
\}

/// <summary>  
/// 该方法是返回回调的结果给客户端  
/// </summary>  
/// <returns></returns>  
public string GetCallbackResult()  
\{  
return result;  
\}  
\}

[http_www.w3.org_TR_xhtml1_DTD_xhtml1-transitional.dtd]: http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd
[http_www.w3.org_1999_xhtml]: http://www.w3.org/1999/xhtml