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简单的实现ASP页面回调技术的示例

2014-09-25 08:45 204 查看

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">

<html xmlns="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;

}

}

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