Asp.net回调技术Callback学习

浏览数：95 / 时间：2015年06月09日

.aspx:

Html代码

<%@ Page Language="C#" AutoEventWireup="true" 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 runat="server">
<title>无标题页</title>
<script type="text/javascript">
//向服务器传递参数
function DoSearch(){
var firstName=document.getElementById("TextBox1").value;
CallServer(firstName,"");
}
//得到服务器的数据
function ReceiveServerData(txtUserInfo){
Results.innerHTML=txtUserInfo;
}
//设置每1秒执行一次
setInterval("DoSearch()",1000);
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
姓名:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<br />
<span id="Results" style=" width:500px;"></span>
</div>
</form>
</body>
</html>

.aspx.cs

C#代码

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
{
protected string txtUserInfo;
protected void Page_Load(object sender, EventArgs e)
{
//获取一个对客户端函数的引用
string cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "ReceiveServerData", "context");
//动态注册回调函数
string callbackScript = "function CallServer(arg,context)" + "{" + cbReference + "};";
//引发callbackScript
Page.ClientScript.RegisterStartupScript(this.GetType(), "CallServer", callbackScript, true);
}
//引发Callback事件处理
public void RaiseCallbackEvent(string txtFirstName)
{
if (txtFirstName != null)
{
String connString = System.Configuration.ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString();
SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn);
comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName;
SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);
if (reader.Read())
{
txtUserInfo = "员工编号:" + reader["id"].ToString() + "<br>";
txtUserInfo += "员工姓名:" + reader["name"].ToString() + "<br>";
txtUserInfo += "地址:" + reader["address"].ToString() + "<br>";
txtUserInfo += "服务器查询时间:" + DateTime.Now.ToString();
}
else
{
if (string.IsNullOrEmpty(txtFirstName))
{
txtUserInfo = "请输入姓名";
}
else
{
txtUserInfo = "查无此人";
}
}
comm.Dispose();
reader.Dispose();
conn.Dispose();
}
}
//得到回调的结果,返回给客户端
public string GetCallbackResult()
{
return txtUserInfo;
}
}

简化版(偷懒一下):

Html代码

<%@ Page Language="C#" AutoEventWireup="true" 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 runat="server">
<title>无标题页</title>
<script type="text/javascript">
function OnCallBack(txtUserInfo,context){
Results.innerHTML=txtUserInfo;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
姓名:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<input id="Button2" type="button" value="button"
onclick="<%=Page.ClientScript.GetCallbackEventReference(this, "document.getElementById(‘TextBox1‘).value", "OnCallBack",null)%>" />
<br />
<span id="Results" style="pink; width: 500;"></span>
</div>
</form>
</body>
</html>

.aspx.cs

C#代码

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using System.Text;
public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
{
protected StringBuilder txtUserInfo;
protected void Page_Load(object sender, EventArgs e)
{
}
public string GetCallbackResult()
{
return txtUserInfo.ToString();
}
public void RaiseCallbackEvent(string txtFirstName)
{
txtUserInfo = new StringBuilder();
String connString = ConfigurationManager.ConnectionStrings["sqlserver2008"].ToString();
SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand comm = new SqlCommand("select * from zzx where [name]=@name", conn);
comm.Parameters.Add("@name", SqlDbType.VarChar).Value = txtFirstName;
SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);
if (reader.Read())
{
txtUserInfo.Append("员工编号:" + reader["id"].ToString() + "<br>");
txtUserInfo.Append("员工姓名:" + reader["name"].ToString() + "<br>");
txtUserInfo.Append("地址:" + reader["address"].ToString() + "<br>");
txtUserInfo.Append("查询时间:" + DateTime.Now.ToString());
}
else
{
if (txtFirstName == string.Empty)
{
txtUserInfo.Append("请输入姓名");
}
else
{
txtUserInfo.Append("查无此人");
}
reader.Dispose();
comm.Dispose();
conn.Dispose();
}
}
}

示例3:

Html代码

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>
<!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>无标题页</title>
<script type="text/javascript">
//客户端执行的方法
//下面的方法是接收并处理服务器方法返回的结果
function Success(args,context){
message.innerHTML=args;
}
//下面的方式是当接收服务器方法处理的结果发生异常时调用的方法
function Error(){
message.innerHTML="发生了异常!";
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
用户名:<input type="text" id="txtUserName" onblur="CallServerMethod(txtUserName.value,null)" />
<span id="message"></span>
<br />
密码:<input type="password" size="10" maxlength="20" id="txtPwd" />
</div>
</form>
</body>
</html>

C#代码

public partial class Default3 : System.Web.UI.Page,ICallbackEventHandler //实现ICallbackEventHandler接口
{
String result = String.Empty;
protected void Page_Load(object sender, EventArgs e)
{
//获取当前页的ClientScriptManager的引用
ClientScriptManager csm = Page.ClientScript;
/*获取回调的引用.会在客户端生成WebForm_DoCallback方法,
* 调用它来达到异步调用.这个方法是微软写的方法,会被发送
到客户端*/
/*注意这里的"Success"和Error两个字符串分别是客户端代码中
*定义的两个javascript函数*/
//下面的方法最后一个参数的意义:true表示执行异步回调,false标志执行同步回调
String reference = csm.GetCallbackEventReference(this, "args", "Success", "", "Error", true);
String callbackScript = "function CallServerMethod(args,context){\n"+
reference+";\n }";
//向当前页面注册javascript脚本代码
csm.RegisterClientScriptBlock(this.GetType(), "CallServerMethod",callbackScript,true);
}
#region ICallbackEventHandler 成员
/// <summary>
/// 返回回调方法执行结果的方法
/// </summary>
public string GetCallbackResult()
{
return result;
}
/// <summary>
/// 在服务器端运行回调方法
/// </summary>
public void RaiseCallbackEvent(string eventArgument)
{
if (eventArgument.ToLower().IndexOf("admin")!=-1)
{
result =eventArgument+ "不能作为用户注册.";
}
else
{
result = eventArgument + "可以注册.";
}
}
#endregion
}