Asp.net回调技术Callback

最新推荐文章于 2025-08-17 17:51:30 发布

最新推荐文章于 2025-08-17 17:51:30 发布 · 130 阅读

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本文介绍了使用ASP.NET实现AJAX回调的三个示例，详细展示了如何通过客户端JavaScript与服务器端C#代码交互，实现异步数据检索及更新。

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.aspx:

<%@ 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="background-color:Pink; width:500px;"></span>
    </div>
    </form>
</body>
</html>

.aspx.cs

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):

<%@ 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="background-color: pink; width: 500;"></span>
    </div>
    </form>
</body>
</html>

.aspx.cs

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:

<%@ 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>

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
}