客户端回调实现 (C#) 示例

来源：互联网发布：talktothemoon知乎编辑：程序博客网时间：2024/04/27 21:34
<%@ Page Language="C#" AutoEventWireup="true" 
  CodeFile="ClientCallback.aspx.cs" Inherits="ClientCallback" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 
  1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html  >
<head id="Head1" runat="server">
  <title>Client Callback Example</title>
  <script type="text/ecmascript">
    function LookUpStock()
    {
        var lb = document.getElementById("ListBox1");
        var product = lb.options[lb.selectedIndex].text;
        CallServer(product, "");
    }
    function ReceiveServerData(rValue)
    {   
        document.getElementById("ResultsSpan").innerHTML = rValue;
    }
  </script>
</head>
<body>
  <form id="form1" runat="server">
    <div>
      <asp:ListBox ID="ListBox1" Runat="server"></asp:ListBox>
      <br />
      <br />
      <button type="Button" onclick="LookUpStock()">Look Up Stock</button>
      <br />
      <br />
      Items in stock: <span id="ResultsSpan" runat="server"></span>
      <br />
    </div>
  </form>
</body>
</html>
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;
public partial class ClientCallback : System.Web.UI.Page,
     System.Web.UI.ICallbackEventHandler
{
    protected System.Collections.Specialized.ListDictionary catalog;
    protected String returnValue;
    protected void Page_Load(object sender, EventArgs e)
    {
        String cbReference =
            Page.ClientScript.GetCallbackEventReference(this,
            "arg", "ReceiveServerData", "context");
        String callbackScript;
        callbackScript = "function CallServer(arg, context)" +
            "{ " + cbReference + ";}";
        Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
            "CallServer", callbackScript, true);
        catalog = new System.Collections.Specialized.ListDictionary();
        catalog.Add("monitor", 12);
        catalog.Add("laptop", 10);
        catalog.Add("keyboard", 23);
        catalog.Add("mouse", 17);
        ListBox1.DataSource = catalog;
        ListBox1.DataTextField = "key";
        ListBox1.DataBind();
    }
    public void RaiseCallbackEvent(String eventArgument)
    {
        if (catalog[eventArgument] == null)
        {
            returnValue = "-1";
        }
        else
        {
            returnValue = catalog[eventArgument].ToString();
        }
    }
    public String GetCallbackResult()
    {
        return returnValue;
    }
}