异步回调方法的使用

来自MSDN:

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
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.Xml.Linq;
using System.Text;

public partial class newSource_callback : System.Web.UI.Page,ICallbackEventHandler
{
    public int cbCount = 0;
    //public string cbcount = "";
    public void RaiseCallbackEvent(String eventArgument)
    {
        cbCount = Convert.ToInt32(eventArgument) + 1;
        //cbcount = eventArgument;
    }
    public string GetCallbackResult()
    {
        return cbCount.ToString();
        //return cbcount;
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        StringBuilder sb = new StringBuilder();
        sb.Append("No page postbacks have occurred.");
        if (Page.IsPostBack)
        {
            sb.Append("A page postback has occurred.");
        }
        MyLabel.Text = sb.ToString();
        ClientScriptManager cs = Page.ClientScript;
        StringBuilder context1 = new StringBuilder();
        context1.Append("function ReceiveServerData1(arg, context){Message1.innerText = arg;value1 = arg;}");
        //context1.Append("{");
        //context1.Append("Message1.innerText = arg;");
        //context1.Append("value1 = arg;");
        //context1.Append("}");
        String cbReference1 = cs.GetCallbackEventReference(this, "arg",
            "ReceiveServerData1", context1.ToString());
        String cbReference2 = cs.GetCallbackEventReference("'" +
            Page.UniqueID + "'", "arg", "ReceiveServerData2", "",
            "ProcessCallBackError", false);
        String callbackScript1 = "function CallTheServer1(arg, context) {" +
            cbReference1 + "; }";
        String callbackScript2 = "function CallTheServer2(arg, context) {" +
            cbReference2 + "; }";
        cs.RegisterClientScriptBlock(this.GetType(), "CallTheServer",
            callbackScript1, true);
        cs.RegisterClientScriptBlock(this.GetType(), "CallTheServer2",
            callbackScript2, true);

    }
}
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="callback.aspx.cs" Inherits="newSource_callback" %>

<!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">
    var value1 = 0;
    var value2 = 0;
    function ReceiveServerData2(arg, context)
    {
        Message2.innerText = arg;
        value2 = arg;
    }
    function ProcessCallBackError(arg, context)
    {
        Message2.innerText = 'An error has occurred.';
    }
</script>

</head>
<body>
    <form id="form1" runat="server">
    <div>
      Callback 1 result: <span id="Message1">0</span>
      <br />
      Callback 2 result: <span id="Message2">0</span>
      <br /> <br />
      <input type="button"
             value="ClientCallBack1"
             onclick="CallTheServer1(value1, alert('Increment value'))"/>   
      <input type="button"
             value="ClientCallBack2"
             onclick="CallTheServer2(value2, alert('Increment value'))"/>
      <br /> <br />
      <asp:Label id="MyLabel"
                 runat="server"></asp:Label>
    </div>

    </form>
</body>
</html>

原文地址:https://www.cnblogs.com/xinzhuangzi/p/4100696.html