非Ajax实现客户端的异步调用

先来看 default.aspx页面：

<%@ 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 language="javascript" type="text/javascript">
    function GetNumber()
    {
       UseCallback();
    }

    function GetRandomNumberFromServer(values,content)
    {
       document.getElementById("TextBox1").value=values;
    }
  </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <input id="Button1" type="button" value="button" onclick="GetNumber()" /></div>
    </form>
</body>
</html>

接下来看deault.cs页面代码：

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;

public partial class _Default : System.Web.UI.Page,System.Web.UI.ICallbackEventHandler
{
    private string a = null;
    protected void Page_Load(object sender, EventArgs e)
    {
        string cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "GetRandomNumberFromServer", "context");
        string cbScript = "function UseCallback(arg,context)" + "{" + cbReference + ";" + "}";
        Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "UseCallback", cbScript, true);
    }

    public string GetCallbackResult()
    {
        return a;
    }

    public void RaiseCallbackEvent(string enentArg)
    {
        Random rd = new Random();
        a = rd.Next().ToString();
    }
}

哈哈，就这么简单，点击标准html按钮就会自动获取后台自动生成的一个随机数，并显示到页面上，哈哈，是不是很强大～！！！