基于ICallbackEventHandler的大数据量树

本文主要在asp.net下面制作生成,利用到了JQuery中的Tree控件,采用的是asp.net中ICallbackEventHandler接口实现.

本方法比较简单,可以很方便的对一些逻辑要求不高的功能使用.具体生成页面如下:

然后就是本页面所用到的代码:

首先是前台页面

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <script src="jquery.treeview/lib/jquery.js" type="text/javascript"></script>
    <script src="jquery.treeview/common.js" type="text/javascript"></script>
    <script src="jquery.treeview/jquery.tree.js" type="text/javascript"></script>
    <link href="jquery.treeview/tree.css" rel="stylesheet" type="text/css" />
    <title>基于ICallbackEventHandler的轻量级ajax回调方法</title>
    <script type="text/javascript">
        $(document).ready(function() {
            raiseEvent();
        });
        
        function rServer(arg, context) {
              var o = { showcheck: true };   //显示按钮
              o.data = eval(arg);        //处理json数据
              $("#showTree").treeview(o);  //绑定到树上
        }

        function raiseEvent(arg, context) {
            <%=ClientScript.GetCallbackEventReference(this,"arg","rServer","context") %>;  
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div id="showTree">
    </div>
    </form>
</body>
</html>

需要说明的是raiseEvent方法和rServer方法,首先是raiseEvent方法发起对服务器端的ajax请求,请求的数据内容存在于arg参数中,然后传递到后台,而其中的代码

<%=ClientScript.GetCallbackEventReference(this,"arg","rServer","context") %>;
则是指明了rServer是回调成功后,所调用的方法.

后台代码如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

/*******************************************************
 * 基于ICallbackEventHandler的轻量级ajax回调方法
 * 使用方式:首先页面需要继承自ICallbackEventHandler接口
 * 然后页面必须实现RaiseCallbackEvent和GetCallbackResult
 * 方法,其中注意的是,前面一个函数先被调用,用来接收从前台
 * 传送来的数据,后面一个函数是将处理过的函数返回到前台
 * ****************************************************/

public partial class _Default : System.Web.UI.Page,ICallbackEventHandler   
{
    protected void Page_Load(object sender, EventArgs e)
    {
        
    }

    public string jsonStr = string.Empty;

    public  string GetJson()
    {
        string json = "[";
        IList<Tree> t = DB.returnParentTree();
        foreach (Tree model in t)
        {
            if (model != t[t.Count - 1])
            {
                json += GetJsonByModel(model) + ",";
            }
            else
            {
                json += GetJsonByModel(model);
            }
        }
        json += "]";
        json = json.Replace("'", "\"");
        return json;
    }

    public  string GetJsonByModel(Tree t)
    {
        string json = "";
        bool flag = DB.isHaveChild(t.ModuleID);

        json = "{"
                  + "'id':'" + t.ModuleID + "',"
                  + "'text':'" + t.ModuleName + "',"
                  + "'value':'" + t.ModuleID + "',"
                  + "'showcheck':true,"
                  + "'checkstate':'0',"
                  + "'hasChildren':" + flag.ToString().ToLower() + ","
                  + "'isexpand':false,"
                  + "'ChildNodes':"; 
        if (!flag)
        {
            json += "null,";
            json += "'complete':false}";
        }
        else
        {
            json += "[";
            IList<Tree> list = DB.getChild(t.ModuleID);
            foreach (Tree tree in list)
            {
                if (tree != list[list.Count - 1])
                {
                    json += GetJsonByModel(tree) + ",";
                }
                else
                {
                    json += GetJsonByModel(tree);
                }
            }
            json += "],'complete':true}";
        }
        return json;
    }

    public string GetCallbackResult()
    {
        return jsonStr;
    }

    public void RaiseCallbackEvent(string eventArgument)
    {
        jsonStr = GetJson();
    }
}