Ajax实现无刷新树

1.建立一个aspx页面
html代码

< html  xmlns ="http://www.w3.org/1999/xhtml"   >
< head  id ="Head1"  runat ="server" >
     < title > 小山 </ title >
     < link  type ="text/css"  href ="../../Styles/tree_css/tree.css"  rel ="stylesheet" >
</ head >
< body >
     < form  id ="Form1"  runat ="server" >
     < table  width =100%  cellpadding =0  cellspacing =0  border =0 >
         < colgroup >
             < col  width =180  />
             < col  />
         </ colgroup >
         < tr >
             < td >
                 < div  class ="TreeMenu"  id ="CategoryTree"  style ="width: 100%; height: 489px" >
                 </ div >
             </ td >
             < td >
                 < iframe  id =furl  height =20  style ="height: 497px; width: 100%;" ></ iframe >
             </ td >
         </ tr >
     </ table >     
                            
             < script  language ="jscript" >
            function el(id)
            {
                return document.getElementById(id);                
            }
            function ExpandSubCategory(iCategoryID)
            {
                var li_father = el("li_" + iCategoryID);
                if (li_father.getElementsByTagName("li").length > 0) //分类已下载
                {
                    ChangeStatus(iCategoryID);
                    return;
                }
                
                li_father.className = "Opened";
                
                switchNote(iCategoryID, true);
                AjaxMethod.GetSubCategory(iCategoryID, GetSubCategory_callback);                
            }

            function GetSubCategory_callback(response)
            {
                var dt = response.value.Tables[0];
                if (dt.Rows.length > 0)
                {
                    var iCategoryID = dt.Rows[0].FatherID;
                }
                var li_father = el("li_" + iCategoryID);
                var ul = document.createElement("ul");
                for (var i = 0;i < dt.Rows.length;i++)
                {
                    if (dt.Rows[i].IsChild == 1) //叶子节点
                    {
                        var li = document.createElement("li");
                        li.className = "Child";
                        li.id = "li_" + dt.Rows[i].CategoryID;
                        
                        var img = document.createElement("img");
                        img.id = dt.Rows[i].CategoryID;
                        img.className = "s";
                        img.src = "../../Styles/tree_css/s.gif";
                        
                        var a = document.createElement("a");
                        var id = dt.Rows[i].CategoryID;
                        a.onmouseover = function()
                        {
                            PreviewImage(id);
                        };
                        a.href = "javascript:OpenDocument('" + dt.Rows[i].CategoryID + "');";
                        a.innerHTML = dt.Rows[i].CategoryName;
                    }
                    else
                    {
                        var li = document.createElement("li");
                        li.className = "Closed";
                        li.id = "li_" + dt.Rows[i].CategoryID;
                        
                        var img = document.createElement("img");
                        img.id = dt.Rows[i].CategoryID;
                        img.className = "s";
                        img.src = "../../Styles/tree_css/s.gif";
                        img.onclick = function () {
                            ExpandSubCategory(this.id);
                        };
                        img.alt = "展开/折叠";
                        
                        var a = document.createElement("a");
                        a.href = "javascript:ExpandSubCategory(" +
                            dt.Rows[i].CategoryID + ");";
                        a.innerHTML = dt.Rows[i].CategoryName;
                    }
                    li.appendChild(img);
                    li.appendChild(a);
                    ul.appendChild(li);    
                }
                li_father.appendChild(ul);
                
                switchNote(iCategoryID, false);
            }
            
            // 叶子节点的单击响应函数
            function OpenDocument(iCategoryID)
            {
                // 预加载信息
                PreloadFormUrl(iCategoryID);
            }
            
            function PreviewImage(iCategoryID)
            {
                
            }

            function ChangeStatus(iCategoryID)
            {
                var li_father = el("li_" + iCategoryID);
                if (li_father.className == "Closed")
                {
                    li_father.className = "Opened";
                }
                else
                {
                    li_father.className = "Closed";
                }                
            }

            function switchNote(iCategoryID, show)
            {
                var li_father = el("li_" + iCategoryID);
                if (show)
                {
                    var ul = document.createElement("ul");
                    ul.id = "ul_note_" + iCategoryID;
                    
                    var note = document.createElement("li");
                    note.className = "Child";
                    
                    var img = document.createElement("img");
                    img.className = "s";
                    img.src = "../../Styles/tree_css/s.gif";
                    
                    var a = document.createElement("a");
                    a.href = "javascript:void(0);";
                    a.innerHTML = "请稍候";
                    
                    note.appendChild(img);
                    note.appendChild(a);
                    ul.appendChild(note);
                    li_father.appendChild(ul);
                }
                else
                {
                    var ul = el("ul_note_" + iCategoryID);
                    if (ul)
                    {
                        li_father.removeChild(ul);
                    }                
                }
            }

            // 加载根节点
            var tree = el("CategoryTree");
            var root = document.createElement("li");
            root.id = "li_0";
            tree.appendChild(root);
            
            // 加载页面时显示第一级分类
            ExpandSubCategory(0);
            
            function PreloadFormUrl(iCategoryID)
            {
                // 采用同步调用的方式获取图片的信息                
                var ds = AjaxMethod.GetFormsList(iCategoryID).value;
                // 如果返回了结果
                if (ds)
                {
                    // 判断数据表是否不为空
                    if (ds.Tables[0].Rows.length > 0)
                    {
                        // 返回的信息数据表
                        dt = ds.Tables[0];
                        el("furl").src = dt.Rows[0].FormUrl;                                    
                    }
                    else // 分类下没有
                    {                        
                    }
                }                
            }
             </ script >             
     </ form >
</ body >
</ html >

2.cs代码

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;
using  AjaxPro;

public  partial  class  Pages_Home_HomePage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Utility.RegisterTypeForAjax(typeof(AjaxMethod));
    }
}

3.建立一个tree.css的css样式

a
{} {
    text-decoration:none;
}
a,a:visited
{} {
    color:#000;
    background:inherit;
}
body
{} {
    margin:0;
    padding:20px;
    font:12px tahoma,宋体,sans-serif;
}
dt
{} {
    font-size:22px;
    font-weight:bold;
    margin:0 0 0 15px;
}
dd
{} {
    margin:0 0 0 15px;
}
h4
{} {
    margin:0;
    padding:0;
    font-size:18px;
    text-align:center;
}
p
{} {
    margin:0;
    padding:0 0 0 18px;
}
p a,p a:visited
{} {
    color:#00f;
    background:inherit;
}

.TreeMenu img.s
{} {
    cursor:hand;
    vertical-align:middle;
}
.TreeMenu ul
{} {
    padding:0;
}
.TreeMenu li
{} {
    list-style:none;
    padding:0;
}
.Closed ul
{} {
    display:none;
}
.Child img.s
{} {
    background:none;
    cursor:default;
}

#CategoryTree ul
{} {
    margin:0 0 0 17px;
}
#CategoryTree img.s
{} {
    width:34px;
    height:18px;
}
#CategoryTree .Opened img.s
{} {
    background:url(skin3/opened.gif) no-repeat 0 1px;
}
#CategoryTree .Closed img.s
{} {
    background:url(skin3/closed.gif) no-repeat 0 1px;
}
#CategoryTree .Child img.s
{} {
    background:url(skin3/child.gif) no-repeat 13px 2px;
}

#CategoryTree
{} {
    float:left;
    width:249px;
    border:1px solid #99BEEF;
    background:#D2E4FC;
    color:inherit;
    margin:3px;
    padding:3px;
    height:600px;
}

4.建立一个类AjaxMethod

using  System;
using  System.Data;
using  System.Data.SqlClient;
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;
using  AjaxPro;

/**/ /// <summary>
/// Summary description for AjaxMethod
/// </summary>
public   class  AjaxMethod
{} {
    public AjaxMethod()
    {
        //
        // TODO: Add constructor logic here
        //
    }
    [AjaxMethod(HttpSessionStateRequirement.ReadWrite)]
    public static DataSet GetSubCategory(int iCategoryID)
    {}{
        string sql = string.Format("SELECT CategoryID, CategoryName, FatherID, dbo.IsLeaf(CategoryID) as IsChild FROM Category WHERE FatherID = {0}", iCategoryID);
        return GetDataSet(sql);
    }

    [AjaxMethod(HttpSessionStateRequirement.ReadWrite)]
    public static DataSet GetFormsList(int iCategoryID)
    {}{
        string sql = string.Format("SELECT * FROM forms WHERE form_category_id = {0}", iCategoryID);
        return GetDataSet(sql);
    }
public static string ConnectionString = ConfigurationSettings.AppSettings["ConnectionString"].ToString();

        public static DataSet GetDataSet(string sql)
        {}{
            SqlDataAdapter sda = new SqlDataAdapter(sql, ConnectionString);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            if (ds != null)
                return ds;
            else
                return null;
        }
}

5.sql脚本

if   exists  ( select   *   from  dbo.sysobjects  where  id  =   object_id (N ' [dbo].[Category] ' )  and   OBJECTPROPERTY (id, N ' IsUserTable ' )  =   1 )
drop   table   [ dbo ] . [ Category ]
GO

if   exists  ( select   *   from  dbo.sysobjects  where  id  =   object_id (N ' [dbo].[Forms] ' )  and   OBJECTPROPERTY (id, N ' IsUserTable ' )  =   1 )
drop   table   [ dbo ] . [ Forms ]
GO

CREATE   TABLE   [ dbo ] . [ Category ]  (
     [ CategoryID ]   [ int ]   IDENTITY  ( 1 ,  1 )  NOT   NULL  ,
     [ CategoryName ]   [ varchar ]  ( 20 ) COLLATE Chinese_PRC_CI_AS  NULL  ,
     [ FatherID ]   [ int ]   NULL  
)  ON   [ PRIMARY ]
GO

CREATE   TABLE   [ dbo ] . [ Forms ]  (
     [ FormID ]   [ int ]   IDENTITY  ( 1 ,  1 )  NOT   NULL  ,
     [ FormName ]   [ nvarchar ]  ( 50 ) COLLATE Chinese_PRC_CI_AS  NULL  ,
     [ FormUrl ]   [ nvarchar ]  ( 50 ) COLLATE Chinese_PRC_CI_AS  NULL  ,
     [ Form_category_id ]   [ int ]   NULL  ,
     [ target ]   [ char ]  ( 10 ) COLLATE Chinese_PRC_CI_AS  NULL  
)  ON   [ PRIMARY ]
GO
CREATE   FUNCTION  IsLeaf ( @cat_id   int )  
RETURNS   int   AS   
BEGIN  

declare   @count   int
select   @count   =  ( select   count ( * )  from  Category  where  FatherID = @cat_id ) 
if  ( @count = 0 )
return   1
return   0

END