(一). 说明
用Tree显示菜单及物品列表(从服务端获取数据)比较方便, 当前显示Tree 主要有两种方式:
1. 在Tree初始化时将数据全部一次性从服务端获取, 获取完数据后页面展开或收缩时就不再需要获取数据,
这样, 获取完数据使用时效率比较高, 但当树节点很多时, 在每次初始化时会有较大的延迟.
2. 初始化时只加载展开的节点, 当用户需要查看某个节点下的数据时, 再去取数据, 这样, 初始化时延迟会相
对减少, 但每次单击节点时要获取数据, 页面每次都要刷新, 所以也会产生延迟.
此事例用Ajax实现第二种方式, 每次只动态加载要展开的节点数据(闭合节点不展开时,则不获取其子节点的
数据), 另外加载节点时页面不会刷新.
(二). 运行示例图
(三). AjaxPro.NET简介
首先对AjaxPro.NET作一下介绍, AjaxPro.NET是一个优秀的Ajax框架, 在实际应用中只要添加其DLL
引用并进行简单的配置, 即可以非常方便的在客户端直接调用服务端方法, 来获取Tree节点.
(四).使用AjaxPro.NET预配置
1. 添加 AjaxPro.dll 文件的引用(示例代码中已经包含,直接COPY过来使用即可).
2. 在Web.config文件中添加以下配置,
1 <httpHandlers>
2 <add verb="POST,GET" path="ajaxpro/*.ashx" type="AjaxPro.AjaxHandlerFactory, AjaxPro" />
3 </httpHandlers>
3. 在要使用AjaxPro.NET框架的页面 *.aspx.cs 的 Page_Load事件中加如下代码:
AjaxPro.Utility.RegisterTypeForAjax(typeof(_Default));
4. 经过以上三步骤后, 只要在后台服务端的方法前面增加属性[AjaxMethod]后:
1 [AjaxMethod()] // or [AjaxPro.AjaxMethod]
2 public ArrayList GetSearchItems( string strQuery )
3 {
4 //生成数据源
5 ArrayList items = new ArrayList();
6 items.Add("King");
7 items.Add("Rose");
8 return items ;
9 }
10
就可以在客户端直接使用服务端方法, 非常方便, 客户端调用后台代码如下:
(五). 代码
1. 页面 Tree.aspx 代码:
1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Tree.aspx.cs" Inherits="_Default" %>
2
3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
4
5 <html xmlns="http://www.w3.org/1999/xhtml" >
6 <head runat="server">
7 <title>Ajax Efficient Tree</title>
8 <link type="text/css" href="css/tree.css" rel="stylesheet">
9 </head>
10 <body>
11 <form id="form1" runat="server">
12 <div>
13 <asp:Panel ID="Panel1" runat="server" Height="424px" Width="251px">
14 <div id="CategoryTree" class="TreeMenu"></div>
15 </asp:Panel>
16 <script language="jscript">
17 var tree = document.getElementById("CategoryTree");
18 var root = document.createElement("li");
19 root.id = "li_0";
20 tree.appendChild( root );
21 ExpandSubCategory( 0 );
22 function ExpandSubCategory( categoryID )
23 {
24 var liFather = document.getElementById( "li_" + categoryID );
25 if( liFather.getElementsByTagName("li").length > 0)
26 {
27 ChangeStatus( categoryID );
28 return;
29 }
30 liFather.className = "Opened";
31 SwitchNode( categoryID, true );
32
33 //仅获取当前节点的子Nodes
34 _Default.GetSubCategory( categoryID, GetSubCategory_callback );
35 }
36 function SwitchNode( CategoryID, show )
37 {
38 var li_father = document.getElementById("li_" + CategoryID);
39 if( show )
40 {
41 var ul = document.createElement("ul");
42 ul.id = "ul_note_" + CategoryID;
43
44 var note = document.createElement("li");
45 note.className = "Child";
46
47 var img = document.createElement("img");
48 img.className = "s";
49 img.src = "css/s.gif";
50
51 var a = document.createElement("a");
52 a.href = "javascript:void(0);";
53 a.innerHTML = "Please waiting
54
55 note.appendChild(img);
56 note.appendChild(a);
57 ul.appendChild(note);
58 li_father.appendChild(ul);
59 }
60 else
61 {
62 var ul = document.getElementById("ul_note_" + CategoryID );
63 if( ul )
64 {
65 li_father.removeChild(ul);
66 }
67 }
68 }
69 function GetSubCategory_callback( response )
70 {
71 var dt = response.value.Tables[0];
72 if( dt.Rows.length > 0 )
73 {
74 var iCategoryID = dt.Rows[0].FatherID;
75 }
76 var li_father = document.getElementById("li_" + iCategoryID );
77 var ul = document.createElement("ul");
78 for( var i = 0; i < dt.Rows.length; i++ )
79 {
80 if( dt.Rows[i].IsChild == 1 )
81 {
82 var li = document.createElement("li");
83 li.className = "Child";
84 li.id = "li_" + dt.Rows[i].CategoryID;
85 var img = document.createElement("img");
86 img.id = dt.Rows[i].CategoryID;
87 img.className = "s";
88 img.src = "css/s.gif";
89 var a = document.createElement("a");
90 a.href = "javascript:OpenDocument('" + dt.Rows[i].CategoryID + "');";
91 a.innerHTML = dt.Rows[i].CategoryName;
92 }
93 else
94 {
95 var li = document.createElement("li");
96 li.className = "Closed";
97 li.id = "li_" + dt.Rows[i].CategoryID;
98 var img = document.createElement("img");
99 img.id = dt.Rows[i].CategoryID;
100 img.className = "s";
101 img.src = "css/s.gif";
102 img.onclick = function(){ ExpandSubCategory( this.id ); };
103 img.alt = "Expand/collapse";
104 var a = document.createElement("a");
105 a.href = "javascript:ExpandSubCategory('" + dt.Rows[i].CategoryID + "');";
106 a.innerHTML = dt.Rows[i].CategoryName;
107 }
108 li.appendChild(img);
109 li.appendChild(a);
110 ul.appendChild(li);
111 }
112 li_father.appendChild(ul);
113 SwitchNode( iCategoryID, false );
114 }
115
116 //单击叶节点时, 异步从服务端获取单个节点的数据.
117 function OpenDocument( CategoryID )
118 {
119 _Default.GetNameByCategoryID( CategoryID, GetNameByCategoryID_callback );
120 }
121
122 function GetNameByCategoryID_callback( response )
123 {
124 alert( response.value );
125 }
126
127 function ChangeStatus( CategoryID )
128 {
129 var li_father = document.getElementById("li_" + CategoryID );
130 if( li_father.className == "Closed" )
131 {
132 li_father.className = "Opened";
133 }
134 else
135 {
136 li_father.className = "Closed";
137 }
138 }
139 </script>
140 </div>
141 </form>
142 </body>
143 </html>
2. 页面后台文件 Tree.aspx.cs 代码:
1 using System;
2 using System.Data;
3 using System.Configuration;
4 using System.Web;
5 using System.Web.Security;
6 using System.Web.UI;
7 using System.Web.UI.WebControls;
8 using System.Web.UI.WebControls.WebParts;
9 using System.Web.UI.HtmlControls;
10
11 public partial class _Default : System.Web.UI.Page
12 {
13 //此对象用于存放所有的节点数
14 public static DataSet dsAllNodes = new DataSet();
15
16 protected void Page_Load(object sender, EventArgs e)
17 {
18 AjaxPro.Utility.RegisterTypeForAjax(typeof(_Default));
19 CreateNodes();
20 }
21
22 private DataTable CreateStructure()
23 {
24 DataTable dt = new DataTable();
25 dt.Columns.Add(new DataColumn("CategoryID", typeof(int)));
26 dt.Columns.Add(new DataColumn("CategoryName", typeof(string)));
27 dt.Columns.Add(new DataColumn("FatherID", typeof(string)));
28 dt.Columns.Add(new DataColumn("IsChild", typeof(bool)));
29 return dt;
30 }
31 public void CreateNodes()
32 {
33 DataTable dt = this.CreateStructure();
34
35 DataRow drNew = dt.NewRow();
36 drNew["CategoryID"] = 1;
37 drNew["CategoryName"] = "物品类别";
38 drNew["FatherID"] = 0;
39 dt.Rows.Add( drNew );
40
41 drNew = dt.NewRow();
42 drNew["CategoryID"] = 2;
43 drNew["CategoryName"] = "水果";
44 drNew["FatherID"] = 1;
45 dt.Rows.Add( drNew );
46
47 drNew = dt.NewRow();
48 drNew["CategoryID"] = 3;
49 drNew["CategoryName"] = "工具";
50 drNew["FatherID"] = 1;
51 dt.Rows.Add( drNew );
52
53 drNew = dt.NewRow();
54 drNew["CategoryID"] = 4;
55 drNew["CategoryName"] = "萍果";
56 drNew["FatherID"] = 2;
57 dt.Rows.Add( drNew );
58
59 drNew = dt.NewRow();
60 drNew["CategoryID"] = 5;
61 drNew["CategoryName"] = "香蕉";
62 drNew["FatherID"] = 2;
63 dt.Rows.Add( drNew );
64
65 drNew = dt.NewRow();
66 drNew["CategoryID"] = 6;
67 drNew["CategoryName"] = "桔子";
68 drNew["FatherID"] = 2;
69 dt.Rows.Add( drNew );
70
71 drNew = dt.NewRow();
72 drNew["CategoryID"] = 7;
73 drNew["CategoryName"] = "萝卜";
74 drNew["FatherID"] = 2;
75 dt.Rows.Add( drNew );
76
77 drNew = dt.NewRow();
78 drNew["CategoryID"] = 8;
79 drNew["CategoryName"] = "钢笔";
80 drNew["FatherID"] = 3;
81 dt.Rows.Add( drNew );
82
83 drNew = dt.NewRow();
84 drNew["CategoryID"] = 9;
85 drNew["CategoryName"] = "铅笔";
86 drNew["FatherID"] = 3;
87 dt.Rows.Add( drNew );
88
89 drNew = dt.NewRow();
90 drNew["CategoryID"] = 10;
91 drNew["CategoryName"] = "尺子";
92 drNew["FatherID"] = 3;
93 dt.Rows.Add( drNew );
94
95 drNew = dt.NewRow();
96 drNew["CategoryID"] = 11;
97 drNew["CategoryName"] = "橡皮";
98 drNew["FatherID"] = 3;
99 dt.Rows.Add( drNew );
100
101 dsAllNodes.Tables.Add(dt);
102 }
103
104 [AjaxPro.AjaxMethod]
105 public DataSet GetSubCategory(int CategoryID)
106 {
107 DataSet ds = new DataSet();
108 DataTable dt = this.CreateStructure();
109 DataRow[] drSelect = dsAllNodes.Tables[0].Select("FatherID=" + CategoryID.ToString());
110 foreach (DataRow drTemp in drSelect)
111 {
112 DataRow dr = dt.NewRow();
113 dr["CategoryID"] = drTemp["CategoryID"];
114 dr["CategoryName"] = drTemp["CategoryName"];
115 dr["FatherID"] = drTemp["FatherID"];
116 dr["IsChild"] = IsLeaf( int.Parse( drTemp["CategoryID"].ToString() ) );
117 dt.Rows.Add(dr);
118 }
119 ds.Tables.Add(dt);
120 return ds;
121 }
122
123 [AjaxPro.AjaxMethod]
124 public bool IsLeaf(int Category)
125 {
126 foreach(DataRow dr in dsAllNodes.Tables[0].Rows)
127 {
128 if (dr["FatherID"] != null && int.Parse(dr["FatherID"].ToString()) == Category)
129 {
130 return false;
131 }
132 }
133 return true;
134 }
135
136 [AjaxPro.AjaxMethod]
137 public string GetNameByCategoryID(string CategoryID )
138 {
139 foreach( DataRow dr in dsAllNodes.Tables[0].Rows )
140 {
141 if( dr["CategoryID"].ToString() == CategoryID.ToString() )
142 {
143 return dr["CategoryName"].ToString();
144 }
145 }
146 return "";
147 }
148 }
(六). 示例代码下载:
http://www.cnitblog.com/Files/ChengKing/AjaxPro.net_EfficientTree.rar
