浅析jQuery EasyUI中的tree使用指南

本文记录的是带领成员开发一个小模块功能的时候，需要用到弹出窗口加载树状级联单位选择，最后决定用采用jQuery+EasyUI插件进行开发。但是在使用EasyUI中tree的插件时，碰到了不少麻烦。为了提供弹出树的显示速度，就采用异步加载数节点值，首先先加载根节点，然后根据点击的节点展开加载子节点。

往往结果和预期的都不一样，困惑了几天，展开后子节点是动态加载了，但是收缩后无法清空之前填充的数据；第二次在展开时，子节点又被重复加载了一遍，造成了数据重复显示，并没有提供清除子节点的方法。想尽了各种办法来解决这个问题，只能换另一种形式加载子节点的值了，把每一个节点值保存起来，判断是否已经存在，存在就不在去加载。

两种方法见实例：

var treeTitle = '选择列表';

var treeUrl = '../DataAshx/getTreeNode.ashx?pid=-1';

var nodeExp=false;

var nodekeep="";

var rows;

var noinf=0;

$(function() {

    $('#treewindow').window({

        title: treeTitle,

        width: 400,

        height: 400,

        modal: true,

        shadow: false,

        closed: true,

        resizable: false,

        maximizable: false,

        minimizable: false,

        collapsible: false

    });

});

function treeWindowOpen(name,rowIndx) {

    $('#treewindow').window('open');

    nodekeep="";

    nodeExp=false;

    rows=rowIndx.toString();

    $('#basetree').tree({

        checkbox: true,

        animate: true,

        url: treeUrl+"&coln="+escape(name.toString()),

        cascadeCheck: true,

        onlyLeafCheck: false,

        onBeforeExpand: function(node, param) {

//------------第一种方法：异步加载子节点值-------------

//            $('#basetree').tree('options').url = "../DataAshx/getTreeNode.ashx?pid=" + node.id+"&coln="+escape(name.toString());

//------------第二种方法：Ajax方法返回子节点Json值，使用append方法加载子节点       

        $.ajax({

                type: "POST",

                url: "../DataAshx/getTreeNode.ashx?pid=" + node.id+"&coln="+escape(name.toString())+"&casn="+escape(node.attributes.cas.toString()),

                cache: false,

                async: false,

                dataType: "json",

                success: function(data) {

                    if(nodekeep.indexOf(node.id)==-1)

                    {

                     append(data, node);

                     nodeExp = true;

                    }

                }

            });

            $("#radCollapse").removeAttr("checked");

        },

        onLoadError:function(Error)

        {

            $.messager.alert('提示', '查询语句出错', 'error');

            if(nodeExp==false)

            {

                $("#basetree").children().remove();

            }

        },

        onLoadSuccess:function(success)

        {

            var child=$("#basetree").children().length;

            noinf++;

            if(child==0&&noinf>1)

            {

                $.messager.alert('提示', '数据不存在', 'Info');

            }

        }

    });

}

function treeWindowClose() {

    $('#treewindow').window('close');

    nodekeep="";

    nodekeep=false;

}

function treeWindowSubmit() {

    var nodes = $('#basetree').tree('getChecked');

    var info = '';

    if (nodes.length > 0) {

        for (var i = 0; i < nodes.length; i++) {

            if (info != '') { info += ','; }

            info += nodes[i].text;

        }

        //alert(JSON.stringify(nodes));

    }

    else {

        var node = $('#basetree').tree('getSelected');

        if (node != null) {

            info = node.text;                

        }

    }

    $("#"+rows).val(info);

    $('#treewindow').window('close');

    nodekeep="";

    nodeExp=false;

}

//全部展开

function collapseAll() {

    $("#radCollapse").attr("checked", "checked");

    var node = $('#basetree').tree('getSelected');

    if (node) {

        $('#basetree').tree('collapseAll', node.target);

    } else {

        $('#basetree').tree('collapseAll');

    }

}

//全部收缩

function expandAll() {

    var node = $('#basetree').tree('getSelected');

    if (node) {

        $('#basetree').tree('expandAll', node.target);

    } else {

        $('#basetree').tree('expandAll');

    }

}

//增加子节点

function append(datas,cnode) {

    var node = cnode;

    $('#basetree').tree('append', {

        parent: node.target,

        data: datas

    });

    nodekeep+=","+node.id;

}

//重新加载

function reload() {

    var node = $('#basetree').tree('getSelected');

    if (node) {

        $('#basetree').tree('reload', node.target);

    } else {

        $('#basetree').tree('reload');

    }

}

//删除子节点

function remove() {

    var node = $('#basetree').tree('getSelected');

    $('#basetree').tree('remove',node.target);

}

页面getTreeNode.ashx返回树节点JSON格式数据：

<%@ WebHandler Language="C#" Class="getTreeNode" %>

using System;

using System.Collections;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Services;

using System.Web.Services.Protocols;

using System.Xml.Linq;

using System.Collections.Generic;
public class getTreeNode : IHttpHandler, System.Web.SessionState.IRequiresSessionState

{

    public void ProcessRequest(HttpContext context)

    {

        context.Response.ContentType = "text/plain";

        DataTable dt = (DataTable)context.Session["viewmaintain"];

        string parentId = string.Empty;

        string resultStr = string.Empty;

        string attributes = string.Empty;

        string colName = string.Empty;

        string sql = string.Empty;

        string Casname = string.Empty;

        bool colt = false;

        string icon = "icon-profile";

        if (!string.IsNullOrEmpty(context.Request.QueryString["pid"]))

        {

            parentId = context.Request.QueryString["pid"].ToString();

        }

        if ((!string.IsNullOrEmpty(context.Request.QueryString["coln"])) && (string.IsNullOrEmpty(context.Request.QueryString["casn"])))

        {

            colName = HttpUtility.UrlDecode(context.Request.QueryString["coln"].ToString()); 

            if (dt != null)

            {

                bool pt = true;

                while (pt)

                {

                    for (int i = 0; i < dt.Rows.Count; i++)

                    {

                        Casname = dt.Rows[i]["view_colname"].ToString();

                        if (dt.Rows[i]["view_colname"].ToString() == colName)

                        {

                            if (dt.Rows[i]["view_cas"].ToString() != null&&dt.Rows[i]["view_cas"].ToString() !="")

                            {

                                colName = dt.Rows[i]["view_cas"].ToString();

                            }

                            else

                            {

                                colt = true;

                                sql = dt.Rows[i]["view_sql"].ToString();

                                pt = false;

                            }

                            break;

                        }

                    }

                }

            }

        }

        if ((!string.IsNullOrEmpty(context.Request.QueryString["casn"])) && (!string.IsNullOrEmpty(context.Request.QueryString["coln"])))

        {

           string casnName = HttpUtility.UrlDecode(context.Request.QueryString["casn"].ToString());

           colName = HttpUtility.UrlDecode(context.Request.QueryString["coln"].ToString()); 

            if (dt != null)

            {

                for (int i = 0; i < dt.Rows.Count; i++)

                {

                    Casname = dt.Rows[i]["view_colname"].ToString();

                    if (dt.Rows[i]["view_cas"].ToString() == casnName && casnName != colName)

                    {

                        colt = true;

                        sql = dt.Rows[i]["view_sql"].ToString();

                        break;

                    }

                }

            }

        }

        try

        {

            if (parentId != "" && colt == true)

            {

                //此处省略得到数据列表的代码

                List<TreeInfo> ltree = DAL_TreeInfo.GetItemValue(parentId, sql);

                resultStr = "";

                resultStr += "[";

                if (ltree.Count > 0)

                {

                    foreach (TreeInfo item in ltree)

                    {

                        attributes = "";

                        attributes += "{\"cas\":\"" + Casname;

                        attributes += "\",\"val\":\"" + item._text + "\"}";

                        resultStr += "{";

                        resultStr += string.Format("\"id\": \"{0}\", \"text\": \"{1}\", \"iconCls\": \"{2}\", \"attributes\": {3}, \"state\": \"closed\"", item._id, item._text, icon, attributes);

                        resultStr += "},";

                    }

                    resultStr = resultStr.Substring(0, resultStr.Length - 1);

                }

                resultStr += "]";

            }

            else

            {

                resultStr = "[]";

            }

        }

        catch (Exception ex)

        {

            resultStr = "出错";

        }

        context.Response.Write(resultStr);

    }

    public bool IsReusable

    {

        get

        {

            return false;

        }

    }

}

 

关键性的代码都已经在上面了，目前也就只能想到这种办法来解决了，有时间的话可以给tree扩展一下，添加一个清除子节点的方法，这样应该实现起来会更容易方便。

小弟在此献丑了，不知道各位专家、同仁有没有遇到类似的问题，或者有其它更好的解决办法，欢迎在这交流。