淺析jQuery EasyUI中的tree使用指南

2019-11-20 13:40:02

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　　本文記錄的是帶領成員開發一個小模塊功能的時候，需要用到彈出窗口加載樹狀級聯單位選擇，最后決定用采用jQuery+EasyUI插件進行開發。但是在使用EasyUI中tree的插件時，碰到了不少麻煩。為了提供彈出樹的顯示速度，就采用異步加載數節點值，首先先加載根節點，然后根據點擊的節點展開加載子節點。

　　往往結果和預期的都不一樣，困惑了幾天，展開后子節點是動態加載了，但是收縮后無法清空之前填充的數據；第二次在展開時，子節點又被重復加載了一遍，造成了數據重復顯示，并沒有提供清除子節點的方法。想盡了各種辦法來解決這個問題，只能換另一種形式加載子節點的值了，把每一個節點值保存起來，判斷是否已經存在，存在就不在去加載。

　　兩種方法見實例：

復制代碼代碼如下:

var treeTitle = '選擇列表';
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) {
//------------第一種方法：異步加載子節點值-------------
//            $('#basetree').tree('options').url = "../DataAshx/getTreeNode.ashx?pid=" + node.id+"&coln="+escape(name.toString());
//------------第二種方法：Ajax方法返回子節點Json值，使用append方法加載子節點       
        $.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', '查詢語句出錯', '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', '數據不存在', '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;
}
//全部展開
function collapseAll() {
    $("#radCollapse").attr("checked", "checked");
    var node = $('#basetree').tree('getSelected');
    if (node) {
        $('#basetree').tree('collapseAll', node.target);
    } else {
        $('#basetree').tree('collapseAll');
    }
}
//全部收縮
function expandAll() {
    var node = $('#basetree').tree('getSelected');
    if (node) {
        $('#basetree').tree('expandAll', node.target);
    } else {
        $('#basetree').tree('expandAll');
    }
}
//增加子節點
function append(datas,cnode) {
    var node = cnode;
    $('#basetree').tree('append', {
        parent: node.target,
        data: datas
    });
    nodekeep+=","+node.id;
}
//重新加載
function reload() {
    var node = $('#basetree').tree('getSelected');
    if (node) {
        $('#basetree').tree('reload', node.target);
    } else {
        $('#basetree').tree('reload');
    }
}
//刪除子節點
function remove() {
    var node = $('#basetree').tree('getSelected');
    $('#basetree').tree('remove',node.target);
}

　　頁面getTreeNode.ashx返回樹節點JSON格式數據：

復制代碼代碼如下:

<%@ 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)
            {
                //此處省略得到數據列表的代碼
                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 = "出錯";
        }
        context.Response.Write(resultStr);
    }
    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}