【三】zTree 异步加载 C# + ashx +DataTable

JS文件如下：

 var setting = {

    async: {
        //异步加载
        enable: true,
        url: getUrl
    },
    callback: {
        beforeExpand: beforeExpand,
        onAsyncSuccess: onAsyncSuccess,
        onAsyncError: onAsyncError
    }
};

function createTree() {
    $.ajax({
        url: 'Handler.ashx?action=GetProvince', //url  action是方法的名称
        data: { id: "0" },
        type: 'POST',
        dataType: "text", //可以是text，如果用text，返回的结果为字符串；如果需要json格式的，可是设置为json
        ContentType: "application/json; charset=utf-8",
        success: function(data) {
            $.fn.zTree.init($("#treeDemo"), setting, eval('(' + data + ')'));
        },
        error: function(msg) {
            alert("数据加载失败！");
        }
    });
}

function getUrl(treeId, treeNode) {
    var param = "id=" + treeNode.id ;
    return "Handler.ashx?action=GetProvince&" + param;
}
function beforeExpand(treeId, treeNode) {
    if (!treeNode.isAjaxing) {
        return true;
    } else {
        alert("zTree 正在下载数据中，请稍后展开节点。。。");
        return false;
    }
}

function onAsyncSuccess(event, treeId, treeNode, msg) {}
function onAsyncError() {
    alert("数据加载失败");
}

$(document).ready(function () {
    createTree();
});

 Handler.ashx

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

using System;
using System.Web;

public class Handler : IHttpHandler {
    
    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "text/plain";
        string method = context.Request["action"];
        switch (method)
        {
            case "GetModule":
                {
                    string parentID = context.Request.Params["id"]; //参数为id
                    zTree zTree = new zTree();

                    context.Response.Write(zTree.GetModule());
                    break;
                }
            case "GetModule1":
                {
                    string parentID = context.Request.Params["id"]; //父节点id
                    zTree zTree = new zTree();

                    context.Response.Write(zTree.GetModule1(parentID));
                    break;
                }
            case "GetProvince":
                {
                    string[] para = context.Request.Params["id"].Split(',');
                    string parentID = para[0]; //父节点id
                    string areaCategory = "";
                    if (para.Length > 1)
                    {
                        areaCategory = para[1];
                    }
                    
                    zTree zTree = new zTree();
                    context.Response.Write(zTree.GetProvince(parentID, areaCategory));
                    break;
                }
            default:
                break;
        }
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }

}

 CS文件

数据库表为省市区三张表，网上到处都是，找找下载去吧。

 public string GetProvince(string parentID, string areaCategory)
    {
        string treeJson = "";
        string sql = "";
        if (areaCategory.Trim() == "省")
            sql =
                @"SELECT c.City Name, c.CityCode+','+'市' ID,c.ProvinceCode ParentID,CASE WHEN(SELECT COUNT(1) FROM Area a(nolock) WHERE c.CityCode =a.CityCode)>0 THEN 'true' ELSE 'false' END isParent FROM City c(nolock)  WHERE c.ProvinceCode='" +
                parentID + "'";
        else if (areaCategory.Trim() == "市")
            sql =
                @"SELECT a.Area Name, a.AreaCode+','+'区' ID,a.CityCode ParentID,'false' isParent FROM Area a(nolock) WHERE a.CityCode='" +
                parentID + "'";
        else
            sql =
                @"SELECT p.Province Name,p.ProvinceCode+','+'省' ID,'0' ParentID,CASE WHEN(SELECT COUNT(1) FROM City c(nolock) WHERE p.ProvinceCode =c.ProvinceCode)>0 THEN 'true' ELSE 'false' END isParent FROM Province p(nolock) ";
        

        DataTable dt = Common.GetTable(sql);
        if (dt.Rows.Count > 0)
        {
            treeJson = DtToJson1(dt, "ParentID", parentID, "ID", "Name", "isParent").Substring(12);
        }
        return treeJson;

    }

/// <summary>
    /// 将DataTable转为zTree的Json格式
    /// </summary>
    /// <param name="dt">要转化的表</param>
    /// <param name="pField">表中的父节点字段</param>
    /// <param name="pValue">表中顶层节点的值,没有 可以输入为0</param>
    /// <param name="kField">关键字字段名称</param>
    /// <param name="TextField">要显示的文本 对应的字段</param>
    /// <param name="isParent">是否有子节点，主要通过sql实现</param>
    /// <returns></returns>
    public static string DtToJson1(DataTable dt, string pField, string pValue, string kField, string TextField, string isParent)
    {
        StringBuilder sb = new StringBuilder();
        string filter = String.Format(" {0}='{1}' ", pField, pValue); //获取顶级目录.
        DataRow[] drs = dt.Select(filter);
        if (drs.Length < 1)
            return "";
        sb.Append(",\"children\":[");
        foreach (DataRow dr in drs)
        {
            string pcv = dr[kField].ToString();
            sb.Append("{");
            sb.AppendFormat("\"name\":\"{0}\",", dr[TextField].ToString());
            sb.AppendFormat("\"id\":\"{0}\",", dr[kField].ToString());
            sb.AppendFormat("\"isParent\":\"{0}\"", dr[isParent].ToString());

            sb.Append(DtToJson(dt, pField, pcv, kField, TextField).TrimEnd(','));
            sb.Append("},");
        }
        if (sb.ToString().EndsWith(","))
        {
            sb.Remove(sb.Length - 1, 1);
        }
        sb.Append("]");
        return sb.ToString();
    }