DataSet 转成 JSON 操作类

using System;
using System.Collections.Generic;
using System.Web;
using System.Data;
using Newtonsoft.Json;
using System.Text;
using System.IO;

    /// <summary>
    ///JsonHelper 的摘要说明
    /// </summary>
    public class JsonHelper
    {
        public JsonHelper()
        {
            //
            //TODO: 在此处添加构造函数逻辑
            //
        }

        public static string DataTableToJSON(DataTable dt, string dtName)
        {
            StringBuilder sb = new StringBuilder();
            StringWriter sw = new StringWriter(sb);

            using (JsonWriter jw = new JsonTextWriter(sw))
            {
                JsonSerializer ser = new JsonSerializer();
                jw.WriteStartObject();
                jw.WritePropertyName(dtName);
                jw.WriteStartArray();
                foreach (DataRow dr in dt.Rows)
                {
                    jw.WriteStartObject();

                    foreach (DataColumn dc in dt.Columns)
                    {
                        jw.WritePropertyName(dc.ColumnName);
                        ser.Serialize(jw, dr[dc].ToString());
                    }

                    jw.WriteEndObject();
                }
                jw.WriteEndArray();
                jw.WriteEndObject();

                sw.Close();
                jw.Close();

            }

            return sb.ToString();
        }
    }