using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Web.Script.Serialization;
using System.Collections;

namespace CommonLib {

    /// <summary>
    /// JSON转换帮助类
    /// </summary>
    public static class JsonUtil {

        #region Json字符串转换为DataTable 实例方法
        public static DataTable JsonToDataTable(String json) {
            DataTable dt = ToDataTable(json);
            return dt;
        }
        #endregion

        #region DataTable 转换为Json 字符串
        /// <summary>
        /// DataTable 对象 转换为Json 字符串
        /// </summary>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static string ToJson(this DataTable dt) {
            JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();
            javaScriptSerializer.MaxJsonLength = Int32.MaxValue; //取得最大数值
            ArrayList arrayList = new ArrayList();
            foreach (DataRow dataRow in dt.Rows) {
                Dictionary<string, object> dictionary = new Dictionary<string, object>();  //实例化一个参数集合
                foreach (DataColumn dataColumn in dt.Columns) {
                    dictionary.Add(dataColumn.ColumnName, dataRow[dataColumn.ColumnName].ToStr());
                }
                arrayList.Add(dictionary); //ArrayList集合中添加键值
            }

            return javaScriptSerializer.Serialize(arrayList);  //返回一个json字符串
        }
        #endregion

        #region Json 字符串 转换为 DataTable数据集合
        /// <summary>
        /// Json 字符串 转换为 DataTable数据集合
        /// </summary>
        /// <param name="json"></param>
        /// <returns></returns>
        public static DataTable ToDataTable(this string json) {
            DataTable dataTable = new DataTable();  //实例化
            DataTable result;
            try {
                JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();
                javaScriptSerializer.MaxJsonLength = Int32.MaxValue; //取得最大数值
                ArrayList arrayList = javaScriptSerializer.Deserialize<ArrayList>(json);
                if (arrayList.Count > 0) {
                    foreach (Dictionary<string, object> dictionary in arrayList) {
                        if (dictionary.Keys.Count<string>() == 0) {
                            result = dataTable;
                            return result;
                        }
                        if (dataTable.Columns.Count == 0) {
                            foreach (string current in dictionary.Keys) {
                                dataTable.Columns.Add(current, dictionary[current].GetType());
                            }
                        }
                        DataRow dataRow = dataTable.NewRow();
                        foreach (string current in dictionary.Keys) {
                            dataRow[current] = dictionary[current];
                        }

                        dataTable.Rows.Add(dataRow); //循环添加行到DataTable中
                    }
                }
            }
            catch {

            }
            result = dataTable;
            return result;
        }
        #endregion

        #region 转换为string字符串类型
        /// <summary>
        ///  转换为string字符串类型
        /// </summary>
        /// <param name="s">获取需要转换的值</param>
        /// <param name="format">需要格式化的位数</param>
        /// <returns>返回一个新的字符串</returns>
        public static string ToStr(this object s, string format = "") {
            string result = "";
            try {
                if (format == "") {
                    result = s.ToString();
                }
                else {
                    result = string.Format("{0:" + format + "}", s);
                }
            }
            catch {
            }
            return result;
        }
        #endregion
    }
}