Datatable转换为Json

        /// <summary>     
        /// Datatable转换为Json     
        /// </summary>    
        /// <param name="table">Datatable对象</param>     
        /// <returns>Json字符串</returns>     
        public static string ToJson(DataTable dt)
        {
            StringBuilder jsonString = new StringBuilder();
            jsonString.Append("[");
            DataRowCollection drc = dt.Rows;
            for (int i = 0; i < drc.Count; i++)
            {
                jsonString.Append("{");
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    string strKey = dt.Columns[j].ColumnName;
                    string strValue = drc[i][j].ToString();

                    Type type = dt.Columns[j].DataType;
                    jsonString.Append("\"" + strKey + "\":");
                    strValue = String.Format(strValue, type);
                    if (j < dt.Columns.Count - 1)
                    {
                        jsonString.Append("\"" + strValue + "\"" + ",");
                    }
                    else
                    {
                        jsonString.Append("\"" + strValue + "\"");
                    }
                }
                jsonString.Append("},");
            }
            jsonString.Remove(jsonString.Length - 1, 1);
            jsonString.Append("]");
            return jsonString.ToString();
        }