DataConvertJson

    public class DataConvertJson
    {

        #region dataTable转换成Json格式
        /// <summary>  
        /// dataTable转换成Json格式  
        /// </summary>  
        /// <param name="dt"></param>  
        /// <returns></returns>  
        public static string DataTable2Json(DataTable dt)
        {
            StringBuilder jsonBuilder = new StringBuilder();
            jsonBuilder.Append("{"");
            jsonBuilder.Append(dt.TableName);
            jsonBuilder.Append("":[");
            jsonBuilder.Append("[");
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                jsonBuilder.Append("{");
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    jsonBuilder.Append(""");
                    jsonBuilder.Append(dt.Columns[j].ColumnName);
                    jsonBuilder.Append("":"");
                    jsonBuilder.Append(dt.Rows[i][j].ToString());
                    jsonBuilder.Append("",");
                }
                jsonBuilder.Remove(jsonBuilder.Length - 1, 1);
                jsonBuilder.Append("},");
            }
            jsonBuilder.Remove(jsonBuilder.Length - 1, 1);
            jsonBuilder.Append("]");
            jsonBuilder.Append("}");
            return jsonBuilder.ToString();
        }

        #endregion dataTable转换成Json格式
        #region DataSet转换成Json格式
        /// <summary>  
        /// DataSet转换成Json格式  
        /// </summary>  
        /// <param name="ds">DataSet</param> 
        /// <returns></returns>  
        public static string Dataset2Json(DataSet ds)
        {
            StringBuilder json = new StringBuilder();

            foreach (DataTable dt in ds.Tables)
            {
                json.Append("{"");
                json.Append(dt.TableName);
                json.Append("":");
                json.Append(DataTable2Json(dt));
                json.Append("}");
            }
            return json.ToString();
        }
        #endregion

        /// <summary>
        /// Msdn
        /// </summary>
        /// <param name="jsonName"></param>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static string DataTableToJson(string jsonName, DataTable dt)
        {
            StringBuilder Json = new StringBuilder();
            Json.Append("{"" + jsonName + "":[");
            if (dt.Rows.Count > 0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    Json.Append("{");
                    for (int j = 0; j < dt.Columns.Count; j++)
                    {
                        Json.Append(""" + dt.Columns[j].ColumnName.ToString() + "":"" + dt.Rows[i][j].ToString() + """);
                        if (j < dt.Columns.Count - 1)
                        {
                            Json.Append(",");
                        }
                    }
                    Json.Append("}");
                    if (i < dt.Rows.Count - 1)
                    {
                        Json.Append(",");
                    }
                }
            }
            Json.Append("]}");
            return Json.ToString();
        }
    }