/// <summary>      
        /// dataTable轉換成Json格式      
        /// </summary>      
        /// <param name="dt"></param>      
        /// <returns></returns>      
        public static string ToJson(DataTable dt)
        {
            StringBuilder jsonBuilder = new StringBuilder();
            jsonBuilder.Append(
 
"{\"");
            jsonBuilder.Append(dt.TableName.ToString());
            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();
        }


        /// <summary>      
        /// DataSet轉換成Json格式      
        /// </summary>      
        /// <param name="ds">DataSet</param>      
        /// <returns></returns>      
        public static string ToJson(DataSet ds)
        {
            StringBuilder json = new StringBuilder();

            foreach (DataTable dt in ds.Tables)
            {
                json.Append("{\"");
                json.Append(dt.TableName);
                json.Append("\":");
                json.Append(ToJson(dt));
                json.Append("}");
            }
            return json.ToString();
        }

.NET DataTable DataSet轉json代碼