json與DataTable相互轉換

好一段時間沒有寫文章，最近剛搬家，家裏還沒裝上網絡，代碼農沒有網絡是蠻恐怖的一事件。

願歸正傳今天我想說的自定義json與DataTable相互轉換。相信大家都有看過微軟的.NET中實現JSON的API 的相應方法吧。首先我們看看 Newtonsoft.Json.JsonConvert 是怎麼完成的：

           DataTable table = new DataTable();
            table.Columns.Add("id");
            table.Columns.Add("name");
            table.Columns.Add("url");
            table.Rows.Add("1", "zhengdjin", "http://blog.csdn.net/zhengdjin");
            table.Rows.Add("2", "生活信息網", "http://www.naoqiu.com");

           //Newtonsoft.Json api：
            //序列化
            string api_s= Newtonsoft.Json.JsonConvert.SerializeObject(table);
            Console.WriteLine(api_s);
            //反序列化
            DataTable api_Table = Newtonsoft.Json.JsonConvert.DeserializeObject(api_s, typeof(DataTable)) as DataTable;
            Console.ReadLine();

實現的方式相當簡單，微軟都幫我處理掉那些繁雜的操作，那我們來還原將DataTable轉換爲Json格式的情景：

我爲了做更多的擴展，首先創建一個json基類代碼如下：

    /// <summary>
    /// json基類
    /// </summary>
    public abstract class IJson<T>
    {
        /// <summary>
        /// 行信息區域塊表示方式
        /// </summary>
        private string _rowInfo = "{}";
        /// <summary>
        /// 行分割字符
        /// </summary>
        private char _rowSp = ',';
        /// <summary>
        /// 列分割字符
        /// </summary>
        private char _columnSp = ',';

        /// <summary>
        /// 行分割字符
        /// </summary>
        public char RowSplit {
            get { return _rowSp; }
            set { _rowSp = value; }
        }
        /// <summary>
        /// 列分割字符
        /// </summary>
        public char ColumnSplit {
            get { return _columnSp; }
            set { _columnSp = value; }
        }
        /// <summary>
        /// 行信息區域塊表示方式
        /// </summary>
        public string RowInfo
        {
            get { return _rowInfo; }
            set { _rowInfo = value; }
        }

        /// <summary>
        /// 默認json轉化參數格式
        /// </summary>
        public IJson() : this(',', ',', "{}") { }

        public IJson(char rSplit, char cSplit, string rInfo)
        {
            this._rowSp=rSplit;
            this._columnSp = cSplit;
            this._rowInfo = rInfo;
        }

        /// <summary>
        /// 轉化爲json對象
        /// </summary>
        /// <typeparam name="T">對象類型</typeparam>
        /// <param name="t">參數</param>
        /// <returns></returns>
        public abstract string toJson<T>(T t);

        /// <summary>
        /// jsaon轉化對象
        /// </summary>
        /// <param name="json">jsaon字符</param>
        /// <returns>對象</returns>
        public abstract T toObject(string json);
    }

接下來定義一個JsontoDataTable 繼承json基類，然後實現 toJson<T>(T t) 將dataTable轉換爲json

/// <summary>
        /// dataTable轉化爲json對象
        /// </summary>
        /// <typeparam name="T">參數類型</typeparam>
        /// <param name="t">參數</param>
        /// <returns></returns>
        public override string toJson<T>(T t)
        {
            DataTable table = t as DataTable;
            if (table == null) return "";
            if (RowInfo.Length != 2) throw new NotImplementedException("行信息區域塊表示方式格式不正確");
            StringBuilder jsonBuilder = new StringBuilder();
            jsonBuilder.Append(table.TableName+":[");
            string head = "";
            int i = 0;
            foreach (DataColumn dc in table.Columns){
                head += dc.ColumnName + ":" + (dc.DataType == typeof(int) || dc.DataType == typeof(decimal) ?
                    "{" + i++.ToString() + "}" : "\"{" + i++.ToString() + "}\"") + ColumnSplit.ToString();
            }
            head = head.TrimEnd(ColumnSplit);
            foreach (DataRow dr in table.Rows){
                jsonBuilder.Append(RowInfo[0].ToString());
                jsonBuilder.AppendFormat(head, dr.ItemArray.ToArraybySpecial());
                jsonBuilder.Append(RowInfo[1].ToString() + RowSplit.ToString());
            }
            return jsonBuilder.ToString().Trim(RowSplit) + "]";
        }

到這裏已經完成了DataTable轉換爲json ,現在還差個將json轉化爲DataTable，這個方法相對難度比DataTable轉換json稍微。實現這個方法過程中我們得使用正則表達式來獲取數據（可參考asp.net如何加快頁面加載(三)——淺談正則應用）。

/// <summary>
        /// json轉化爲DataTable
        /// </summary>
        /// <param name="json">json變量</param>
        /// <returns>DataTable</returns>
        public override DataTable toObject(string json)
        {
            string pattern_row = @"(" + RowInfo[0] + "(.|\n)*?(" + RowInfo[1] + RowSplit +
                @")|" + RowInfo[0] + "(.|\n)*?(" + RowInfo[1] + @"\]))";
            //獲取行記錄
            MatchCollection matches = Regex.Matches(json, pattern_row);
            if (matches.Count == 0) return null;
            //獲取列名
            MatchCollection matches_columns = Regex.Matches(matches[0].Value, "(?<=[" + RowInfo[0].ToString() + ColumnSplit.ToString() + @"])[^\:]+");
            DataTable table = new DataTable();
            //綁定列名
            foreach (Match m in matches_columns) {
                table.Columns.Add(m.Value);
            }
            //綁定數據
            DataRow dr;
            string value;
            foreach (Match m in matches) {
                dr = table.NewRow();
                foreach (Match mc in matches_columns) {
                    value = Regex.Match(m.Value, "(?<=[" + RowInfo[0].ToString() + ColumnSplit.ToString() + "]+" + mc.Value + @"\:)[\d\.]+").Value;
                    if (value == "") {
                        value = Regex.Match(m.Value, "(?<=[" + RowInfo[0].ToString() + ColumnSplit.ToString() + "]+" +
                            mc.Value + @"\:\"")(.|\n)*?\""[" + ColumnSplit.ToString() + RowInfo[1].ToString() + "]").Value;
                    }
                    dr[mc.Value] = Regex.Replace(value, "\"[" + ColumnSplit.ToString() + RowInfo[1].ToString() + "]", "").toDesSpecial();
                }
                table.Rows.Add(dr);
            }
            return table;
        }

到這裏完成了json 與DataTable互轉的功能。

源碼下載地址：Json與DataTable互轉 

總結：微軟給了我們很大的方法，但同時也弱化我們的能力，其實我們只要掌握好基礎知識我們也可以寫出很漂亮的第三方控件，當然這個需要多去實踐多提高（我也是菜鳥）。