C# で Datatable を Json に変換するための 5 つのコード例

实例一：

/// <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 = StringFormat(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();
    }
    /// <summary>
    /// 格式化字符型、日期型、布尔型
    /// </summary>
    /// <param name="str"></param>
    /// <param name="type"></param>
    /// <returns></returns>
    private static string StringFormat(string str, Type type)
    {
        if (type == typeof(string))
        {
            str = String2Json(str);
            str = "\"" + str + "\"";
        }
        else if (type == typeof(DateTime))
        {
            str = "\"" + str + "\"";
        }
        else if (type == typeof(bool))
        {
            str = str.ToLower();
        }
        else if (type != typeof(string) && string.IsNullOrEmpty(str))
        {
            str = "\"" + str + "\"";
        }
        return str;
    }
    /// <summary>
    /// 过滤特殊字符
    /// </summary>
    /// <param name="s">字符串</param>
    /// <returns>json字符串</returns>
    private static string String2Json(String s)
    {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.Length; i++)
        {
            char c = s.ToCharArray()[i];
            switch (c)
            {
                case &#39;\"&#39;:
                    sb.Append("\\\""); break;
                case &#39;\\&#39;:
                    sb.Append("\\\\"); break;
                case &#39;/&#39;:
                    sb.Append("\\/"); break;
                case &#39;\b&#39;:
                    sb.Append("\\b"); break;
                case &#39;\f&#39;:
                    sb.Append("\\f"); break;
                case &#39;\n&#39;:
                    sb.Append("\\n"); break;
                case &#39;\r&#39;:
                    sb.Append("\\r"); break;
                case &#39;\t&#39;:
                    sb.Append("\\t"); break;
                default:
                    sb.Append(c); break;
            }
        }
        return sb.ToString();
    }

 实例二：

 public static string CreateJsonParameters(DataTable dt)
        {
            /**//**/
            /**//* /****************************************************************************
          * Without goingin to the depth of the functioning of this Method, i will try to give an overview
          * As soon as this method gets a DataTable it starts to convert it into JSON String,
          * it takes each row and in each row it grabs the cell name and its data.
          * This kind of JSON is very usefull when developer have to have Column name of the .
          * Values Can be Access on clien in this way. OBJ.HEAD[0].<ColumnName>
          * NOTE: One negative point. by this method user will not be able to call any cell by its index.
         * *************************************************************************/
            StringBuilder JsonString = new StringBuilder();
            //Exception Handling        
            if (dt != null && dt.Rows.Count > 0)
            {
                JsonString.Append("{ ");
                JsonString.Append("\"T_blog\":[ ");
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    JsonString.Append("{ ");
                    for (int j = 0; j < dt.Columns.Count; j++)
                    {
                        if (j < dt.Columns.Count - 1)
                        {
                            JsonString.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + "\"" + dt.Rows[i][j].ToString() + "\",");
                        }
                        else if (j == dt.Columns.Count - 1)
                        {
                            JsonString.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + "\"" + dt.Rows[i][j].ToString() + "\"");
                        }
                    }
                    /**//**/
                    /**//*end Of String*/
                    if (i == dt.Rows.Count - 1)
                    {
                        JsonString.Append("} ");
                    }
                    else
                    {
                        JsonString.Append("}, ");
                    }
                }
                JsonString.Append("]}");
                return JsonString.ToString();
            }
            else
            {
                return null;
            }
        }

效果：
{"T_blog":
  [
   {"id":"14","title":"北京奥运开幕式","addtime":"2008-08-08"},
   {"id":"15","title":"网络文化","addtime":"2008-09-12"},
   {"id":"17","title":"北京下雨了","addtime":"2008-09-19"},
   {"id":"21","title":"深圳地铁通了","addtime":"2008-09-25"}
  ]
}

实例三：

/// <summary>
    /// 将一个数据表转换成一个JSON字符串，在客户端可以直接转换成二维数组。
    /// </summary>
    /// <param name="source">需要转换的表。</param>
    /// <returns></returns>
    public static string DataTableToJson(DataTable source)
    {
        if (source.Rows.Count == 0)
            return "";
        StringBuilder sb = new StringBuilder("[");
        foreach (DataRow row in source.Rows)
        {
            sb.Append("[");
            for (int i = 0; i < source.Columns.Count; i++)
            {
                sb.Append(&#39;"&#39; + row[i].ToString() + "\",");
            }
            sb.Remove(sb.Length - 1, 1);
            sb.Append("],");
        }
        sb.Remove(sb.Length - 1, 1);
        sb.Append("]");
        return sb.ToString();
    }

    /// <summary>
    /// 反回JSON数据到前台
    /// </summary>
    /// <param name="dt">数据表</param>
    /// <returns>JSON字符串</returns>
    public string CreateJsonParameters(DataTable dt)
    {
        StringBuilder JsonString = new StringBuilder();
        //Exception Handling        
        if (dt != null && dt.Rows.Count > 0)
        {
            JsonString.Append("{ ");
            JsonString.Append("\"TableInfo\":[ ");
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                JsonString.Append("{ ");
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    if (j < dt.Columns.Count - 1)
                    {
                        JsonString.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + "\"" + dt.Rows[i][j].ToString() + "\",");
                    }
                    else if (j == dt.Columns.Count - 1)
                    {
                        JsonString.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + "\"" + dt.Rows[i][j].ToString() + "\"");
                    }
                }
                /**/
                /*end Of String*/
                if (i == dt.Rows.Count - 1)
                {
                    JsonString.Append("} ");
                }
                else
                {
                    JsonString.Append("}, ");
                }
            }
            JsonString.Append("]}");
            return JsonString.ToString();
        }
        else
        {
            return null;
        }
    }

实例四：

public class DataTableConvertJson
    {
        #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();
        }
    }

实例五：

#region  DataTable 转换为Json字符串实例方法
/// <summary>
/// GetClassTypeJosn 的摘要说明
/// </summary>
public class GetClassTypeJosn : IHttpHandler
{
    /// <summary>
    /// 文件名:DataTable 和Json 字符串互转
    /// 版权所有:Copyright (C) Create Family Wealth liangjw
    /// 创建标示：2013-08-03
    /// </summary> 
    //用法说明实例
     public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "application/json";
        context.Response.Charset = "utf-8";
        HttpRequest req = context.Request;
        string method = req["method"].ToStr().ToLower();

       //获取合同明细列表  DataTable 转换为Json字符串
        if (method == "txtdate")
        {
            string json = "";
            BO.MakeContractMx bll = new MakeContractMx();
            DataSet ds = bll.GetDataTable();
            if (ds.Tables.Count > 0)
            {
                json =ToJson(ds.Tables[0]);
            }
            context.Response.Write(json);
            return;
        }
    }
   public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}
   #endregion
    #region Json字符串转换为DataTable 实例方法
    public DataTable JsonToDataTable(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

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