先上来代码：

 public static string DataTableToJSON(DataTable dt, string dtName){StringBuilder sb = new StringBuilder();StringWriter sw = new StringWriter(sb);using (JsonWriter jw = new JsonTextWriter(sw)){JsonSerializer ser = new JsonSerializer();jw.WriteStartObject();jw.WritePropertyName(dtName);jw.WriteStartArray();foreach (DataRow dr in dt.Rows){jw.WriteStartObject();foreach (DataColumn dc in dt.Columns){jw.WritePropertyName(dc.ColumnName);ser.Serialize(jw, dr[dc].ToString());}jw.WriteEndObject();}jw.WriteEndArray();jw.WriteEndObject();sw.Close();jw.Close();}return sb.ToString();}

例如上传一个dt  得到一个字符串

string jsonData = JsonHelper.DataTableToJSON(dt, "Products");

{"Products":[{"orderid":"11077","customerid":"RATTC","shipname":"Rattlesnake Canyon Grocery","shipcity":"Albuquerque","RowNumber":"1"},{"orderid":"11076","customerid":"BONAP","shipname":"Bon app'","shipcity":"Marseille","RowNumber":"2"},{"orderid":"11075","customerid":"RICSU","shipname":"Richter Supermarkt","shipcity":"Genève","RowNumber":"3"},{"orderid":"11074","customerid":"SIMOB","shipname":"Simons bistro","shipcity":"Kobenhavn","RowNumber":"4"},{"orderid":"11073","customerid":"PERIC","shipname":"Pericles Comidas clásicas","shipcity":"México D.F.","RowNumber":"5"},{"orderid":"11072","customerid":"ERNSH","shipname":"Ernst Handel","shipcity":"Graz","RowNumber":"6"},{"orderid":"11071","customerid":"LILAS","shipname":"LILA-Supermercado","shipcity":"Barquisimeto","RowNumber":"7"},{"orderid":"11070","customerid":"LEHMS","shipname":"Lehmanns Marktstand","shipcity":"Frankfurt a.M.","RowNumber":"8"},{"orderid":"11069","customerid":"TORTU","shipname":"Tortuga Restaurante","shipcity":"México D.F.","RowNumber":"9"},{"orderid":"11068","customerid":"QUEEN","shipname":"Queen Cozinha","shipcity":"Sao Paulo","RowNumber":"10"},{"orderid":"11067","customerid":"DRACD","shipname":"Drachenblut Delikatessen","shipcity":"Aachen","RowNumber":"11"},{"orderid":"11066","customerid":"WHITC","shipname":"White Clover Markets","shipcity":"Seattle","RowNumber":"12"},{"orderid":"11065","customerid":"LILAS","shipname":"LILA-Supermercado","shipcity":"Barquisimeto","RowNumber":"13"},{"orderid":"11064","customerid":"SAVEA","shipname":"Save-a-lot Markets","shipcity":"Boise","RowNumber":"14"},{"orderid":"11063","customerid":"HUNGO","shipname":"Hungry Owl All-Night Grocers","shipcity":"Cork","RowNumber":"15"},{"orderid":"11062","customerid":"REGGC","shipname":"Reggiani Caseifici","shipcity":"Reggio Emilia","RowNumber":"16"},{"orderid":"11061","customerid":"GREAL","shipname":"Great Lakes Food Market","shipcity":"Eugene","RowNumber":"17"},{"orderid":"11060","customerid":"FRANS","shipname":"Franchi S.p.A.","shipcity":"Torino","RowNumber":"18"},{"orderid":"11059","customerid":"RICAR","shipname":"Ricardo Adocicados","shipcity":"Rio de Janeiro","RowNumber":"19"},{"orderid":"11058","customerid":"BLAUS","shipname":"Blauer See Delikatessen","shipcity":"Mannheim","RowNumber":"20"}]}

很明显得到了一个json集合