C#将Access数据库导出为JSON

一个Access数据库包含若干首诗歌，每首诗有content、author、title、description四个字段

using System;
using System.Data;
using System.Data.OleDb;
using System.Runtime.Serialization.Json;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Runtime.Serialization;
[DataContract]
struct Poem {
    [DataMember]
    public string content { get; set; }
    [DataMember]
    public string author { get; set; }
    [DataMember]
    public string title { get; set; }
    [DataMember]
    public string description { get; set; }
}
class Haha {
    public static void Main() {
        string url = "Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source=C:\Users\weidiao\Desktop\data.mdb";
        OleDbConnection con = new OleDbConnection(url);
        con.Open();
        OleDbCommand command = new OleDbCommand("select * from t_poetry", con);
        OleDbDataReader reader = command.ExecuteReader();
        Console.WriteLine(reader.FieldCount);
        FileStream cout = new FileStream("poem.json", FileMode.Create);
        List<Poem> li = new List<Poem>();
        while (reader.Read()) {
            Poem p = new Poem();
            p.author = reader["d_author"].ToString();
            p.content = reader["d_poetry"].ToString();
            p.description = reader["d_intro"].ToString();
            p.title = reader["d_title"].ToString();
            li.Add(p);
        }
        String s = ObjectToJson(li);
        byte[] bytes = Encoding.UTF8.GetBytes(s);
        cout.Write(bytes, 0, bytes.Length);
        cout.Close();
        con.Close();
    }
    // 从一个对象信息生成Json串
    public static string ObjectToJson(object obj) {
        DataContractJsonSerializer serializer = new DataContractJsonSerializer(obj.GetType());
        MemoryStream stream = new MemoryStream();
        serializer.WriteObject(stream, obj);
        byte[] dataBytes = new byte[stream.Length];
        stream.Position = 0;
        stream.Read(dataBytes, 0, (int)stream.Length);
        return Encoding.UTF8.GetString(dataBytes);
    }
}