今天下午开始接触db4o,遇到了一个很诡异的问题,下面是具体代码:

=====================

using System;
using System.IO;
using Db4objects.Db4o;

namespace Db4object
{
    public class StuInfo
    {
        public string StuName { get; set; }
        public int StuAge { get; set; }

        override public string ToString()
        {
            return string.Format("{0} / {1}" , StuName , StuAge);
        }
    }

    public class FirstStepsExample
    {
        public static void Main(string[] args)
        {
            IObjectContainer db = Db4oFactory.OpenFile("c:\\data.dbf");

            InsertManyData(db);
            RetrieveAllData(db);

            db.Dispose();

            Console.ReadKey();
        }

        public static void InsertManyData(IObjectContainer db)
        {
            for (int i = 0 ; i < 1000 ; i++)
            {
                StuInfo info = new StuInfo() { StuName = "name :" + i , StuAge = i };
                db.Store(info);
            }
        }

        public static void RetrieveAllData(IObjectContainer db)
        {
            IObjectSet result = db.Query(typeof(StuInfo));
            ListResult(result);
        }

        private static void ListResult(IObjectSet result)
        {
            Console.WriteLine("total count :{0}" , result.Count);

            foreach (StuInfo item in result)
                Console.WriteLine(item);
        }
    }
}

=====================

第一次运行,InsertManyData()插入数据成功,RetrieveAllData()成功将全部数据读出,但是当去掉InsertManyData()再次运行时(此时data.dbf已有了数据),但是RetrieveAllData()就不能读取任何数据了(total count :0).

ps:db4o是最新的官方版本