db4o 7.4 for .net3.5试用手记

db4o虽然出来很久了，一直没怎么关注，今天随手试了下，对于小型应用还是不错的，至少省去了ORM的麻烦，一切皆对象，一切都变得那么自然。

下载地址:http://www.db4o.com/DownloadNow.aspx

优点:
1.使用简单，整个引擎只要一个dll(Db4objects.Db4o.dll)即能搞定(个人觉得可完全取代access用于某些小型应用)

2.数据库仅一个文件，方便部署
3.支持事务(文档上有提到的，不过我没测试过)
4.性能还过得去(10w以内的数据还可以接受，详见我的测试结果)
5.彻底忘记ORM吧，一切皆Object，还要什么ORM?
6.可同时用于.net与java平台

下面是测试代码:

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Diagnostics;

using Db4objects.Db4o;



namespace GetStarted

{

    class Program

    {

        static string DBFileName = "D:\\MyDoc\\db4o\\data\\demo.yap";



        static void Main(string[] args)

        {

            //如果文件已经存在，先删除(免得原来的记录影响测试结果)

            if (File.Exists(DBFileName)) { try { File.Delete(DBFileName); } catch (Exception e) { Console.WriteLine(e.Message.ToString()); } }



            IObjectContainer db = Db4oFactory.OpenFile(DBFileName);//打开数据库(如果数据库文件不存在，将自动创建)

            try

            {

                Pilot pilot1 = new Pilot("Michael Schumacher", 100);

                db.Store(pilot1);//对象存入数据库(即传统意义上的insert操作)

                Console.WriteLine("Stored {0}", pilot1);



                Pilot pilot2 = new Pilot("Rubens Barrichello", 99);

                db.Store(pilot2);//再存一个对象

                Console.WriteLine("Stored {0}", pilot2);



                Console.WriteLine("-----------------------------------------");



                Pilot proto = new Pilot(null, 0);//如果要查询出所有Pilot，创建一个"empty"的Pilot即可

                IObjectSet result = db.QueryByExample(proto);

                ListResult(result);



                Console.WriteLine("-----------------------------------------");



                Pilot proto1 = new Pilot("Rubens Barrichello", 0);//按Name查询(比如有意思的是：第二个参数随便什么都行，另外第一个参数是区分大小写的)

                IObjectSet result1 = db.QueryByExample(proto1);

                ListResult(result1);



                Console.WriteLine("-----------------------------------------");



                Pilot proto2 = new Pilot(null, 99);//按points查询

                IObjectSet result2 = db.QueryByExample(proto2);

                ListResult(result2);



                Console.WriteLine("-----------------------------------------");



                IList<Pilot> pilots = db.Query<Pilot>(typeof(Pilot));//泛型的查询方法，貌似写法更简单自然

                foreach (Pilot p in pilots)

                {

                    Console.WriteLine(p);

                }



                Console.WriteLine("-----------------------------------------");



                IList<Pilot> pilots2 = db.Query<Pilot>(new Predicate<Pilot>(c => c.Name == "Rubens Barrichello"));//按Name查询

                foreach (Pilot p in pilots2)

                {

                    Console.WriteLine(p);

                }



                Console.WriteLine("-----------------------------------------");

                //更新数据

                Pilot pilot3 = pilots2.FirstOrDefault();

                Console.WriteLine("before update：" + pilot3);

                pilot3.AddPoints(10);

                db.Store(pilot3);

                var _p = db.Query<Pilot>(new Predicate<Pilot>(c => c.Name == pilot3.Name)).FirstOrDefault();

                Console.WriteLine("after update：" + _p);



                Console.WriteLine("-----------------------------------------");



                //删除数据

                db.Delete(_p);

                IList<Pilot> listAfterDel = db.Query<Pilot>(typeof(Pilot));//显示删除后的所有对象

                foreach (Pilot p in listAfterDel)

                {

                    Console.WriteLine(p);

                }



                Console.WriteLine("-----------------------------------------");



                //大量数据插入测试                

                Stopwatch stopMatch = new Stopwatch();

                stopMatch.Start();

                int Count = 100000;//10w条数据

                for (int i = 0; i < Count; i++)

                {

                    Pilot pInsert = new Pilot(i.ToString(),i);

                    db.Store(pInsert);

                }

                stopMatch.Stop();

                Console.WriteLine("{0}条记录插入共耗时{1}毫秒", Count, stopMatch.ElapsedMilliseconds);



                stopMatch.Start();

                IList<Pilot> lstAll = db.Query<Pilot>(typeof(Pilot));

                stopMatch.Stop();

                Console.WriteLine("{0}条记录查询共耗时{1}毫秒", Count, stopMatch.ElapsedMilliseconds);



                stopMatch.Start();

                foreach (Pilot p in lstAll)

                {

                    p.AddPoints(1);

                    db.Store(p);

                }

                stopMatch.Stop();

                Console.WriteLine("{0}条记录更新共耗时{1}毫秒", Count, stopMatch.ElapsedMilliseconds);



                stopMatch.Start();

                foreach (Pilot p in lstAll)

                {                  

                    db.Delete(p);

                }

                stopMatch.Stop();

                Console.WriteLine("{0}条记录删除共耗时{1}毫秒", Count, stopMatch.ElapsedMilliseconds);



            }

            catch (Exception e)

            {

                Console.WriteLine(e.Message.ToString());

            }

            finally

            {

                db.Close();

            }



            Console.ReadLine();

        }





        static void ListResult(IObjectSet result)

        {

            Console.WriteLine(result.Count);

            foreach (object item in result)

            {

                Console.WriteLine(item);

            }

        }

    }





    public class Pilot

    {

        string _name;

        int _points;



        public Pilot(string name, int points)

        {

            _name = name;

            _points = points;

        }



        public string Name { get { return _name; } }



        public int Points { get { return _points; } }



        public void AddPoints(int points)

        {

            _points += points;

        }



        public override string ToString()

        {

            return string.Format("{0}/{1}", _name, _points);

        }

    }

}

本机运行结果:

Stored Michael Schumacher/100

Stored Rubens Barrichello/99

-----------------------------------------

2

Michael Schumacher/100

Rubens Barrichello/99

-----------------------------------------

1

Rubens Barrichello/99

-----------------------------------------

1

Rubens Barrichello/99

-----------------------------------------

Michael Schumacher/100

Rubens Barrichello/99

-----------------------------------------

Rubens Barrichello/99

-----------------------------------------

before update：Rubens Barrichello/99

after update：Rubens Barrichello/109

-----------------------------------------

Michael Schumacher/100

-----------------------------------------

100000条记录插入共耗时6176毫秒

100000条记录查询共耗时6189毫秒

100000条记录更新共耗时15861毫秒

100000条记录删除共耗时23730毫秒