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:

db4o测试 by 菩提树下的杨过

 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