大家好，又见面了，我是你们的朋友全栈君。

官网软件下载可能过慢，以下为我的分享：

db4o-8.0-java.zip (包含db4o的API及jar包，以及OME插件等)： http://pan.baidu.com/s/1gdBx13X

Eclipse分享（适合OME插件的Eclipse版本）：http://pan.baidu.com/s/1kTEDgf9

Welcome

db4o is the native Java, .NET and Mono open source object database.

db4o是本地的Java，.NET和Mono的开源对象数据库.

This tutorial was written to get you started with db4o as quickly as possible. Before you start, please make sure that you have downloaded the latest db4o distribution from the db4objects website.

写这份指南是为了让你能够对db4o尽快上手。在开始之前，请首先确保你已经从db4objects的网站上下载了最新的db4o发行包。

developer.db4o.com

You are invited to join the db4o community in the public db4o forums to ask for help at any time.

你被邀请加入db4o社区的公共论坛，在那里可以随时请求帮助。

Links

In order to access free developer resources you may want to register on db4o developer website.

Feel free register to the forums http://www.db4o.com/Users/register.aspx.

为了可以访问免费的开发者资源，你可能需要在db4o开发者网站上要注册一个账号，论坛的注册网址为：http://www.db4o.com/Users/register.aspx

And here are some further links on developer.db4o.com that you may find useful:

下面是一些 developer.db4o.com 上的一些可能对你比较有用的链接：

All Downloads

SVN Repository

Community Projects

Download Contents(下载内容)

The db4o Java distribution comes as one zip file, db4o-8.0-java.zip. When you unzip this file, you get the following directory structure:

db4o的Java发布版本是以一个zip文件（db4o-8.0-java.zip）的形式进行发布的。解压缩这个文件后，你将获得下面的目录结构：

Please take a look at all the supplied documentation formats to choose the one that works best for you:

.请看一下所有的文档格式，选择一个最适合你的：

db4o-8.0/doc/api/index.html

The API documentation for db4o is supplied as JavaDocs HTML files. While you read through this tutorial it may be helpful to look into the API documentation occasionally.

db4o的API文档以JavaDocs的HTML文件格式提供。当你阅读这份指南的时候，偶尔翻阅一下这个API文档是很有帮助的。

db4o-8.0/doc/reference/index.html

The reference documentation is a complete compilation for experienced db4o users.

参考文档是对有经验的db4o用户来说是一个完整的编辑物。

db4o-8.0/doc/tutorial/index.html

This is the interactive HTML tutorial. Examples can be run “live” against a db4o database from within the browser. In order to use the interactive functionality a Java JRE 1.3 or above needs to be installed and integrated into the browser. Java security settings have to allow applets to be run. If you have problems using the interactive functionality, please refer to Tutorial Troubleshooting.

这是交互式的HTML的指南。示例可以依靠一个db4o数据库在浏览器上实时运行。为了使用交互功能：你需要安装一个1.3或更新版本的JRE并把它集成到浏览器里。Java的安全设置必须允许运行applet，如果你在使用交互功能的时候遇到了问题，请参考指南的Tutorial Troubleshooting 部分。

db4o-8.0/doc/tutorial/db4o-8.0-tutorial.pdf

The PDF version of the tutorial allows best fulltext search capabilities.

这份PDF版本的指南很好的支持全文检索功能。

1. First Glance （开始前的了解）

Before diving straight into the first source code samples let’s get you familiar with some basics.

在进入第一个示例代码之前，让我们先了解一些必要的基础知识。

1.1. The db4o engine （db4o引擎）

The db4o object database engine consists of one single core jar file. In addition you may want to use client/server library or optional components. You may also get it all in a single jar “db4o-all”:

do4o对象数据库引擎由一个Jar文件组成。另外你可能想要使用客户机/服务器库或可选组件，其实你都可以在一个jar包（ db4o-all）中得到你想要的。

db4o-8.0-core-java1.1.jar

will run with most Java JDKs that supply JDK 1.1.x functionality such as reflection and Exception handling. That includes many IBM J9 configurations, Symbian and Savaje.

运行在大部分支持JDK1.1特性（如反射及异常处理）的java JDK，其中包括了一些IBM J9 configurations,Symbian 和 Savaje。

db4o-8.0-core-java1.2.jar

is built for all Java JDKs between 1.2 and 1.4.

用于1.2 至1.4 版本的Java JDK。

db4o-8.0-core-java5.jar

is built for Java JDK 5 and JDK 6

用于1.5 至1.6 版本的Java JDK。

If you intend to use client/server version of db4o you will additionally need client/server library

如果你想要使用客户端/服务器版本的db4o，你可能需要额外的一些客户端/服务器的包

matching your JDK version（对应你的jdk版本）:

db4o-8.0-cs-java1.1.jar

db4o-8.0-cs-java1.2.jar

db4o-8.0-cs-java5.jar

Some advanced functionality such as cluster support, platform-specific IO adapters,

statistic tools etc can be added by including db4o optional library:

一些高级的功能，例如集群支持，特定于平台的IO适配器，统计工具等也可以通过添加db4o可选包支持。

db4o-8.0-optional-java1.1.jar

db4o-8.0-optional-java1.2.jar

db4o-8.0-optional-java5.jar

You can also get all of the above in a single jar:

你也可以通过一个jar包，获得以上所有的功能支持。

db4o-8.0-all-java1.1.jar

db4o-8.0-all-java1.2.jar

db4o-8.0-all-java5.jar

1.2. Installation（安装）

If you add one of the above db4o-*.jar files to your CLASSPATH db4o is installed. For beginners it is recommended to use “db4o-all” library to avoid confusion with the location of certain classes. In case you work with an integrated development environment like Eclipse you would copy the db4o-*.jar to the /lib/ folder under your project and add db4o to your project as a library.

只要把上面的 db4o-*.jar中的某个添加到CLASSPATH中，就算完成了db4o的安装。初学者建议使用“db4o-all”库,以避免对于某些类的位置混淆。假如你使用像Eclipse这样的IDE，那么就应该把 db4o-*.jar复制到项目文件夹中的lib目录下，并把db4o作为一个代码库加到你的项目当中。

1.3. Object Manager Enterprise installation(OME)

Object Manager Enterprise (OME) is an object browser for db4o databases. OME installation can be found in /ome folder of the distribution. The zip file in this folder contains the Eclipse plugin version of OME.

OME是db4o数据库的一个对象浏览器，它的安装可以在/ome文件夹下的介绍中找到，这个文件夹下的zip压缩文件包含了Eclipse的OME插件版本。

To install the plugin, you need to have a version of Eclipse >= 3.3 installed. Unzip the file to a folder of your choice. Then open Eclipse, select ‘Help’ -> ‘Software Updates…’ -> ‘Available Software’ from the menu. Choose ‘Add Site…’ -> ‘Local…’ and select the unzipped folder. Follow the Eclipse Update Manager instructions for the OME feature from here on.

插件的安装，你压根安装一个版本在3.3以上的Eclipse，然后把文件解压到你指定的目录，打开 Eclipse，在菜单栏选择‘Help’ -> ‘Software Updates…’ -> ‘Available Software’ ，选择’Add Site…’ -> ‘Local…’ ，然后选择解压的文件，在这里遵循Eclispe对于OME特性的更新管理指令。

The actual menu structure may vary over Eclipse versions. (The above applies to Eclipse 3.4 Ganymede.) When in doubt, please refer to the Eclipse documentation on Software Updates.

Alternatively, you can install the plugin manually by simply copying the contents of the ‘plugins’ and ‘features’ folders from the unzipped folder to the corresponding subfolders in the root folder of your Eclipse installation.

实际的菜单结构在Eclipse版本可能会有所不同。(以上适用于Eclipse 3.4 Ganymede)。如果有疑问,请参阅Eclipse文档软件更新。

1.4. API Overview（API预览）

Do not forget the API documentation while reading through this tutorial. It provides an organized view of the API, looking from a java package perspective and you may find related functionality to the theme you are currently reading up on.

For starters, the java packages com.db4o and com.db4o.query are all that you need to worry about.

请在阅读本指南的时候，不要忘记API文档。它从Java包（package）的角度出发提供了有组织的API视图，你可以在阅读本指南的同时使用它方便地找到与主题相关的功能。

首先，com.db4o、com.db4o.query是我们所需要关心的。

com.db4o

The com.db4o java package contains almost all of the functionality you will commonly need when using db4o. Two objects of note are com.db4o.Db4oEmbedded, and the com.db4o.ObjectContainer interface.

com.db4o包含了几乎所有通常所需要用到的功能。其中有两个值得留意的接口：com.db4o.Db4o和com.db4o.ObjectContainer。

The com.db4o.Db4o factory is your starting point. Static methods in this class allow you to open a database file and create an initial configuration. For client/server environment you will need to use com.db4o.cs.Db4oClientServer factory class to start a server, or connect to an existing server, but this will be discussed later , start a server, or connect to an existing server. The most important interface, and the one that you will be using 99% of the time is com.db4o.ObjectContainer: This is your db4o database.

而com.db4o.Db4o工厂类是我们进行开发的起始点，该类的静态方法提供了打开数据库文件、创建初始化的配置的功能。对于客户端/服务器的环境，你可能需要用com.db4o.cs.Db4oClientServer工厂类来启动服务或者连接到已有的服务器的功能，这将会稍后讨论。com.db4o.ObjectContainer是一个99%的时间都会用到的、最重要的接口：在开发过程中，它就是你的db4o数据库。

– An ObjectContainer can either be a database in single-user mode or a client connection to a db4o server.

– Every ObjectContainer owns one transaction. All work is transactional. When you open an ObjectContainer, you are in a transaction, when you commit() or rollback(), the next transaction is started immediately.

– Every ObjectContainer maintains it’s own references to stored and instantiated objects. In doing so, it manages object identities, and is able to achieve a high level of performance.

– ObjectContainers are intended to be kept open as long as you work against them. When you close an ObjectContainer, all database references to objects in RAM will be discarded.

– ObjectContainer可以作为单用户模式的数据库，也可以作为db4o服务器的客户端连接。
– 每个ObjectContainer持有一个事务，所有的操作都是事务相关的。当你打开一个ObjectContainer时，事务已经开始了，当你commit()或者rollback()，它将会马上启动下一个事务。
– 每个ObjectContainer会自己管理那些被其存储并实例化的对象的引用。而做这些工作的同时，它还管理这对象的唯一标识，这样是它能够达到很高的性能。
– 在使用ObjectContainer的过程中，只要你还在使用它，它就会一直保持打开状态。而当你关闭这个ObjectContainers时，所有保存在内存中的对象引用都将被丢弃掉。

com.db4o.ext

In case you wonder why you only see very few methods in an ObjectContainer, here is why: The db4o interface is supplied in two steps in two java packages, com.db4o and com.db4o.ext for the following reasons:

也许你会问为什么ObjectContainer里面只有那么少的方法，原因是将db4o接口被分别放置在com.db4o和com.db4o.ext这两个包中，这么做是为了：

– It’s easier to get started, because the important methods are emphasized.

– It will be easier for other products to copy the basic db4o interface.

– It is an example of how a lightweight version of db4o could look.

– 便于快速开始，因为重要的方法都在ObjectContainer中被强调了。

– 其他产品更容易复制db4o的基本接口。

– 很好地展现了一个db4o的轻量级版本。

Every com.db4o.ObjectContainer object is also an com.db4o.ext.ExtObjectContainer. You can cast it to ExtObjectContainer or you can use the method to get to the advanced features.

每个com.db4o.ObjectContainer对象同时也是一个com.db4o.ext.ExtObjectContainer对象。你可以把它转换成ExtObjectContainer，或者可以使用方法来获得更高级的特性。

com.db4o.config

The com.db4o.config java package contains types and classes necessary to configure db4o. The objects and interfaces within are discussed in the Configuration section.

com.db4o.config包里面包含了配置db4o所需的类型和类，我们将在配置章节中讨论它的对象和接口。

com.db4o.query

The com.db4o.query java package contains the Predicate class to construct Native Queries. The Native Query interface is the primary db4o querying interface and should be preferred over the Soda Query API.

com.db4o.query包中包含了用来构造原生查询的Predicate类。Native Query接口是db4o最主要的查询接口，并且它应该比Soda查询API更常用。