把Java对象映射成XML文档，这是Java对象持久化的一种新思路。在XML.com的一篇文章里，作者对四种主要的Java-XML映射工具进行了全面的比较：
Breeze XML Binder, a tool produced by Breeze Factor
Castor, an open source project under ExoLab
JAXB Reference Implementation, created by SUN
XGen, a tool produced by Commerce One.
比较的标准主要有以下几条：（1）对XML大纲（schema）特性的支持程度；（2）生成Java代码的可用性；（3）Java-XML转换（以及反向转换）的工作情况。
测试的结果如下。可以看到，Sun的JAXB参考实现竟然有着绝佳的表现，不论在性能还是特性集方面，都仅次于XGen，名列第二。这让我对JAXB又多了几分信心。
Feature
Breeze
Castor
JAXB RI
XGen
Customization Disallowed
Package Name Mapped from Namespace
Automatic Unmarshaling
Open Source
Free of Charge
Schema Location Roundtrippable
Schema Location Settable
Schemas without a Target Namespace Supported
Instance Validation on Unmarshal
Constraint Check of Values on Set
5
Value Validation when Marshaling
5
Code Generation Command Line Tool Interface
Code Generation Programmatic Interface
Code Generation GUI Interface
Generated Code Implements Generic Interfaces
1 -- Mapped if no other package name is specified.
2-- JAXB will be available as an open source project in the upcoming future. More information can be found at http://jaxb.dev.java.net/.
3 -- Only on marshaller class.
4 -- Off by default.
5 -- Some values validated.
6 -- Interfaces based on functionality instead of type of XML Schema construct.
