POJO的解释（最接近出处，目前所见最准确）_pojo is not specialed please bind a pojo-优快云博客

POJO（Plain Old Java Object）是Martin Fowler等人创造的一个术语，指普通的Java对象，它不是Java Bean、Entity Bean或Session Bean等特殊角色。POJO可以运行在EJB容器中，它们对于创建领域模型非常有用。

http://c2.com/cgi/wiki?PlainOldJavaObject

Plain Old Java Object

POJO = "Plain Old Java Object". Term coined by MartinFowler, RebeccaParsons ?, and JoshMacKenzie to denote a normal Java object that is not a JavaBean , an EntityBean , a SessionBean , etc., and does not serve any other special role or implement any special interfaces of any of the Java frameworks (EJB, JDBC, DAO, JDO, etc...). Any Java object can run within an EJB container, but many people don't know that or forget it. Fowler et al invented the acronym POJO so that such objects would have a "fancy name", thereby convincing people that they were worthy of use. POJOs are useful for creating a DomainModel. In contrast, the various types of beans and other special Java objects often have constraints that make it difficult to use them directly to model a domain.

I see a tendency of people fudging that definition of POJO because their ObjectRelationalMapping products obviously do not support POJO persistence, as they would like to announce. The typical case is referring to the JSR-220 (EJB3, JDO2) as "POJO persistence", when the EJB 3.0 early draft makes it clear that it is only a "Simplification of the enterprise bean types. Enterprise beans are simplified to more closely resemble plain Java objects ("POJOs") or JavaBeans." -- KlausWuestefeld

For real POJO persistancy have a look at PersistedObjectTree unlike KlausWuestefeld's Prevayler it lets you use any type of data structure. -- Bjorn Blomqvist