[zz]Dion Almaer: Hibernate3 Example of Annotation Hell :)

I am getting to play with Hibernate 3, and they have done a nice job. I was poking around the Caveat Emptor example from Hibernate in Action, which was updated for Hibernate3.

I happened across this file: package-info.java:

[code:1]@TypeDefs({
@TypeDef(
name="monetary_amount_usd",
typeClass = MonetaryAmountType.class,
parameters = { @Parameter(name="convertTo", value="USD") }
),
@TypeDef(
name="monetary_amount_eur",
typeClass = MonetaryAmountType.class,
parameters = { @Parameter(name="convertTo", value="EUR") }
),
@TypeDef(
name="item_state",
typeClass = EnumUserType.class,
parameters = { @Parameter(name="enumClassName", value="org.hibernate.ce.auction.model.ItemState") }
),

@TypeDef(
name="creditcard_type",
typeClass = EnumUserType.class,
parameters = { @Parameter(name="enumClassName", value="org.hibernate.ce.auction.model.CreditCardType") }
),
@TypeDef(
name="rating",
typeClass = EnumUserType.class,
parameters = { @Parameter(name="enumClassName", value="org.hibernate.ce.auction.model.Rating") }
)
})

@NamedQueries({
@NamedQuery(
name="minBid",
queryString="select b from Bid b where b.amount.value = (select min(b.amount.value) from Bid b where b.item.id = :itemid)"
),
@NamedQuery(
name="maxBid",
queryString="select b from Bid b where b.amount.value = (select max(b.amount.value) from Bid b where b.item.id = :itemid)"
)
})

package org.hibernate.ce.auction.persistence;

import org.hibernate.annotations.*;
import javax.persistence.*;[/code:1]

Is this better than XML? To have this code sucked in?

NOTE: You don't have to use the annotations of course.

从提高效率、更方便的角度来看：
xDoclet、Annotation、XML都一样，一样的无能。
我觉的唯一可以依赖的就是GUI工具。当然，GUI工具可以基于XML和Annotation开发。
Annotation作为MetaData，算是稍胜其它方法的地方吧。

在没有GUI工具情况下，也不考虑动态使用Annotation，个人还是喜欢使用Annotation而不是XML，就是因为懒得一会java一会xml的。

一直比较反感annotation，把Java代码弄得不像代码的样子，看起来就不爽。

然则就算有了好的visual IDE，还是得把metadata保存在某个地方亚。总不能保存在IDE自己的数据库里面吧。

关键是耦合太深。就拿hibernate来说吧，若是用XML，数据库改个字段名，服务器这边只需要改XML文件；若是用annotation，就得改source code，然后recompile。关键是在server上要改东西很可能压根找不到source code，或者找到也不一定有环境编译，这就比较恶心了。