Maven 2 quirks and the "bandwagon"

I recently found myself developing (and using) a lot of small tag libraries to make my life easier when it comes to developing my web applications. The only thing that really gets me is that when I write these tag libraries, I have to manually update all of the TLD (tag library descriptor) files that are necessary for using the tags in JSPs. This irks me and it occurs to me that there's no reason I can't have Maven generate the TLDs for me based on annotations I place on the tag classes. The only problem with this is that no such plugin exists, so I figured that as a foray into Maven plugin development, I'd try making such a plugin as my first try. It is then that I ran across a rather large and bothersome quirk with Maven : it's not entirely ready for Java 5 and up. In fact, rather than using proper Java 5 annotations, it uses XDoclet comment annotations to provide metadata for building plugins, but that's not the quirk. The real quirk is that it can't handle having Java 5 annotations in the same project as the plugin. It can handle Java 5 enums just fine, but not annotations, which seems rather strange to me.

This is all part of the bigger problem of companies not keeping themselves up to date with the latest Java technology and staying with Java 1.4.2 and earlier. Sun has done a great job of maintaining backward compatibility, and there's (almost) no reason that companies shouldn't be upgrading the JVMs on their servers to the latest and greatest versions. The only real reason I can think of is that somewhere in their code, they've used variables named 'enum' which becomes a Java keyword in Java 5 and up (aka Java 1.5, 1.6, etc), and this can be mitigated by refactoring the code. Hell, Eclipse makes that job quick and easy, especially when you really know your keyboard shortcuts. I'm fortunate enough to be able to use Java 6 (and very quickly upgrade to Java 7 as soon as it's released and stable). As much as this is going to make me a snob, I'm getting really tired of being dragged down by other people's need for backward compatibility (and hence also tool developers' appeasement of these people which then affects me). Seriously people, get your act together.

Java enums are even cooler than I ever knew !

A quick note on Java enums : I discovered today that not only can enums have methods (which is exceedingly useful to begin with), but that you can individually override methods on a per-enum-value basis! That's so cool. I read it on this blog.

An interesting Spring Framework quirk

Recently, I discovered the joy of the PropertyEditorRegistrar interface in the Springframework, for conveniently registering property editors to bind between objects and text when rendering forms. This joy led me to discover an interesting quirk : if you subclass a Form Controller and register property editors that way, the object of a field will be bound to the BindStatus.value property, but if you use a PropertyEditorRegistrar, that value gets edited and the spring representation of it bound to BindStatus.value. This is a small distinction that makes a huge difference when writing (and rendering) your pages.

RSS and Me

I love RSS, I think it's a great way to read the news and generally stay up to date on any sites you read and any (legit) torrents you may want to download, or podcasts if that's your thing. I've been kicking around the idea of having an RSS notifier for our system at work, so that I wouldn't have to be sending out extraneous emails all over the place. According to this guy, creating an RSS feed is stupid simple. Maybe when I get the chance I'll give it a try.

*EDIT* : Ok, me being me, I was fascinated with the idea of dealing with something new and couldn't let it go. I followed one breadcrumb after another and found, fortunately for me, that Spring already has an (Abstract)RSS view class in the Spring Modules library that uses the Java Rome RSS library in the background. I can't wait to slog through the crap I have to deal with at the moment so that I can fool around with RSS and have RSS feeds supplying the notifications for our production system. This is going to save so many headaches.

*EDIT 2* : Heh, this guy's page is awesome. It shows that you can use security with RSS feeds, which will be perfect for my company.

Moar Hibernate !!!

Yet again, I'm posting because of fucking hibernate. One of the old quirks I had run across was that if you had a setter for a collection, ie :

public void setItems(List items)
{
this.items = items;
}

...this would replace the hibernate-backed collection that already existed (if one did) and could replace it with a non-hibernate implementation such as java.util.Vector, and any cached items would not get properly dealt with, and the collection would not get properly persisted, even to the point of throwing an exception. This resulted in me having to change my setters to this :

public void setItems(List items)
{
if(this.items == null)
{
this.items = items;
} else
{
this.items.clear();
this.items.addAll(items);
}
}

The only problem with this is that depending on the scenario, hibernate gets the collection, and then sets exactly the same list object back into the persistent entity we're dealing with, which would result in clearing exactly the same list we're trying to assign. The remedy :

public void setItems(List items)
{
if(this.items == null)
{
this.items = items;
} else if(this.items != items) //fix: identity check the two lists!
{
this.items.clear();
this.items.addAll(items);
}
}

That really should have been there anyway, but hibernate inspired it. Fuck you hibernate.

Spring and PropertyEditors, important details

As mentioned in the documentation, the Spring Framework uses property editors in two places:
1) When parsing ApplicationContexts from XML configuration files
2) When binding beans from HTTP requests.

It's all well and good if the only classes you need to bind are already covered by the editors built in with the Spring Framework, but if you need property editors for other kinds of classes, here's how to get Spring to include them, for both situations :
1) Use a CustomEditorConfigurer like so :

<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
<property name="customEditors">
<map>
<entry key="java.text.DateFormat">
<bean class="com.mypackage.CustomDateFormatEditor"/>
</entry>
<entry key="java.util.TimeZone">
<bean class="com.mypackage.TimeZoneEditor"/>
</entry>
<entry key="java.text.MessageFormat">
<bean class="com.mypackage.CustomMessageFormatEditor"/>
</entry>
<entry key="java.text.NumberFormat">
<bean class="com.mypackage.CustomNumberFormatEditor"/>
</entry>
</map>
</property>
</bean>

* Note * : The editors can be singletons because they're going to be the only instances needed by the application context to parse string values.

2) Implement and instantiate (or otherwise use) an implementation of PropertyEditorRegistrar. This will be used with your form controllers to register property editors for individual fields or whole types.

Ubuntu Linux is finally in the right place

I love Linux. Now, at this point, you're probably thinking that I'm just one of these fanboy nerds that loves to sit on a computer all day and hack on code. You're partially right : I do love to sit on computers and hack on code, but certainly not all day and certainly not at the expense of other fun activities like going to hockey games and being with friends. That said, I like Linux because it's good for doing development and it's ridiculously stable. It's even quite performant as well, which is
quite nice. I like it to the point that I'd want to put it on all of the computers here in the office, and as per the title of this post, I think that Ubuntu Linux is at the point where that's a practical possibility. In the past few days, I've installed Ubuntu 7.04 (Feisty Fawn) on two machines here in the office, set them up to do networked printing, networked file sharing, and everything else that may be needed by office workers. Hell, they can even use the built in Terminal Services client to remote into our server here in the office if they need to do any centralized work. They even have all their networked drives mounted for them, and they can see the Windows domain on which this place runs. The only thing remaining is for the systems to pass the Boss Test : sit the big boss of the company down on one, and if he can print his stuff, access his stuff and access our server exactly the same as he could in Windows, then it stays.

There's a great tutorial on setting up Samba with Windows Shares in Ubuntu here. Printing was
ridiculously easy to set up : I went to System -> Administration -> Printing , it autodetected the printers on our LAN and setting them up was merely a matter of following on screen directions.