Better Faster Lighter Java [Electronic resources] نسخه متنی

Chapter 9. Simple Spider

I once had the pleasure of building a house with a carpenter who was
from Mexico; I learned a great deal in the process. Despite my broken
Spanish (I once twisted the language so badly that I told him that I
was going home to marry my sister), he was able to impart an
incredible amount of wisdom. My observations were, shall we say...
less wise. I told him that I was proud of my hammer. It had a sleek
and heavy head, and a composite graphite handle that made it easy to
swing. The head was waffled so it would grip the nails. He simply
chuckled. At the end of the day, he had used his 10-year-old,
plain-Jane hammer to drive in four times the nails as I did, with
more accuracy and precision. He told me, "No esta el
martillo:" it's not the hammer.

Luckily, I build code better than I build houses. In this chapter, I
continue to put the five basic principles into action. I create a
simple service with a light user interface to drive it. The service
is an open source web indexer, primarily used to provide site search
behavior for a single web site. It is

called Simple Spider and is available at
http://www.relevancellc.com/halloway/SimpleSpiderl.

I'll give you an insider's view of
the real client requirements that spawned the application in the
first place. The requirements were minimal and straightforward, but
there was still a lot of work to do to understand the problem space.
Notice large functionality areas that could be built for this
application or reused from other tools; 'll walk you
through the decision-making process that led us to use or discard
each one. You'll also see the ways our desire for
simplicity and our selection of the right tools
led to the first iteration of the Spider. In the next chapter, I
extend jPetStore to use the Spider. I do this
while focusing on the use of transparency to enable extensibility.

Throughout both these chapters, I constantly apply the principle of
focus: do one thing, and do it well. You want to build a simple
hammer, one that fits like a glove in the hand of a skilled
carpenter. That desire affects everything, from the requirements to
the design to the individual lines of code you write. Along the way,
I aim a spear at a variety of sacred cows, from over-burdensome
frameworks and over-expensive data formats to notions about how
technologies like JUnit and HTTPUnit should be used. In the end,
you'll have an open source application and a greater
appreciation for how good programming in Java can be if you just keep
your wits about you.