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Adding a Spring Configuration File
5:16In this video, we'll add the minimum required configuration details for Spring, so that upon launching our application, all components are properly discovered.
We've gotten a few things set up in
our Spring application, but we've yet
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to write even a single line of Java code.
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Hang on though we're almost there.
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It's time to write the configuration
file for our application.
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Throughout the years Spring has
offered a variety of methods for
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configuring a Spring
application starting with XML.
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Then to what's called Java config,
and finally Spring boot.
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Check the teacher's notes for
links to the first two.
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In this course,
we'll be using Spring boot.
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Of the three approaches,
it's the simplest to implement.
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Alright, let's configure our app.
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To configure our app,
first we need to create our base package,
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under which we'll put
all of our Java code.
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We'll create this under
source main Java and
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call it com dot team treehouse dot giflib.
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So I will right click the Java folder,
choose new,
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package and
type com dot team treehouse dot giflib.
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In this package we'll create
a Java class called app config,
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though it really could be
named anything you like.
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So, right click,
new Java class called app config.
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I'm going to delete this
default comment block in here.
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And because this going to
be a runnable application,
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I'm guessing you know exactly which
method I'll need to add to this class.
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Yep, it's a main method.
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Public static void main.
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String array args.
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Wonderful.
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In the main method, we're going to call
a method from the spring boot library that
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will run our application,
creating a new application context.
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The class is called spring application.
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Now we get the suggestion here for
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spring application because the Spring
boot library is on our class path.
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Gradle took care of that for us.
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When you're using an IDE, and
in Java in general, you can import any
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class that's on your class path whether
it came from the Java core library or
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some sort of third party
library like spring boot.
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Spring application, I'll choose enter and
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IntelliJ will automatically drop
in that import statement for me.
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And the method we want to call is run,
and I'll choose our current class,
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.class, passing it the args
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parameter that was passed to the main
method, and I'll save that class.
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Finally, in order for
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spring to be auto configured, we'll
need to add an annotation to this class.
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This annotation is called quite
intuitively enable auto configuration.
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Also coming from the spring framework.
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And that's all we'll need to have
a spring application that's deployable to
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a web server.
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Let's give it a whirl.
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What you'll want to do at this point is,
in the Gratde tool window,
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expand tasks, and expand application,
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right click on boot run,
and choose run gitflib.
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>> You should see some output that
includes a fancy plain text Spring logo at
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the top, and you should see in there
that Tomcat, which is our web server,
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was initialized, eventually was started,
and finally that app config started.
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Here you see the app config
started in 2.067 seconds.
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Now that our application is
running in a live web server,
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let's switch over to a browser and
check it out.
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In your favorite browser, I'm using Chrome
here, you can find the local web server by
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typing local host colon, 8080, which
is the port number in the address bar.
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I'll hit enter, and yay, there it is.
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I know, you might be thinking,
this dude's crazy.
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He got an error message,
and he's happy about it.
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And you'd be right, about both parts.
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But actually, this does indicate we were
successful in running a web server and
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deploying our application
to the web server.
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You see this message here that says this
application has no explicit mapping for
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slash error?
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So you are seeing this as a fallback?
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All that means is that we have no code
in our application that could handle
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the URL requested,
which is essentially the home page.
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So, it returns the error page
which we also haven't defined.
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Never fear though,
our next step will fix that.
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Congratulations on successfully
deploying your first Java web app.
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I know, the results may not be what you
were hoping for from your first app, but
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even without a complete application
you've done quite a bit.
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You've created a Spring application
in IntelliJ, configured Gradle
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which is one of the most widely used build
and dependency management tools, and you
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wrote a simple Spring configuration file
that leverages the Spring boot library
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to fire up your Spring web application and
deploy it on a running web server.
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That's pretty sweet.
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Even cooler is that we're about
to dive deep into coding giflib.
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Why don't you go through
a few questions and
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challenges before we really
tackle this application?
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I'll see you right back here for
some serious Spring coding.
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