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We've seen that Gradle is used for managing our dependencies, or the libraries that our application will depend on. In this video, we'll utilize a Gradle plugin that will allow us to launch our application on a running web server.
Dependency Management with Gradle
For more information on getting up & running with Gradle, check out our workshop at teamtreehouse.com/library/dependency-management-with-gradle.
Gradle Version 3 and up
Current versions of Gradle no longer use the buildscript syntax. The Spring Boot plugin syntax has also changed. Here is a working Gradle build script for more recent versions of Gradle:
plugins {
id 'java'
id 'idea'
id 'eclipse'
id 'org.springframework.boot' version '1.4.3.RELEASE'
}
group 'com.teamtreehouse'
version '1.0-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile 'org.springframework.boot:spring-boot-starter-web'
}
So we've had a chance to see
Spring from 30,000 feet,
0:00
and there might be some information there
that's not entirely clear at this point.
0:03
No worries, though,
0:08
we'll shed more light on each of those
areas as we work through the application.
0:09
What I'd like to do now is get Giflib
fully set up to use Spring, and configure
0:14
our Gradle build file to allow us to run a
web server with the application installed.
0:19
You should've already worked through
our Java annotations course.
0:24
Because annotations are the primary
means by which we'll configure our app,
0:28
it'll be useful to have some knowledge and
experience in working with them.
0:32
Okay, let's get started
with our configuration.
0:36
I'm back in IntelliJ with our giflib
project open that we created in
0:40
the first stage.
0:43
The first take we'll tackle is setting up
our Gradle build files that we not only
0:45
have the libraries necessary
to compile our code, but
0:48
also the tools necessary to deploy or
run our app in a web server.
0:51
So let's look at our Gradle build file and
0:56
remind ourselves of what
we already have in place.
0:58
At the top, we have a group and version of
the artifact that our build would create.
1:02
Just like how we imported a JAR file,
we can also build a JAR file for export so
1:07
that others may use it.
1:12
The details of the JAR file we could
generate as what we're seeing with
1:14
the group and the version.
1:17
Then we have this command
to apply the Java plugin.
1:19
In Gradle, plugins are extensions
of the Gradle tool itself and
1:23
add functionality to Gradle's
built-in features, which
1:26
is exactly what a plugin for any piece of
software would do, extend functionality.
1:30
Beyond dependency management, Gradle
allows you to accomplish many more tasks.
1:35
For example, compiling your code,
executing your code, testing your code or
1:39
building your project for deployment.
1:44
The Java plugin adds to Gradle the ability
to compile different source sets.
1:46
For example, it can compile and
run your main code or compile and
1:52
run your test code separately.
1:55
If you've taken our unit testing course,
you know how useful and
1:58
important it is to write text code
against your application code.
2:01
Gradle can assist in compiling and
running only your test code, or
2:05
it can do the same thing for
only your main application code.
2:09
This leads us to the next step
we'll take in our application.
2:12
The Java plugin expects our main
2:15
application code to appear
in a specific directory.
2:18
Namely, source main Java.
2:21
So let's go ahead and create that now.
2:24
To do that, we'll right-click on
the project and choose New > Directory.
2:27
In the prompt that comes up,
2:33
we'll type src/main/java.
2:37
And there we see the directory
popup in the directory tree of
2:42
our IntelliJ project.
2:45
We'll add a package and
some code to this directory in just a bit.
2:47
What we'll do next is update our
dependencies so that instead of simply
2:51
including a spring-webmvc library, we'll
also include what's needed to start our
2:55
application and auto-configure
it to run in a live web server.
3:00
To do this we're going to use another
Spring library called Spring Boot.
3:05
Among other things, Spring Boot
allows us to create a stand-alone,
3:09
runnable Spring application that
has an embedded web server.
3:14
There's a handful of ways to set up
the configuration of a Spring web app, but
3:18
this is the simplest way.
3:22
To leverage Spring Boot in our Java code,
we'll need its JAR file.
3:24
So we'll replace the dependency
we have with this one.
3:27
The group ID is org.springframework.boot,
3:31
the artifact ID is
spring-boot-starter-web,
3:37
and the release is 1.2.6.RELEASE.
3:43
You might be wondering why I replaced
the previous entry instead of just
3:47
adding another entry.
3:51
This is simply because the Spring Web MVC
library is a dependency of
3:53
spring-boot-starter-web.
3:57
So Gradle will automatically
download Spring Web MVC
3:58
anyway without us having
to explicitly list it.
4:02
Let's save our build file and
4:05
refresh our dependencies to see all
the libraries that get pulled in.
4:07
Remember, if you don't see
the gradial tool window,
4:10
go to View > Tool windows > Gradial.
4:14
I'll click refresh here.
4:16
And then, when you check out
the external libraries, you'll see that
4:19
quite a few have been added to your class
path, once they all get downloaded.
4:23
Again, thanks to Gradle, we don't need
to grab all of these libraries manually.
4:27
And there they are,
look at how those grew.
4:34
Just to point out a couple additions,
you'll see a bunch of
4:38
libraries from the Spring boot group,
including spring-boot-starter-tomcat.
4:41
We scroll through here we should see that.
4:46
Here's spring-boot-starter-tomcat.
4:49
Tomcat is the name of the Apache web
server that can run Java applications.
4:53
There is one more task we'll need to
complete in the build.gradle file
4:58
before moving on to Java code.
5:02
We need the ability to deploy our
web application during development.
5:04
Deployment refers to the process of
taking all of our compiled code and
5:08
necessary libraries and launching our
application in its target environment,
5:11
which in our case is a web server,
tomcat, as we see here.
5:15
Guess what?
5:19
Gradle can help with this too.
5:20
Spring boot has its own Gradle plugin
that can deploy a Spring application with
5:22
a web server.
5:26
But this plugin is not built into Gradle,
so
5:28
we'll need to add it to what's
called a buildscript in our file.
5:30
So we do this by typing the following,
let me give myself more room to work here.
5:34
Above the applied plugin line I'm
going to add a buildscript block.
5:41
Inside the buildscript block, I'll list
the repository that we're going to use to
5:47
grab any plugins that we might need
that aren't built in to Gradle itself.
5:51
MavenCentral is again the place
where we're gonna grab this.
5:58
Now, to grab the actual dependency for
this Spring boot plugin that we need,
6:02
I need to list that as
a dependency in the build script.
6:08
So another dependencies block.
6:13
Again, this one is separate from
the dependencies block of our
6:14
application code down here.
6:17
This is a dependencies block for
the plugin that we wanna grab.
6:19
And on the classpath,
6:22
I wanna put org.springframework.boot:.
6:25
Again, the artifact id,
spring-boot-gradle-plugin.
6:31
Intuitively named for us.
6:38
1.2.6.RELEASE.
6:39
And we'll save that.
6:43
Finally, in order to make use of
the additional plugin functionality,
6:46
we need another apply plugin entry.
6:50
This time for the spring-boot plugin.
6:54
Apply plugin: spring-boot.
6:56
We'll save that.
6:59
This will allow us to run what's called the Gradle task that will compile and
7:01
deploy our application in
an embedded web server.
7:06
If you expand the Tasks entry
in the Gradle tool window,
7:10
you'll see a bunch of categorized
tasks that you can run using Gradle.
7:14
For example, if you expand other,
you'll see a task named compileJava.
7:18
Which, if you were to run,
7:24
would simply compile all of the code
in your source/main/Java directory.
7:26
Now that we've applied the Spring Boot
plugin, let's hit Refresh.
7:30
You should see this
application item pop in there,
7:35
which comes from the Spring boot plugin.
7:38
There it is right there.
7:40
In a bit, we'll be using the boot run
task to build and deploy our application.
7:42
Next, we'll create a Java class that will
serve as our main configuration file for
7:48
this application.
7:52
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