Apache Maven is a build automation tool for Java. It is capable of building WAR files for deployment into App Engine. The App Engine team provides both a plugin and Maven Archetypes for the purpose of speeding up development.
Setting up Maven
To use Maven in the flexible environment:
Determine whether Maven is installed and which version you have, by invoking the following command:
This command should display a long string of information beginning with
Apache Maven 3.3.9.
If you don't have the proper version of Maven installed:
Install Google Cloud SDK.
Install the Cloud SDK app-engine-java component:
gcloud components install app-engine-java
If you want to start with a Java sample app, you can use this GitHub project.
Adding the App Engine Maven and Jetty Maven plugins
To use these plugins in an existing Maven project, add the following into the
plugins section in the project
<plugins> <plugin> <groupId>com.google.cloud.tools</groupId> <artifactId>appengine-maven-plugin</artifactId> <version>0.1.2</version> </plugin> <plugin> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-maven-plugin</artifactId> <version>9.3.7.v20160115</version> </plugin> </plugins>
Compile and build your project using Maven
To build an Java App Engine Web Application using Maven with its
Change to the main directory for your project, for example,
Wait for the project to build. When the project successfully finishes you will see a message similar to this one:
BUILD SUCCESS Total time: 10.724s Finished at: 2016-07-29T12:13:36-07:00 Final Memory: 24M/213M
Optionally, run and test the application locally using the Jetty web development server, as described in the next section.
Running and testing your app
During the development phase, you can run and test your app at any time in the development server by invoking the Jetty Maven plugin.
To run your app in the development server:
Build your app if you haven't already done so:
Change directory to the top level of your project (for example, to
myapp), and run your app by invoking Maven:
Wait for the server to start and use your browser to visit
http://localhost:8080/to access your app.
Shut down the app and the development server by pressing Control+C.
Deploying your app
After you add the App Engine Maven plugin to your project's
pom.xml file, you can deploy your application:
appengine:deploy goal and all other goals in the App Engine Maven plugin
have associated parameters that you can use. For a complete list, see
App Engine Maven Plugin Goals and Parameters.