You can use any Java compatible libraries with the Java runtime on theApp Engine flexible environment.These instructions use Apache Maven to build, run, and deploy a sample app usingasupported Javaruntime. For more information about using supported Java versions, see theJava runtime.

Declare and manage dependencies

To manage dependencies using Maven, you need to specify the dependencies inthe<dependencies> section inside thepom.xmlfile of your project.

To manage your project's dependency on Maven itself, you can use theMaven Wrapper. If you do not use theMaven Wrapper, App Engine defaults to using a recent version of Mavenwhen runninggcloud app deploy.

Specify the Java servlet library

Eclipse Jetty and Tomcat apps require the Java servlet library. Specify it inyourpom.xml file's<dependencies> entry:

<dependency><groupId>com.example.appengine</groupId><artifactId>simple-jetty-main</artifactId><version>1</version><scope>provided</scope></dependency>

Use the Cloud Client Libraries

Cloud Client Libraries for Javaprovide idiomatic access to Google Cloud services. To use a library, declareit as a dependency.

Typically, you only declare dependencies on the specific libraries that your appneeds. For example, to use the Cloud Storage library:

<!--Usinglibraries-bomtomanageversions.Seehttps://github.com/GoogleCloudPlatform/cloud-opensource-java/wiki/The-Google-Cloud-Platform-Libraries-BOM--><dependencyManagement><dependencies><dependency><groupId>com.google.cloud</groupId><artifactId>libraries-bom</artifactId><version>26.28.0</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>com.google.cloud</groupId><artifactId>google-cloud-storage</artifactId></dependency></dependencies>

You can configure the Cloud Client Libraries for Java tohandle authentication automatically.