Embedded Tomcat Guide

Author: Malte B. P.
Last updated 12/06-2020

This is a very small example / guide on how to use an embedded Tomcat server instead of a standalone server Tomcat server.

Things to note:

• This guide assumes you're using Maven
• This guide assumes you're using IntelliJ
• This guide doesn't explain about JAX-RS/Jersey
• The project is a working example of an embedded Tomcat, and should be clonable and immediately runnable
• For a guide to standalone Tomcat server see this link

TLDR

1. Copy the properties, dependencies and build sections from the pom.xml in this project to the pom.xml in your project
2. Copy the Main class from this project to your project
3. Place your website content (html, css, js etc.) in src/main/webapp folder, or adjust WEBAPP_PATH in the Main class to the path of your website
4. Done!

Guide

1. Create a new Maven project or use an existing one.

2. Setup the pom.xml: You should copy the following from the pom.xml file in this project to your project:

• The <properties> ... </properties> section

  This supplies the pom with the tomcat.version property, which you may change in order to change the server version. It also tells Maven which Java version it should use for compilation.

• Tthe entire <dependencies>...<dependencies> section

  Only the dependencies tomcat-embed-core and tomcat-embed-jasper from org.apache.tomcat.embed are necessary to actually run the embedded Tomcat server. The remaining dependencies are for Jersey.

• The entire <build> ... </build> section

  This is not important for running the project from IntelliJ, but ensures that your become .jar-file becomes executable (this is also how your create an executable .jar file from any Maven project)

• Remember to reimport Maven!

3. Add the Main.java from this project to your project

This class contains the main method, you'll run to start Tomcat server, and deploys your content (i.e. website and Jersey application). If you place the class within a package, you should add the package name to the <mainClass>Main</mainClass> element in the build section of you pom.xml. I.e. Main.java has the path src/main/java/MyPackage/Main.java you would write <mainClass>MyPackage.Main</mainClass> .

4. Add content to your project:

• Place your website content (.html, .js etc.) within the folder src/main/java/webapp.

  If you use another folder, you should change the WEBAPP_PATH within the Main class to the same path (relative from project root)

• Place your class Application class and resource/service/endpoint classes as you usually do (somewhere in src/main/java)

5. Done! Running the project like a "regular" IntelliJ project will now start the Tomcat server and deploy your content to the server!

The project can be compiled to a .jar and run like any other Maven project. To do this open View -> Tool Windows -> Maven Projects. In the window that pops up, go into the Lifecycles"folder", select from clean to package(inclusive), and press the run icon (green arrow). This will build your .jar-file which anyone who has the correct version of Java installed should be able to run