Tutorial: Your first Java EE application

Create a new Java Enterprise project

IntelliJ IDEA includes a dedicated wizard for creating Java Enterprise projects based on various Java EE and Jakarta EE implementations. In this tutorial, we will create a simple web application.

1. In the main menu, go to File | New | Project.

2. In the New Project dialog, select Jakarta EE.

3. Enter a name for your project: JavaEEHelloWorld.

4. Select the Web application template, Maven as a build tool, and use Oracle OpenJDK 17 as the project SDK. Don't select or add an application server, we will do it later.

   Click Next to continue.

   

5. In the Version field, select Jakarta EE 10 because that's what Tomcat 10.1 used in this tutorial is compatible with.

   In the Version field, select Jakarta EE 9.1 because that's what GlassFish 6.2.5 used in this tutorial is compatible with.

   In the Dependencies list, you can see that the web application template includes only the Servlet framework under Specifications.

   

   

6. Click Create.

Explore the default project structure

IntelliJ IDEA creates a project with some boilerplate code that you can build and deploy successfully.

• pom.xml is the Project Object Model with Maven configuration information, including dependencies and plugins necessary for building the project.

  <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.example</groupId> <artifactId>JavaEEHelloWorld</artifactId> <version>1.0-SNAPSHOT</version> <name>JavaEEHelloWorld</name> <packaging>war</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.target>11</maven.compiler.target> <maven.compiler.source>11</maven.compiler.source> <junit.version>5.10.0</junit.version> </properties> <dependencies> <dependency> <groupId>jakarta.servlet</groupId> <artifactId>jakarta.servlet-api</artifactId> <version>6.0.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>3.4.0</version> </plugin> </plugins> </build> </project>
  <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.example</groupId> <artifactId>JavaEEHelloWorld</artifactId> <version>1.0-SNAPSHOT</version> <name>JavaEEHelloWorld</name> <packaging>war</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.target>11</maven.compiler.target> <maven.compiler.source>11</maven.compiler.source> <junit.version>5.9.2</junit.version> </properties> <dependencies> <dependency> <groupId>jakarta.servlet</groupId> <artifactId>jakarta.servlet-api</artifactId> <version>5.0.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>3.3.2</version> </plugin> </plugins> </build> </project>

• index.jsp is the starting page of your application that opens when you access the root directory URL. It renders Hello World! and a link to /hello-servlet.

  <%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %> <!DOCTYPE html> <html> <head> <title>JSP - Hello World</title> </head> <body> <h1><%= "Hello World!" %> </h1> <p/> <a href="hello-servlet">Hello Servlet</a> </body> </html>

• The HelloServlet class extends HttpServlet and is annotated with @WebServlet. It processes requests to /hello-servlet: a GET request returns HTML code that renders Hello World!.

  package com.example.demo; import java.io.*; import javax.servlet.http.*; import javax.servlet.annotation.*; @WebServlet(value = "/hello-servlet") public class HelloServlet extends HttpServlet { private String message; public void init() { message = "Hello World!"; } public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { response.setContentType("text/html"); // Hello PrintWriter out = response.getWriter(); out.println("<html><body>"); out.println("<h1>" + message + "</h1>"); out.println("</body></html>"); } public void destroy() { } }

Use the Project tool window to browse and open files in your project or press Ctrl+Shift+N and type the name of the file.

Configure the application server

Let IntelliJ IDEA know where the GlassFish Tomcat application server is located.

1. Press Ctrl+Alt+S to open the IDE settings and then select Build, Execution, Deployment | Application Servers.

2. Click and select Glassfish Server Tomcat.

3. Specify the path to the GlassFish Tomcat server install location. IntelliJ IDEA detects and sets the name and version appropriately.

   

   

Create a run configuration

IntelliJ IDEA needs a run configuration to build the artifacts and deploy them to your application server.

1. In the main menu, go to Run | Edit Configurations.

2. In the Run/Debug Configurations dialog, click , expand the Glassfish Server Tomcat Server node, and select Local.

3. Fix any warnings that appear at the bottom of the run configuration settings dialog.

   

   Most likely, you will need to fix the following:

   • On the Server tab, set the Server Domain to domain1.

   • On the Deployment tab, add the artifact that you want to deploy: JavaEEHelloWorld:war exploded

4. On the Server tab, set the URL to point to the root resource:

   http://localhost:8080/JavaEEHelloWorld_war_exploded/

   

   

5. Click OK to save the run configuration.

6. To run the configuration, press Alt+Shift+F10 and select the created application server configuration.

   Alternatively, if you have your run configuration selected in the main toolbar at the top, you can click in the main toolbar or press Shift+F10 to run it.

This run configuration builds the artifacts, then starts the GlassFish Tomcat server, and deploys the artifacts to the server. You should see the corresponding output in the Services tool window.

Once this is done, IntelliJ IDEA opens the specified URL in your web browser.

If not, try opening the URL yourself: http://localhost:8080/RestGlassfishHelloWorld-1.0-SNAPSHOT/api/hello-world

If not, try opening the URL yourself: http://localhost:8080/RestTomcatHelloWorld_war_exploded/api/hello-world

Modify the application

Whenever you change the source code of the application, you can restart the run configuration to see the changes. But this is not always necessary, especially when you can't restart the server. Most of the changes are minor and don't require rebuilding the artifacts, restarting the server, and so on. Let's change the JSP page of the application.

1. Open index.jsp and change the greeting from Hello, World! to A better greeting.

2. In the Run tool window, click or press Ctrl+F10.

3. In the Update dialog, select Update resources because the JSP page is a static resource. Click OK.

4. Refresh the application URL in your web browser to see the new string: A better greeting.

You can configure the default update action in the run configuration settings: go to Run | Edit Configurations in the main menu. Change the On 'Update' action option under the Server tab of the GlassFish Tomcat run configuration settings.

With the On frame deactivation option, you can configure to update your resources and classes without redeploying and restarting the server whenever you change focus from IntelliJ IDEA. In this case, you won't even have to use the Update Application action, just switch to your web browser and refresh the page.

Package the application into a WAR and deploy it on a running server

In the previous steps, we deployed the application using an exploded artifact, where all files are uncompressed. This is useful during the first stages of development because it allows you to update individual resources and classes without redeploying. When you are happy with your application and ready to share it with others by deploying to a remote server, it is better to use the compressed web archive (WAR) format.

Let's add a Remote GlassFish Remote Tomcat run configuration to deploy the WAR artifact to a running server. This assumes that you did not terminate the running server from the previous steps.

1. In the main menu, go to Run | Edit Configurations.

2. In the Run/Debug Configurations dialog, click , expand the GlassFish Server Tomcat node, and select Remote.

3. Change the name of this run configuration to distinguish it, for example: Remote GlassFish 6.2.5 Remote Tomcat 10.1.5.

4. Open the Deployment tab, click above the table of artifacts to deploy, and select Artifact. Select to deploy the JavaEEHelloWorld:war artifact and click OK.

   

   

5. Click OK to save the remote run configuration.

6. Open index.jsp and change the greeting to Hello from WAR!.

7. Select the new run configuration in the main toolbar and click or press Shift+F10.

   

   

The new configuration builds the WAR artifact and deploys it to the running server. Refresh the URL http://localhost:8080/JavaEEHelloWorld-1.0-SNAPSHOT/ and see the new greeting: Hello from WAR!