Simple Jetty HelloWorld Webapp

With the jetty-maven-plugin and Servlet Annotations, it has never been simpler to start developing with Jetty! While we have not quiet achieved the terseness of some convention over configuration environments/frameworks/languages, it is getting close and only 2 files are needed to run a web application!

Maven pom.xml

A minimal maven pom.xml is need to declare a dependency on the Servlet API and use the jetty-maven-plugin.   A test project and pom.xml can be created with:

$ mkdir demo-webapp
$ cd demo-webapp
$ gedit pom.xml

The pom.xml file is still a little verbose and the minimal file needs to be at least:

<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 http://maven.apache.org/maven-v4_0_0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <packaging>war</packaging>
   <groupId>org.eclipse.jetty.demo</groupId>
   <artifactId>jetty-helloworld-webapp</artifactId>
   <version>1.0</version>
   <dependencies>
     <dependency>
       <groupId>javax.servlet</groupId>
       <artifactId>javax.servlet-api</artifactId>
       <version>3.1.0</version>
       <scope>provided</scope>
     </dependency>
   </dependencies>
   <build>
     <plugins>
       <plugin>
         <groupId>org.eclipse.jetty</groupId>
         <artifactId>jetty-maven-plugin</artifactId>
         <version>9.4.5.v20170502</version>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-war-plugin</artifactId>
         <version>3.0.0</version>
         <configuration>
           <failOnMissingWebXml>false</failOnMissingWebXml>
         </configuration>
       </plugin>
     </plugins>
   </build>
</project>

Annotated HelloWorld Servlet

Maven conventions for Servlet development are satisfied by creating the Servlet code in following source directory:

$ mkdir -p src/main/java/com/example
$ gedit src/main/java/com/example/HelloWorldServlet.java

Annotations allows for a very simple Servlet file that is mostly comprised of imports:

package com.example;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet(urlPatterns = {"/*"}, loadOnStartup = 1)
public class HelloWorldServlet extends HttpServlet
{
 @Override
 public void doGet(HttpServletRequest request, HttpServletResponse response)
 throws IOException
 {
 response.getOutputStream().print("Hello World");
 }
}

Running the Web Application

All that is left to do is to run the web application:

$ mvn jetty:run

You can then point your browser at http://localhost:8080/ to see your web application!

Next Steps

OK, not the most exciting web application, but it is a start.  From here you could:

• Clone this demo from github.
• Add more Servlets or some Filters
• Add static content in the src/main/webapp directory
• Create a web deployment descriptor in src/main/webapp/WEB-INF/web.xml
• Build a war file with mvn install