Using Maven Jetty plugin

Pascal AlmaMarch 20th, 2013Last Updated: March 20th, 2013

1 78 3 minutes read

Although I am using Maven since a long time I never used the Jetty plugin until recently. To be able to test a REST client I created a servlet which showed me all incoming parameters and headers with the incoming request. To run the servlet in a container I decided to give the Maven Jetty plugin a go. So first I create a web application by using the specific Maven archetype:

mvn archetype:generate -DgroupId=net.pascalalma -DartifactId=rest-service -Dversion=1.0.0-SNAPSHOT -DarchetypeArtifactId=maven-archetype-webapp

This results in the complete project and the following logging:

[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] >>> maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom >>>
[INFO] 
[INFO] <<< maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom <<<
[INFO] 
[INFO] --- maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom ---
[INFO] Generating project in Interactive mode
Downloading: http://artifactory.redstream.nl/repo/org/apache/maven/archetypes/maven-archetype-webapp/1.0/maven-archetype-webapp-1.0.jar
Downloaded: http://artifactory.redstream.nl/repo/org/apache/maven/archetypes/maven-archetype-webapp/1.0/maven-archetype-webapp-1.0.jar (4 KB at 5.2 KB/sec)
Downloading: http://artifactory.redstream.nl/repo/org/apache/maven/archetypes/maven-archetype-webapp/1.0/maven-archetype-webapp-1.0.pom
Downloaded: http://artifactory.redstream.nl/repo/org/apache/maven/archetypes/maven-archetype-webapp/1.0/maven-archetype-webapp-1.0.pom (533 B at 1.1 KB/sec)
[INFO] Using property: groupId = net.pascalalma
[INFO] Using property: artifactId = rest-service
[INFO] Using property: version = 1.0.0-SNAPSHOT
[INFO] Using property: package = net.pascalalma
Confirm properties configuration:
groupId: net.pascalalma
artifactId: rest-service
version: 1.0.0-SNAPSHOT
package: net.pascalalma
 Y: : Y
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-webapp:1.0
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: net.pascalalma
[INFO] Parameter: packageName, Value: net.pascalalma
[INFO] Parameter: package, Value: net.pascalalma
[INFO] Parameter: artifactId, Value: rest-service
[INFO] Parameter: basedir, Value: /Users/pascal/projects
[INFO] Parameter: version, Value: 1.0.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: /Users/pascal/projects/rest-service
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 13.057s
[INFO] Finished at: Sun Feb 03 17:13:33 CET 2013
[INFO] Final Memory: 7M/81M
[INFO] ------------------------------------------------------------------------
MacBook-Air-van-Pascal:projects pascal$

Next I added the servlet code to the project:

package net.pascalalma.servlets;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
/**
 *
 * @author pascal
 */
public class TestRestServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        out.println('GET method called');
        out.println('parameters:\n ' + parameters(request));
        out.println('headers:\n ' + headers(request));
    }
 
    public void doPost(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        out.println('POST method called');
        out.println('parameters: ' + parameters(request));
        out.println('headers: ' + headers(request));
    }
 
    public void doDelete(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        out.println('Delete method called');
    }
 
    private String parameters(HttpServletRequest request) {
        StringBuilder builder = new StringBuilder();
        for (Enumeration e = request.getParameterNames(); e.hasMoreElements();) {
            String name = (String) e.nextElement();
            builder.append('|' + name + '->' + request.getParameter(name)+'\n');
        }
        return builder.toString();
    }
 
    private String headers(HttpServletRequest request) {
        StringBuilder builder = new StringBuilder();
        for (Enumeration e = request.getHeaderNames(); e.hasMoreElements();) {
            String name = (String) e.nextElement();
            builder.append('|' + name + '->' + request.getHeader(name)+'\n');
        }
        return builder.toString();
    }
}

And configure the servlet in the ‘web.xml’. By the way the generated ‘web.xml’ wasn’t able to be shown in my Netbeans version (v7.2.1). I got the message:

Web application version is unsupported. Upgrade web.xml to version 2.4 or newer or use previous version of NetBeans

To fixed this I modified the web.xml so it starts with the following declaration of namespaces:

<web-app xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xmlns='http://java.sun.com/xml/ns/javaee'
xmlns:web='http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd'
xsi:schemaLocation='http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd' id='WebApp_ID' version='2.5'>

Next add the servlet to the modified ‘web.xml’:

<?xml version='1.0' encoding='UTF-8'?>
...
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>TestRestServlet</servlet-name>
    <servlet-class>net.pascalalma.servlets.TestRestServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>TestRestServlet</servlet-name>
    <url-pattern>/TestRestServlet</url-pattern>
  </servlet-mapping>
...

Now everything is ready to test the servlet. As I said before I am going to use the Jetty plugin for this. To add the plugin to the project simply put the following in your ‘pom.xml’:

<plugins>
  <plugin>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>jetty-maven-plugin</artifactId>
    <configuration>
      <scanIntervalSeconds>10</scanIntervalSeconds>
      <contextPath>/</contextPath>
      <scanIntervalSeconds>10</scanIntervalSeconds>
      <stopKey>STOP</stopKey>
      <stopPort>8005</stopPort>
      <port>8080</port>
    </configuration>
  </plugin>
</plugins>

Now I can run the command ‘mvn jetty:run’ in my terminal to have the container running the servlet. The log should end with something like:

....
2013-02-19 09:54:53.044:INFO:oejs.AbstractConnector:Started SelectChannelConnector@0.0.0.0:8080
[INFO] Started Jetty Server
[INFO] Starting scanner at interval of 10 seconds.</code>

Now if you open a browser and go to the this url ‘http://localhost:8080/TestRestServlet?bla=true’ you will see the servlet in action and outputting to the browser:

GET method called
parameters:
|bla->true

headers:
|DNT->1
|Host->localhost:8080
|Accept->text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
|Accept-Charset->ISO-8859-1,utf-8;q=0.7,*;q=0.3
|Accept-Language->en-US,en;q=0.8
|User-Agent->Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_5) AppleWebKit/537.17 (KHTML, like Gecko) Chrome/24.0.1312.57 Safari/537.17
|Connection->keep-alive
|Cache-Control->max-age=0
|Accept-Encoding->gzip,deflate,sdch

One note: As you can see in the plugin configuration I have added a few extra parameters for my convenience. So will the container check every 10 seconds for changes in the servlet, so I don’t have to restart the Jetty container after each change of the servlet. To stop the container you can now enter the command ‘mvn jetty:stop -DstopPort=8005 -DstopKey=STOP’ in another terminal session. By the way, make sure you name the plugin ‘jetty-maven-plugin’ and not ‘maven-jetty-plugin’ because then you will be using an old version of the plugin which doesn’t pickup the configuration parameters (yes, very confusing and frustrating as I found out).

Reference: Using Maven Jetty plugin from our JCG partner Pascal Alma at the The Pragmatic Integrator blog.