The Maven Cookbook

6.1.1. Task

You need to run a web application in a servlet container.

6.1.2. Action

Configure your web application's Maven project to inlcude the Maven Jetty plugin as shown in the following POM:

<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>
  <groupId>org.sonatype.mcookbook</groupId>
  <artifactId>sample-web</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>sample-web Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>sample-web</finalName>
    <plugins>
      <plugin>
        <groupId>org.mortbay.jetty</groupId>
        <artifactId>maven-jetty-plugin</artifactId>
        <version>6.1.22</version>
      </plugin>
    </plugins>
  </build>
</project>

To start the web application in Jetty, run the run goal from the Maven Jetty plugin by running mvn jetty:run.

$ mvn jetty:run
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building sample-web Maven Webapp
[INFO]    task-segment: [jetty:run]
[INFO] ------------------------------------------------------------------------
[INFO] Preparing jetty:run
[INFO] [resources:resources {execution: default-resources}]
[WARNING] Using platform encoding (MacRoman actually) to copy filtered 
resources, i.e. build is platform dependent!
[INFO] Copying 0 resource
[INFO] [compiler:compile {execution: default-compile}]
[INFO] Nothing to compile - all classes are up to date
[INFO] [resources:testResources {execution: default-testResources}]
[WARNING] Using platform encoding (MacRoman actually) to copy filtered 
resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory ~/maven-cookbook/
mcookbook-examples/web/sample-web/src/test/resources
[INFO] [compiler:testCompile {execution: default-testCompile}]
[INFO] No sources to compile
[INFO] [jetty:run {execution: default-cli}]
[INFO] Configuring Jetty for project: sample-web Maven Webapp
[INFO] Webapp source directory = ~/maven-cookbook/mcookbook-examples/web/
sample-web/src/main/webapp
[INFO] Reload Mechanic: automatic
[INFO] Classes = ~/maven-cookbook/mcookbook-examples/web/sample-web/
target/classes
2009-11-28 19:25:18.129:INFO::Logging to STDERR via org.mortbay.log.StdErrLog
[INFO] Context path = /sample-web
[INFO] Tmp directory =  determined at runtime
[INFO] Web defaults = org/mortbay/jetty/webapp/webdefault.xml
[INFO] Web overrides =  none
[INFO] web.xml file = ~/maven-cookbook/mcookbook-examples/web/sample-web/
src/main/webapp/WEB-INF/web.xml
[INFO] Webapp directory = ~/maven-cookbook/mcookbook-examples/web/sample-web
/src/main/webapp
[INFO] Starting jetty 6.1.22 ...
2009-11-28 19:25:18.231:INFO::jetty-6.1.22
2009-11-28 19:25:18.405:INFO::No Transaction manager found - if your webapp 
requires one, please configure one.
2009-11-28 19:25:18.800:INFO::Started SelectChannelConnector@0.0.0.0:8080
[INFO] Started Jetty Server

At this point, you can use a web browser to navigate to http://localhost:8080/sample-web/ to interact with the web application.

6.1.3. Detail

Consider a simple web application with a single index.jsp page that contains a form, and a single Servlet that calculates a number from the Fibonacci sequence.

Example 6.1. Simple Form Accepting an Index to Pass to the Fibonacci Servlet

<html>
<body>
<h2>Fibonacci Page</h2>
<form action="fib" method="GET">
  <p>Fetch Fibonacci Sequence Index:
  <input type="text" name="index" size="5"/></p>
  <input type="submit" value="Calculate"/>
</form>
</body>
</html>

The following class is the Servlet which calculates the Fibonacci sequence. It takes a single parameter index and simply prints of the number at the specified position of the Fibonacci sequence.

Example 6.2. Fibonacci Servlet which Calculates a Number from the Fibonacci Sequence

package org.sonatype.mcookbook;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FibonacciServlet extends HttpServlet {

  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
      throws ServletException, IOException {
    int index = Integer.parseInt(req.getParameter("index"));
    resp.getWriter().write( fib(index) + "" );
    resp.getWriter().flush();
    resp.getWriter().close();
  }

  public long fib(int n) {
    if (n <= 1) return n;
    else return fib(n-1) + fib(n-2);
  }
}

The following web.xml configures the FibonacciServlet to respond to the request path <context>/fib.

Example 6.3. Web Application Descriptor for sample-web

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>fibonacci</servlet-name>
    <servlet-class>org.sonatype.mcookbook.FibonacciServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>fibonacci</servlet-name>
    <url-pattern>/fib</url-pattern>
  </servlet-mapping>
</web-app>

After running mvn:jetty, you can load the initial form by going to http://localhost:8080/sample-web/index.jsp. Populating the form with an index and pressing calculate will load the Fibonacci servlet and print out the number at that position of the sequence.

Chapter 6. Web Development

Chapter 6. Web Development

6.1. Running a Web Application in a Servlet Container

6.1.1. Task

6.1.2. Action

6.1.3. Detail