Embedded Server – Tomcat 7

<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>com.heroku.sample</groupId>
<artifactId>embeddedTomcatSample</artifactId>
<version>1.0-SNAPSHOT</version>
<name>embeddedTomcatSample Maven Webapp</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-core</artifactId>
<version>7.0.22</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-logging-juli</artifactId>
<version>7.0.22</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
<version>7.0.22</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jasper</artifactId>
<version>7.0.22</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jasper-el</artifactId>
<version>7.0.22</version>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-jsp-api</artifactId>
<version>7.0.22</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
</dependencies>
<build>
<finalName>embeddedTomcatSample</finalName>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>appassembler-maven-plugin</artifactId>
<version>1.1.1</version>
<configuration>
<assembleDirectory>target</assembleDirectory>
<programs>
<program>
<mainClass>com.ego.apps.Launch</mainClass>
<name>webapp</name>
</program>
</programs>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>assemble</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

Note – the dependencies section list out the JARs needed for embedded tomcat.

Now we need to tell maven to download these dependencies – so that we can continue with our application. Navigate to the SampleProject folder and issue command

mvn install

This would install all the dependencies required.

Now, go ahead and create a servlet. We created following

package com.ego.apps.servlets;

import java.io.IOException;

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

import org.apache.log4j.Logger;

public class TestServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
{
try
    {
    response.getOutputStream().print("Hello World!");
    }
catch (IOException e)
    {
    }
}
}

And edit the web.xml in WEB-INF as

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>

<servlet>
<servlet-name>Test</servlet-name>
<servlet-class>com.ego.apps.servlets.TestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Test</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>

</web-app>

This completes our web application setup by issuing final command

mvn clean install

Embedding tomcat server

package com.ego.apps;

import java.io.File;

import org.apache.catalina.startup.Tomcat;
import org.apache.log4j.Logger;

public class Launch {
public static void main(String[] args) throws Exception {
Logger logger = Logger.getLogger(Launch.class);
String webappDirLocation = "src/main/webapp/";
Tomcat tomcat = new Tomcat();

// Look for that variable and default to 8080 if it isn't there.
String webPort = System.getenv("PORT");
if (webPort == null || webPort.isEmpty()) {
webPort = "8080";
}
logger.info("Application port set to: " + webPort);
tomcat.setPort(Integer.valueOf(webPort));

tomcat.addWebapp("/", new File(webappDirLocation).getAbsolutePath());
logger.info("configuring app with basedir: "
+ new File("./" + webappDirLocation).getAbsolutePath());

tomcat.start();
logger.info("Application started.");
tomcat.getServer().await();
}
}

Tomcat tomcat = new Tomcat();</pre>
tomcat.setPort(Integer.valueOf(webPort));