Embedded jetty server with web app

Recently, I come across a situation where both maven-jetty plugin & embedded jetty server need to packed along with web-application. I have already written a blog on incorporating maven-jetty plugin in the web app here, hence will not be discussing here again. I will describe here about package of embedded jetty server with in web application below.

Firstly, why do we require to include embedded jetty?
1. Easy deployment, java -jar <web-app>.jar, once you build the artifact, it's ready for deployment without any hassle configurations/deployment procedures, etc
2. No requirement of application server.


Let's go through the following steps to include jetty server within web app.

1. Create a JettyServer class


package com.sateesh.application.server;

import org.eclipse.jetty.server.Connector;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.ServerConnector;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.servlet.ServletHolder;
import org.eclipse.jetty.util.thread.QueuedThreadPool;
import org.eclipse.jetty.webapp.WebAppContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.DispatcherServlet;

import java.io.IOException;


public class JettyServer {

    private static final Logger logger = LoggerFactory.getLogger(JettyServer.class);
    private final String WEB_APP_DIR = "src/main/webapp";
    private final String WEB_XML_PATH = "src/main/webapp/WEB-INF/web.xml";
    private static final String MVC_SERVLET_NAME = "dispatcher";
    private static final String JSP_SERVLET_NAME = "jspServlet";
    private static final String DEFAULT_PORT = "8080";
    private static final String DEFAULT_CONTEXT_PATH = "/";



    public static void main(String[] args) throws Exception{
        JettyServer jettyServer = new JettyServer();
        jettyServer.start();
    }

    private JettyServer() {
      // none can instantiate this class
    }

    private void start() throws Exception{
        try {
            QueuedThreadPool threadPool = new QueuedThreadPool(512);

            final Server server = new Server(threadPool);
            server.setStopAtShutdown(true);
            server.setStopTimeout(5000);

            ServerConnector connector = new ServerConnector(server);
            connector.setPort(getPort());
            connector.setIdleTimeout(30000);
            server.setConnectors(new Connector[]{connector});
            server.setHandler(getServletContextHandler());

            server.start();
            server.join();
            logger.info("Embedded Jetty Server is started!");
        } catch (Exception e) {
            logger.error("Exception occurred while starting the jetty server ", e);
        }
    }

    private WebAppContext getServletContextHandler() throws IOException {
        final WebAppContext contextHandler = new WebAppContext();
        contextHandler.setContextPath(getContextPath());
        contextHandler.setWar(WEB_APP_DIR);
        contextHandler.setDefaultsDescriptor(WEB_XML_PATH);
        ServletHolder jspServletHolder = new ServletHolder("jspServlet", new org.apache.jasper.servlet.JspServlet());
        // jsp servelet is required to parse the jsp passed by the spring-mvc  
        contextHandler.addServlet(jspServletHolder, "*.jsp");
        return contextHandler;
    }

 
  /**
  * Consider default port as "8080" until unless not passed using java args
  **/  private int getPort() {
        Integer port = Integer.parseInt(System.getProperty("jetty.port"));

        if (port == null || port == 0) {
            port = Integer.parseInt(DEFAULT_PORT);
        }

        return port;
    }

    
  /**
  * Consider default context path as "/" until unless not passed using java args
  **/
  private String getContextPath() {
        String contextPath = System.getProperty("jetty.contextPath");

        if (contextPath == null ||  contextPath.equals("")) {
            contextPath = DEFAULT_CONTEXT_PATH;
        }

        return contextPath;
    }

}


2. Contents of web.xml (default descriptor executed by JettyServer).

<?xml version="1.0" encoding="UTF-8"?>
<!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 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns="http://java.sun.com/xml/ns/javaee"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
        id="YourWebAppID"
        version="2.5">

    <display-name>Web App Server</display-name>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            classpath:META-INF/spring/application-context.xml
        </param-value>
    </context-param>

    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:dispatcher-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/api/*</url-pattern>
    </servlet-mapping>

</web-app>


3. Contents of application-context.xml & dispatcher-servlet.xml files

application-context.xml --- is spring descriptor file. 
dispatcher-servlet.xml --- is servlet dispatcher file, which will scan @Controller annotated packages.


4. Package structure of the project

   --- src
       --- main
           --- java 
               --- com.sateesh.application.server
           --- resources
               --- META-INF
                   --- spring
                       --- application-context.xml
               --- dispatcher-servlet.xml
               --- logback.xml
           --- webapp
               --- views
                   ---  ***.jsp
               --- web.xml


5. below plugin needs to be added in pom.xml

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.3</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <filters>
                                <filter>
                                    <artifact>*:*</artifact>
                                    <excludes>
                                        <exclude>META-INF/*.SF</exclude>
                                        <exclude>META-INF/*.DSA</exclude>
                                        <exclude>META-INF/*.RSA</exclude>
                                    </excludes>
                                </filter>
                            </filters>
                            <createDependencyReducedPom>true</createDependencyReducedPom>
                            <transformers>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>com.sateesh.application.server.JettyServer</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

6. add below dependencies in pom.xml

    <properties>
        <jetty.server.scope>compile</jetty.server.scope>
        <jetty.version>9.1.2.v20140210</jetty.version>
    </properties>

        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-server</artifactId>
            <version>${jetty.version}</version>
            <scope>${jetty.server.scope}</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-webapp</artifactId>
            <version>${jetty.version}</version>
            <scope>${jetty.server.scope}</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-servlet</artifactId>
            <version>${jetty.version}</version>
            <scope>${jetty.server.scope}</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-jsp</artifactId>
            <version>${jetty.version}</version>
            <scope>${jetty.server.scope}</scope>
        </dependency>

7. You are almost there.. now run the web application now.

build the project (default package is jar in maven):
mvn clean package

run the webapp:
java -jar target/webapp.jar


PS: we can also create embedded jetty server with in web-app without web.xml file also.