Maven by default creates a JAR package. But we can build package in any other format easily through Maven. This blog explains how to generate a WAR package, customizing the MANIFEST and web.xml files within it, using simple HelloWorld example.
Project structure<proj-home>
pom.xml src
main
java
App.java target
simple-1.1-SNAPSHOT.jar
First we create a Java file which prints Hello World. Maven projects expects Java source files under src/main/java directory. Hence lets create our Hellow World program App.java under it.
The content of App.java is
public class App{ public static void main (String args[]) { System.out.println("Hello World"); }}
Create a simple pom.xml file to compile, package (generate JAR file by default)
Create the below pom.xml file under <proj-home>
<project> <modelVersion>4.0.0</modelVersion> <groupId>com.rsa.siddesh.simple</groupId> <artifactId>simple</artifactId> <packaging>jar</packaging> <version>1.1-SNAPSHOT</version> <name>simple</name> </project>Compile the Simple project Run the command
mvn package
On it's successful completion it will create simple-1.1-SNAPSHOT.jar file under <proj-home>/target directory.
Creating WAR package As explained above, maven created by default the JAR package. Now its time create a WAR package for the same project. A web application (war) needs to have some additional files like web.xml, jsp files, servlet, images, etc. The below directory structure depicts the needy files for one of the sample web application. I took this sample application code from Spring Source site
http://static.springsource.com/projects/tc-server/6.0/getstart/tgsdevtut.htmlThis site explains building web app using Ant, but I migrated the same code to build with Maven.
<proj-home>
pom.xml src
main
java
examples
Hello.java resources
images
springsource.png webapp
images
springsource.png jsp
hello.jsp WEB-INF
web.xml target simple-1.1-SNAPSHOT.war Now lets look at the code for all source files mentioned above.
pom.xml<project> <modelVersion>4.0.0</modelVersion> <groupId>com.rsa.siddesh.simple</groupId> <artifactId>simple</artifactId> <packaging>war</packaging> <version>1.1-SNAPSHOT</version> <name>simple</name> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> </dependency> </dependencies></project>Hello.java - It's a Java servlet file.package examples;
import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;
/** * Simple Hello servlet. */
public final class Hello extends HttpServlet {
/** * Respond to a GET request for the content produced by * this servlet. * * @param request The servlet request we are processing * @param response The servlet response we are producing * * @exception IOException if an input/output error occurs * @exception ServletException if a servlet error occurs */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.setContentType("text/html"); PrintWriter writer = response.getWriter(); writer.println("<html>"); writer.println("<head>"); writer.println("<title>Sample Application Servlet Page</title>"); writer.println("</head>"); writer.println("<body bgcolor=white>");
writer.println("<table border=\"0\" cellpadding=\"10\">"); writer.println("<tr>"); writer.println("<td>"); writer.println("<img src=\"images/springsource.png\">"); writer.println("</td>"); writer.println("<td>"); writer.println("<h1>Sample Application Servlet</h1>"); writer.println("</td>"); writer.println("</tr>"); writer.println("</table>");
writer.println("This is the output of a servlet that is part of"); writer.println("the Hello, World application.");
writer.println("</body>"); writer.println("</html>"); }}
springsource.png - Download this image from springsource web link given abovehello.jsp<html> <head> <title>Sample Application JSP Page</title> </head>
<body bgcolor=white>
<table border="0" cellpadding="10"> <tr> <td align=center> <img src="../images/springsource.png"> </td> <td> <h1>Sample Application JSP Page</h1> </td> </tr> </table>
<br /> <p>This is the output of a JSP page that is part of the HelloWorld application.</p>
<%= new String("Hello!") %>
</body></html>
web.xml<?xml version="1.0" encoding="ISO-8859-1" ?>
<web-app 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" version="2.4">
<display-name>HelloWorld Application</display-name> <description> This is a simple web application with a source code organization based on the recommendations of the Application Developer's Guide. </description>
<servlet> <servlet-name>HelloServlet</servlet-name> <servlet-class>examples.Hello</servlet-class> </servlet>
<servlet-mapping> <servlet-name>HelloServlet</servlet-name> <url-pattern>/hello</url-pattern> </servlet-mapping>
</web-app>
Run the command
mvn packageIt will create a war file target/simple-1.1-SNAPSHOT.war, which can be deployed on web server like Apache tomcat. A war file contains MANIFEST files which is created by Maven and also the web.xml files.
Customizing it to add our own values is described in next blog