Apache Maven 3 : Web Application - 2020

Continuing from Apache Maven 3 - Dependencies.

In this chapter, we'll create a new web application which provides us *.war file and additional dependencies.

While we're running mvn archetype:generate, we'll choose
764: remote -> org.codehaus.mojo.archetypes:webapp-j2ee14 (J2EE 1.4 web application archetype)
as our archetype.

k@laptop:~/java/apache-maven-3.2.5/bin/myapp$ mvn archetype:generate
...
Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): 525: 764
Choose org.codehaus.mojo.archetypes:webapp-j2ee14 version: 
1: 1.0
2: 1.0.1
3: 1.1
4: 1.2
5: 1.3
Choose a number: 5: 
Downloading: http://repo.maven.apache.org/maven2/org/codehaus/mojo/archetypes/webapp-j2ee14/1.3/webapp-j2ee14-1.3.jar
Downloaded: http://repo.maven.apache.org/maven2/org/codehaus/mojo/archetypes/webapp-j2ee14/1.3/webapp-j2ee14-1.3.jar (2 KB at 10.7 KB/sec)
Downloading: http://repo.maven.apache.org/maven2/org/codehaus/mojo/archetypes/webapp-j2ee14/1.3/webapp-j2ee14-1.3.pom
Downloaded: http://repo.maven.apache.org/maven2/org/codehaus/mojo/archetypes/webapp-j2ee14/1.3/webapp-j2ee14-1.3.pom (911 B at 9.1 KB/sec)
Define value for property 'groupId': : com.k.bogotobogo
Define value for property 'artifactId': : mywebapp
Define value for property 'version':  1.0-SNAPSHOT: : 
Define value for property 'package':  com.k.bogotobogo: : 
Confirm properties configuration:
groupId: com.k.bogotobogo
artifactId: mywebapp
version: 1.0-SNAPSHOT
package: com.k.bogotobogo
 Y: : 
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Archetype: webapp-j2ee14:1.3
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: com.k.bogotobogo
[INFO] Parameter: artifactId, Value: mywebapp
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: package, Value: com.k.bogotobogo
[INFO] Parameter: packageInPathFormat, Value: com/k/bogotobogo
[INFO] Parameter: package, Value: com.k.bogotobogo
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: groupId, Value: com.k.bogotobogo
[INFO] Parameter: artifactId, Value: mywebapp
[INFO] project created from Archetype in dir: /home/k/java/apache-maven-3.2.5/bin/myapp/mywebapp
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 59.347s
[INFO] Finished at: Sun Feb 01 14:07:12 PST 2015
[INFO] Final Memory: 18M/163M
[INFO] ------------------------------------------------------------------------

k@laptop:~/java/apache-maven-3.2.5/bin/myapp/mywebapp$ ls
pom.xml  src

Here is our new pom.xml which Maven has generated for us:

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.k.bogotobogo</groupId>
  <artifactId>mywebapp</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>mywebapp</name>
  <url>http://maven.apache.org</url>

  <dependencies>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.4</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.1</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.0.2</version>
        <configuration>
          <source>1.4</source>
          <target>1.4</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

Three things are worth mentioning:

1. We have war package instead of jar package since it's a web application.

   <packaging>war</packaging>
   

2. We have servlet and jsp dependencies.

       <dependency>
         <groupId>javax.servlet</groupId>
         <artifactId>servlet-api</artifactId>
         <version>2.4</version>
         <scope>provided</scope>
       </dependency>
       <dependency>
         <groupId>javax.servlet.jsp</groupId>
         <artifactId>jsp-api</artifactId>
         <version>2.1</version>
         <scope>provided</scope>
       </dependency>
   

3. The compiler in Maven is actually a plugin. We set the behavior, especially, the configuration:

         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-compiler-plugin</artifactId>
           <version>2.0.2</version>
           <configuration>
             <source>1.4</source>
             <target>1.4</target>
           </configuration>
         </plugin>
   

When we compile it, Maven will download all packages that our project is dependent on:

k@laptop:~/java/apache-maven-3.2.5/bin/myapp/mywebapp$ mvn compile
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building mywebapp 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
Downloading: http://repo.maven.apache.org/maven2/javax/servlet/servlet-api/2.4/servlet-api-2.4.pom
Downloaded: http://repo.maven.apache.org/maven2/javax/servlet/servlet-api/2.4/servlet-api-2.4.pom (156 B at 0.2 KB/sec)
Downloading: http://repo.maven.apache.org/maven2/javax/servlet/servlet-api/2.4/servlet-api-2.4.jar
Downloaded: http://repo.maven.apache.org/maven2/javax/servlet/servlet-api/2.4/servlet-api-2.4.jar (96 KB at 165.9 KB/sec)
[INFO] 
[INFO] --- maven-resources-plugin:2.3:resources (default-resources) @ mywebapp ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory /home/k/java/apache-maven-3.2.5/bin/myapp/mywebapp/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:2.0.2:compile (default-compile) @ mywebapp ---
[INFO] Nothing to compile - all classes are up to date
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 6.477s
[INFO] Finished at: Sun Feb 01 15:15:00 PST 2015
[INFO] Final Memory: 11M/97M
[INFO] ------------------------------------------------------------------------
k@laptop:~/java/apache-maven-3.2.5/bin/myapp/mywebapp$ 

mvn package:

k@laptop:~/java/apache-maven-3.2.5/bin/myapp/mywebapp$ mvn package
...
[INFO] 
[INFO] --- maven-war-plugin:2.1.1:war (default-war) @ mywebapp ---
[INFO] Packaging webapp
[INFO] Assembling webapp [mywebapp] in [/home/k/java/apache-maven-3.2.5/bin/myapp/mywebapp/target/mywebapp-1.0-SNAPSHOT]
[INFO] Processing war project
[INFO] Copying webapp resources [/home/k/java/apache-maven-3.2.5/bin/myapp/mywebapp/src/main/webapp]
[INFO] Webapp assembled in [98 msecs]
[INFO] Building war: /home/k/java/apache-maven-3.2.5/bin/myapp/mywebapp/target/mywebapp-1.0-SNAPSHOT.war
[INFO] WEB-INF/web.xml already added, skipping
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 10.686s
[INFO] Finished at: Sun Feb 01 15:16:40 PST 2015
[INFO] Final Memory: 12M/161M
[INFO] ------------------------------------------------------------------------

Let's look at what's been generated so far:

1. We see our package file mywebapp-1.0-SNAPSHOT.war in target folder.
2. When we look into the src directory, we have nothing under src/main/java but we have index.jsp under the src/main/webapp folder:

   <%@page contentType="text/html" pageEncoding="UTF-8"%>
   <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
      "http://www.w3.org/TR/html4/loose.dtd">
   
   <html>
       <head>
           <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
           <title>JSP Page</title>
       </head>
       <body>
           <h1>Hello World!</h1>
       </body>
   </html>
   

   The web.xml should look like this:

   <?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">
       <display-name>mywebapp</display-name>
       <session-config>
           <session-timeout>
               30
           </session-timeout>
       </session-config>
       <welcome-file-list>
           <welcome-file>index.jsp</welcome-file>
           </welcome-file-list>
       </web-app>