Maven uses archetype plugins to create projects. To create a simple java application, we’ll use maven-archetype-quickstart plugin. In example below, we’ll create a maven-based java application project in C:\MVN folder.
Let’s open the command console, go to the C:\MVN directory and execute the subsequent mvn command.
C:\MVN>mvn archetype:generate
-DgroupId = com.companyname.bank
-DartifactId = consumerBanking
-DarchetypeArtifactId = maven-archetype-quickstart
-DinteractiveMode = false
Maven will start processing and will create the complete java application project structure.
[INFO] Scanning for projects…
[INFO] Searching repository for plugin with prefix: ‘archetype’.
[INFO] ——————————————————————-
[INFO] Building Maven Default Project
[INFO] task-segment: [archetype:generate] (aggregator-style)
[INFO] ——————————————————————-
[INFO] Preparing archetype:generate
[INFO] No goals needed for project – skipping
[INFO] [archetype:generate {execution: default-cli}]
[INFO] Generating project in Batch mode
[INFO] ——————————————————————-
[INFO] Using subsequent parameters for creating project
from Old (1.x) Archetype: maven-archetype-quickstart:1.0
[INFO] ——————————————————————-

[INFO] Parameter: groupId, Value: com.companyname.bank
[INFO] Parameter: packageName, Value: com.companyname.bank
[INFO] Parameter: package, Value: com.companyname.bank
[INFO] Parameter: artifactId, Value: consumerBanking
[INFO] Parameter: basedir, Value: C:\MVN
[INFO] Parameter: version, Value: 1.0-SNAPSHOT

[INFO] project created from Old (1.x) Archetype in dir: C:\MVN\consumerBanking
[INFO] ——————————————————————
[INFO] BUILD SUCCESSFUL
[INFO] ——————————————————————
[INFO] Total time: 14 seconds
[INFO] Finished at: Tue Jul 10 15:38:58 IST 2012
[INFO] Final Memory: 21M/124M
[INFO] ——————————————————————
Now go to C:/MVN directory. You’ll see a java application project created, named consumer Banking (as specified in artifactId). Maven uses a standard directory layout as shown below −

Using the above example, we can understand the subsequent key concepts −

Sr.No.	Folder Structure & Description
1	consumerBanking contains src folder and pom.xml
2	src/main/java contains java code files under the package structure (com/companyName/bank).
3	src/main/test contains test java code files under the package structure (com/companyName/bank).
4	src/main/resources it contains images/properties files (In above example, we need to create this structure manually).

If you observe, you’ll find that Maven also created a sample Java Source file and Java Test file. Open C:\MVN\consumerBanking\src\main\java\com\companyname\bank folder, you’ll see App.java.
package com.companyname.bank;

/**
* Hello world!
*
*/
public class App {
public static void main( String[] args ){
System.out.println( “Hello World!” );
}
}
Open C:\MVN\consumerBanking\src\test\java\com\companyname\bank folder to see AppTest.java.
package com.companyname.bank;

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
* Unit test for simple App.
*/
public class AppTest extends TestCase {
/**
* Create the test case
*
* @param testName name of the test case
*/
public AppTest( String testName ) {
super( testName );
}

/**
* @return the suite of tests being tested
*/
public static Test suite() {
return new TestSuite( AppTest.class );
}

/**
* Rigourous Test 🙂
*/
public void testApp() {
assertTrue( true );
}
}
Developers are required to place their files as mentioned in table above and Maven handles all the build related complexities.
In the next chapter, we’ll discuss how to build and test the project using maven Build and Test Project.

Maven – Build & Test Project

What we learnt in Project Creation chapter is how to create a Java application using Maven. Now we’ll see how to build and test the application.
Go to C:/MVN directory where you’ve created your java application. Open consumerBanking folder. You’ll see the POM.xml file with the subsequent contents.
<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.companyname.projectgroup</groupId>
<artifactId>project</artifactId>
<version>1.0</version>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
</dependency>
</dependencies>
</project>
Here you can see, Maven already added Junit as test framework. By default, Maven adds a source file App.java and a test file AppTest.java in its default directory structure, as discussed in the previous chapter.
Let’s open the command console, go the C:\MVN\consumerBanking directory and execute the subsequent mvn command.
C:\MVN\consumerBanking>mvn clean package
Maven will start building the project.
[INFO] Scanning for projects…
[INFO] ——————————————————————-
[INFO] Building consumerBanking
[INFO] task-segment: [clean, package]
[INFO] ——————————————————————-
[INFO] [clean:clean {execution: default-clean}]
[INFO] Deleting directory C:\MVN\consumerBanking\target
[INFO] [resources:resources {execution: default-resources}]

[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources,
i.e. build is platform dependent!

[INFO] skip non existing resourceDirectory C:\MVN\consumerBanking\src\main\resources
[INFO] [compiler:compile {execution: default-compile}]
[INFO] Compiling 1 source file to C:\MVN\consumerBanking\target\classes
[INFO] [resources:testResources {execution: default-testResources}]

[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources,
i.e. build is platform dependent!

[INFO] skip non existing resourceDirectory C:\MVN\consumerBanking\src\test\resources
[INFO] [compiler:testCompile {execution: default-testCompile}]
[INFO] Compiling 1 source file to C:\MVN\consumerBanking\target\test-classes
[INFO] [surefire:test {execution: default-test}]
[INFO] Surefire report directory: C:\MVN\consumerBanking\target\surefire-reports

—————————————————–
T E S T S
—————————————————–

Running com.companyname.bank.AppTest

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.027 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] [jar:jar {execution: default-jar}]
[INFO] Building jar: C:\MVN\consumerBanking\target\
consumerBanking-1.0-SNAPSHOT.jar

[INFO]———————————————–
[INFO] BUILD SUCCESSFUL
[INFO]———————————————–

[INFO] Total time: 2 seconds
[INFO] Finished at: Tue Jul 10 16:52:18 IST 2012
[INFO] Final Memory: 16M/89M
[INFO]———————————————–
You’ve built your project and created final jar file, subsequent are the key learning concepts −
• We give maven two goals, first to clean the target directory (clean) and then package the project build output as jar (package).
• Packaged jar is available in consumerBanking\target folder as consumerBanking-1.0-SNAPSHOT.jar.
• Test reports are available in consumerBanking\target\surefire-reports folder.
• Maven compiles the source code file(s) and then tests the source code file(s).
• Then Maven runs the test cases.
• Finally, Maven creates the package.
Now open the command console, go the C:\MVN\consumerBanking\target\classes directory and execute the subsequent java command.
>java com.companyname.bank.App
You’ll see the result as follows −
Hello World!

Adding Java Source Files

Let’s see how we can add additional Java files in our project. Open C:\MVN\consumerBanking\src\main\java\com\companyname\bank folder, create Util class in it as Util.java.
package com.companyname.bank;

public class Util {
public static void printMessage(String message){
System.out.println(message);
}
}
Update the App class to use Util class.
package com.companyname.bank;

/**
* Hello world!
*
*/

public class App {
public static void main( String[] args ){
Util.printMessage(“Hello World!”);
}
}
Now open the command console, go the C:\MVN\consumerBanking directory and execute the subsequent mvn command.
>mvn clean compile
After Maven build is successful, go to the C:\MVN\consumerBanking\target\classes directory and execute the subsequent java command.
>java -cp com.companyname.bank.App
You’ll see the result as follows −
Hello World!

Maven – External Dependencies

As you know, Maven does the dependency management using the concept of Repositories. But what happens if dependency is not available in any of remote repositories and central repository? Maven provides answer for such scenario using concept of External Dependency.
For example, let us do the subsequent changes to the project created in ‘Creating Java Project’ section.
• Add lib folder to the src folder.
• Copy any jar into the lib folder. We’ve used ldapjdk.jar, which is a helper library for LDAP operations.
Now our project structure should look like the subsequent −

Here you are having your own library, specific to the project, which is an usual case and it contains jars, which may not be available in any repository for maven to download from. If your code is using this library with Maven, then Maven build will fail as it cannot download or refer to this library during compilation phase.
To handle the situation, let’s add this external dependency to maven pom.xml using the subsequent way.
<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.companyname.bank</groupId>
<artifactId>consumerBanking</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>consumerBanking</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>ldapjdk</groupId>
<artifactId>ldapjdk</artifactId>
<scope>system</scope>
<version>1.0</version>
<systemPath>${basedir}\src\lib\ldapjdk.jar</systemPath>
</dependency>
</dependencies>

</project>
Look at the second dependency element under dependencies in the above example, which clears the subsequent key concepts about External Dependency.
• External dependencies (library jar location) can be configured in pom.xml in equivvalent way as other dependencies.
• Specify groupId equivvalent as the name of the library.
• Specify artifactId equivvalent as the name of the library.
• Specify scope as system.
• Specify system path relative to the project location.
Hope now you are clear about external dependencies and you’ll be able to specify external dependencies in your Maven project.
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