In this article, we will create a very simple java project and build it with Maven. This guide will help you to understand the basics of Java coding and how to build this code with Maven.
Create a Github Repository:
I hope you have Github repository, if not I recommend you to create one. To download and use it with other projects I will add this code to my Github repository.
Create a repository called “sample-java-project” on Github.
Clone the empty repository to your terminal.
$ git clone https://github.com/techiescorner/sample-maven-project.git Cloning into 'sample-maven-project'... warning: You appear to have cloned an empty repository.
Git installation and configuration are not a scope of this tutorial so skipped that.
Create a folder structure:
Here I am using the nix (Amazon Linux ) system to do the coding.
Create a directory structure as follows inside the repository folder
$ cd sample-maven-project/ . └── src └── main └── java └── first
Execute the below command to create the directory.
mkdir -p src/main/java/first
Next, create two classes inside the “first” folder. I have created FirstCode.java and Welcome.java you can create any java classes.
Open the FirstCode.java file with your favorite editor and add the below code.
package hello;
public class FirstCode {
public static void main(String[] args) {
Welcome greeter = new Greeter();
System.out.println(greeter.sayHello());
}
}Next, Open the Welcome.java file and add the below code.
package hello; public class Welcome { public String sayHello() { return "Welcome to the first Java code !!!!"; } }
Now the code is ready, next, we have to build it with Maven. I have already installed Maven in the system. If you haven’t installed please refer below link.
Create a Maven pom.xml file
Once the maven is installed we have to create a pom.xml file. POM.xml file is a Maven project definition. This file contains the details like Project name, version, and dependencies. Create this file near the “src” folder.
create a file named pom.xml file and add the below codes.
<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>www.techiescorner.in</groupId>
<artifactId>TC-Maven</artifactId>
<packaging>jar</packaging>
<version>0.1.0</version>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.1</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>hello.FirstCode</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project> The above pom.xml file is the simplest one for a project and it contains the following details.
<modelVersion> : POM model version.
<groupId> : Organization or Group name which the project belongs to.
<artificatId> : Name for the project’s library artifact (for example, the name of its JAR or WAR file)
<version> : Version of the project
<packaging> : How the project output should be packaged. Defaults to “jar” for JAR file packaging. Use “war” for WAR file packaging.
<mainClass> : Add your mail class name here.
Build the java code:
We have developed our code and now it is ready to build using Maven. To compile the code execute below command from where pom.xml file is present.
[root@jenkins ~]# mvn compile [INFO] Scanning for projects... [INFO] [INFO] -------------------< www.techiescorner.in:TC-maven >-------------------- [INFO] Building TC-maven 0.1.0 [INFO] --------------------------------[ jar ]--------------------------------- [INFO] [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ TC-maven --- [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory /root/src/main/resources [INFO] [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ TC-maven --- [INFO] Changes detected - recompiling the module! [WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent! [INFO] Compiling 2 source files to /root/target/classes [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS
If you are executing it the first time it may take a few minutes to complete the compile.
The compiled .class files will be in the target/classes directory.
Next, we have to package the compiled code. The package command will compile your Java code, run any tests, and finish by packaging the code up in a JAR file within the target directory.
Execute the below command to package the compiled code from the same folder.
# ls pom.xml src target [root@jenkins ~]# mvn package [INFO] Scanning for projects... [INFO] [INFO] -------------------< www.techiescorner.in:TC-maven >-------------------- [INFO] Building TC-maven 0.1.0 [INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ TC-maven [INFO] No sources to compile [INFO] [INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ TC-maven --- [INFO] No tests to run. [INFO] [INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ TC-maven --- [INFO] Building jar: /root/target/TC-maven-0.1.0.jar [INFO] [INFO] --- maven-shade-plugin:2.1:shade (default) @ TC-maven --- [INFO] Replacing original artifact with shaded artifact. [INFO] Replacing /root/target/TC-maven-0.1.0.jar with /root/target/TC-maven-0.1.0-shaded.jar [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS
Once the build is completed you will get a success message at the end.
The name of the output JAR file will be based on the project’s <artifactId> and <version> and present in the target folder.
]# ls classes generated-sources maven-archiver maven-status TC-maven-0.1.0.jar
To get the output of the code or to open the JAR execute below command from the target folder.
# java -jar TC-maven-0.1.0.jar Welcome to the first Java code !!!!
We have successfully built our Java code.
Push the code to Github:
Execute the below codes from the sample-maven-project directory to push the code to the Github repository.
[root@jenkins sample-maven-project]# git init Initialized empty Git repository in /root/sample-maven-project/.git/ [root@jenkins sample-maven-project]# ls pom.xml src target [root@jenkins sample-maven-project]# git add . [root@jenkins sample-maven-project]# git commit -m "sample java code" [master (root-commit) c2997f4] sample java code 9 files changed, 64 insertions(+) create mode 100644 pom.xml create mode 100644 src/main/java/first/FirstCode.java create mode 100644 src/main/java/first/Welcome.java create mode 100644 target/TC-maven-0.1.0.jar create mode 100644 target/classes/hello/FirstCode.class create mode 100644 target/classes/hello/Welcome.class create mode 100644 target/maven-archiver/pom.properties create mode 100644 target/maven-status/maven-compiler-plugin/compile/default-compile/createdFiles.lst create mode 100644 target/maven-status/maven-compiler-plugin/compile/default-compile/inputFiles.lst # git remote add origin https://github.com/techiescorner/sample-maven-project.git # git remote -v origin https://github.com/techiescorner/sample-maven-project.git (fetch) origin https://github.com/techiescorner/sample-maven-project.git (push) # git push -u origin master Username for 'https://github.com': techiescorner Password for 'https://techiescorner@github.com': Counting objects: 23, done. Compressing objects: 100% (14/14), done. Writing objects: 100% (23/23), 4.47 KiB | 2.23 MiB/s, done. Total 23 (delta 0), reused 0 (delta 0) To https://github.com/techiescorner/sample-maven-project.git * [new branch] master -> master Branch master set up to track remote branch master from origin.
To download the code to your server or local machine execute the below code.
git clone https://github.com/techiescorner/sample-maven-project.git
