Overview

What is Maven? So I decided to investigate and use it. Personal notes.

What is Maven?

I read the following. http://d.hatena.ne.jp/keyword/Maven https://kengotoda.gitbooks.io/what-is-maven/content/preface.html

Build tool You can easily build and deploy projects, generate test reports, etc. without having to write build.xml by yourself like Apache Ant.

Something like PEAR in PHP.
Currently, it seems that there are up to Maven3, and the latest version seems to be Maven3.3.9.

I've never used Java, so I decided to use Maven to run it as a study of Java.

Prerequisites

centos7
java8

Installation procedure

$ wget http://ftp.jaist.ac.jp/pub/apache/maven/maven-3/3.3.9/binaries/apache-maven-3.3.9-bin.tar.gz

$ tar xvzf apache-maven-3.3.9-bin.tar.gz

$ mv apache-maven-3.3.9 /usr/local/

$ ln -s /usr/local/apache-maven-3.3.9/bin/mvn /usr/local/bin/mvn

$ mvn --version
Apache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-10T16:41:47+00:00)
Maven home: /usr/local/apache-maven-3.3.9
Java version: 1.8.0_111, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.111-1.b15.el7_2.x86_64/jre
Default locale: en_US, platform encoding: ANSI_X3.4-1968
OS name: "linux", version: "4.4.27-boot2docker", arch: "amd64", family: "unix"

Project creation

mvn archetype:generate -DinteractiveMode=false \
                         -DarchetypeGroupId=pl.org.miki \
                         -DarchetypeArtifactId=java8-quickstart-archetype \
                         -DgroupId=hello.world \
                         -DartifactId=helloworld \
                         -Dversion=1.0-SNAPSHOT \
                         -Dpackage=hello.world \
                         -Dpackaging=jar
$ tree helloworld/
helloworld/
|-- pom.xml
`-- src
    |-- main
    |   `-- java
    |       `-- hello
    |           `-- world
    `-- test
        `-- java
            `-- hello
                `-- world

9 directories, 1 file

Generated pom.xml

pom.xml is an important file with information about the project. For example, it contains information about building a project, information about dependent libraries, plugin settings, and so on.

reference http://www.techscore.com/tech/Java/ApacheJakarta/Maven/2-2/#maven-2-4

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>hello.world</groupId>
	<artifactId>helloworld</artifactId>
	<version>1.0-SNAPSHOT</version>
	<packaging>jar</packaging>


	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<java.version>1.8</java.version>
	</properties>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<source>${java.version}</source>
					<target>${java.version}</target>
				</configuration>
			</plugin>
		</plugins>
	</build>
	<dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.11</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
</project>

Place the source

$ pwd
/root/helloworld/src/main/java/hello/world

$ cat HelloWorld.java
package hello.world;

public class HelloWorld {
    public static void main(String[] args){
        System.out.println("Hello, world.");
    }
}

Source code build

Build creates target directory

$ cd helloworld
$ mvn compile
$ tree helloworld/
helloworld/
|-- pom.xml
|-- src
|   |-- main
|   |   `-- java
|   |       `-- hello
|   |           `-- world
|   |               `-- HelloWorld.java
|   `-- test
|       `-- java
|           `-- hello
|               `-- world
`-- target
    |-- classes
    |   `-- hello
    |       `-- world
    |           `-- HelloWorld.class
    |-- generated-sources
    |   `-- annotations
    `-- maven-status
        `-- maven-compiler-plugin
            `-- compile
                `-- default-compile
                    |-- createdFiles.lst
                    `-- inputFiles.lst

19 directories, 5 files

Source execution

$ java hello.world.HelloWorld

Fitted 1

When writing package ~~~ in Java source, It had to be matched with the package specified at the time of execution when Maven project was generated.

Fitted 2

It didn't work when I ran the generated source. As a result, the java execution location was not good.

In this case, the package was hello.world. The place to execute was as follows.

$ pwd
/root/helloworld/target/classes

$ java hello.world.HelloWorld
Hello, world.

Fitted 3

Although it is not the source given in this example By using try-with-resources in the source to build, There was a problem that I couldn't build it well. try-with-resources was implemented from Java7, but now it's Java8 I was wondering why it didn't work. .. ..

So, as a solution, I had to explicitly tell you to build with Java 8 when creating the project.

I referred to the following. http://qiita.com/mkamotsu/items/98c6d721a87a74f2b36f http://d.hatena.ne.jp/Kazuhira/20151010/1444479555

[JAVA] Try using Maven