Try using Maven

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