maven-in-5-steps

First 5 Steps in Maven

• Defining what Maven does is very difficult.

• Every Day Developer does a lot of things

  • Manages Dependencies - Web Layer (Spring MVC), Data Layer (JPA - Hibernate) etc..
  • Build a jar or a war or an ear
  • Run the application locally - Tomcat or Jetty
  • Deploy to a T environment
  • Add new dependencies to a project
  • Run Unit Tests

• Maven helps us do all these and more...

  • Generate Projects
  • Create Eclipse Workspace

Getting Started

• Git Repository - https://github.com/in28minutes/getting-started-in-5-steps
• Pre-requisites - Java & Eclipse - https://www.youtube.com/playlist?list=PLBBog2r6uMCSmMVTW_QmDLyASBvovyAO3
• We will use embedded maven in Eclipse

Step 1 : Creating and importing a Maven Project

• We will create a Spring Boot project using http://start.spring.io
• We will import it into Eclipse as a Maven Project

Step 2 : Understanding Project Object Model - pom.xml

• Naming a project
• Declaring Dependencies

Step 3 : Maven Build Life Cycle

• run "mvn clean install"
• Build LifeCycle - Validate, Compile, Test, Package, Integration Test, Verify, Install, Deploy
• Convention over Configuration - Pre defined folder structure
  • Source Code
    • ${basedir}/src/main/java
    • ${basedir}/src/main/resources
  • Test Code
    • ${basedir}/src/test

Step 4 : How does Maven Work?

• Local Repository
• Maven repository
  • stores all the versions of all dependencies. JUnit 4.2,4.3,4.4
  • mvn install - copies the created jar to local maven repository - a temp folder on my machine where maven stores the files.

Step 5 : Important Maven Commands

• mvn --version
• mvn compile (compiles source files)
• mvn test-compile (compiles test files) - one thing to observe is this also compiles source files
• mvn clean - deletes target directory
• mvn test - run unit tests
• mvn package - creates the jar
• help:effective-settings
• help:effective-pom
• dependency:tree
• dependency:sources
• --debug

Complete Code Example

/pom.xml

<?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>com.in28minutes.learning.maven</groupId>
	<artifactId>maven-in-few-steps</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	
	<packaging>jar</packaging>

	<name>maven-in-few-steps</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.0.BUILD-SNAPSHOT</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

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

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
<!--

Remote Maven Repository
-> 
Local Maven Repository
  
 - Local Repository => Local System

 - Remote Maven repository => Central Repositories
   - stores all the versions of all dependencies. JUnit 4.2,4.3,4.4

 - mvn install vs mvn deploy 
   - copies the created jar to local maven repository - a temp folder on my machine where maven stores the files.
-->
	<repositories>
		<repository>
			<id>spring-snapshots</id>
			<name>Spring Snapshots</name>
			<url>https://repo.spring.io/snapshot</url>
			<snapshots>
				<enabled>true</enabled>
			</snapshots>
		</repository>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</repository>
	</repositories>

	<pluginRepositories>
		<pluginRepository>
			<id>spring-snapshots</id>
			<name>Spring Snapshots</name>
			<url>https://repo.spring.io/snapshot</url>
			<snapshots>
				<enabled>true</enabled>
			</snapshots>
		</pluginRepository>
		<pluginRepository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</pluginRepository>
	</pluginRepositories>


</project>

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/src/main/java/com/in28minutes/learning/maven/maveninfewsteps/MavenInFewStepsApplication.java

package com.in28minutes.learning.maven.maveninfewsteps;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MavenInFewStepsApplication {

	public static void main(String[] args) {
		SpringApplication.run(MavenInFewStepsApplication.class, args);
	}
}

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/src/main/resources/application.properties

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/src/test/java/com/in28minutes/learning/maven/maveninfewsteps/MavenInFewStepsApplicationTests.java

package com.in28minutes.learning.maven.maveninfewsteps;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class MavenInFewStepsApplicationTests {

	@Test
	public void contextLoads() {
	}

}

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