Maven Final Notes.txt

-> Java is a programming language

-> Java language developed by sun microsystem company

-> Oracle company acquired Sun Microsystem 

-> Java is under license of Oracle company

-> Java is a high level programming language

-> Java is simple programming language

-> Java program files will have .java as extension

	Ex: Demo.java, Hello.java, Driver.java, Calculator.java etc..

-> We can't execute .java files directly

-> Java Programs should be converted into Machine understandable format to execute

-> Java Programs (.java file) contains source code

-> We need to compile java source code into byte code using java compiler (javac)

			Ex: javac Demo.java

-> When we compile java code it will create .class file

-> We need to execute .class file to run the java program

			Ex: java Demo

-> When we run java program using java command, JVM will start and it will execute java program

			Note: JVM stands for Java Virtual Machine

-> JVM will convert byte code into machine understandable code

-> Java project contains several java programs (.java files)

-> We need to compile project source code into byte code

-> When we compile project source code we will get .class files

-> To deploy java project, we will package all .class files as JAR or WAR file

			JAR : Java Archieve
			WAR : Web Archieve

-> Standalone java projects will be packaged as JAR file

-> Web Applications will be packaged as WAR file

Note: The software which is specific to only one computer i.e called StandAlone application



Maven
+++++

-> Maven is a free and open source software given by Apache Organization

-> Maven s/w is developed using Java programming language

-> Maven is used to perform Build Automation for java projects

-> Maven is called as Java Build Tool


What we can do using maven
++++++++++++++++++++++++++
1) We can create initial project folder structure using maven

2) We can download "project dependencies" using maven
    (ex : springboot, hibernate, kafka, redis, email, log4j, junit, security...)

-> To develop one java project we will use several frameworks like spring, hibernate etc along with Java

-> We need to download those frameworks and we should  add to our java project

-> These frameworks we are using in our project are called as our project dependencies

-> Instead of we are downloading dependencies, we can tell to maven s/w to download dependencies

Note: Required dependencies we will add in "pom.xml" file then maven s/w will download them

-> pom stands for project object model

-> When we create maven project then pom.xml file will be created automatically

-> pom.xml will act as input file for maven software

3) We can compile project source code using maven

4) We can package java project as jar or war file using maven


Maven Installation
++++++++++++++++++

1) Download and install Java software

-> When we install java we will below 2 things

		a) JDK (Java Development Kit) 

		b) JRE (Java Runtime Environment)

-> JDK contains set of tools to develop java programs and compile the program

-> JRE contains platform/environment which is used to run java programs

Link To Download Java : https://www.oracle.com/in/java/technologies/javase/javase8-archive-downloads.html

2) Set JAVA_HOME in Environment Variables (System Env Variables) 

			User Environment Variables: Specific to particular account which logged in our PC

			System Envrionment Variables : For All Accounts it will be applicable

Note: Y Environment variables means to tell to Operating System my java is available in so and so location iam going to set JAVA_HOME in Environment Variable
	JAVA_HOME we are configuring upto jdk
	(Y environment variable means environment variables will be used by OperatingSystem to find the locations of our softwares)

Note: Environment Variables will be used by operating system

			JAVA_HOME = C:\Program Files\Java\jdk1.8.0_202

3) Set Path for JAVA (Go to System Env Variables -> Env Variables -> System Variables -> Select Path and Click on Edit then add JDK path)
	

			Path = C:\Program Files\Java\jdk1.8.0_202\bin

4) Verify Java installation by executing below command in "Command Promt"

			> java -version

Note: It should dipslay java version which we have installed

Note : Y Iam Installing Java means Maven software is developed by using java language, if u want to run the Maven then u need the java so thats y we install java first

5) Download Maven software from Apache website

		Link To download Maven : https://maven.apache.org/download.cgi
		File Name : 	apache-maven-3.8.5-bin.zip (Binary Archive)

6) Extract Maven Zip file -> Copy extracted maven folder and paste it in "C" drive

7) Set MAVEN_HOME in System Environment Variables

		MAVEN_HOME = C:\apache-maven-3.8.5
Note: MAVEN_HOME is going to tell where is the maven software in the system

8) Set Path for Maven in System Environment Variables

		Path : C:\apache-maven-3.8.5\bin

9) Open Command Prompt and verify Maven Installaton using below command

		> mvn -version

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Maven Terminology
++++++++++++++++++

archetype
groupId
artifactId
packaging


-> Archteype represents what type of project we want to create
	
		=> maven-archetype-quickstart : It represents java standalone application

		=> maven-archetype-webapp : It represents java web application

Note: Maven providing 1500+ archetypes in those archetypes it represents what type of project u want to create 
      if ur requirement is to create java standalone project then u need to select as maven-archetype-quick
      if ur requirement is to crate web application project then u have to select as maven-archetype-webapp

-> groupId represents company name or project name

-> artifactId represents project name or project module name

-> packaging represents how we want to package our java application (jar or war)



Creating standalone application using maven
+++++++++++++++++++++++++++++++++++++++++++++

1) Create one folder for maven practise 

2) Open Command prompt from that folder

3) Execute below command to create maven project


>> mvn archetype:generate -DgroupId=in.ashokit -DartifactId=01-Maven-App -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

4) Once project created verify project folder structure

			01-Maven-App
				- src						src/main/java => it contains application source code( .java files )

					- main					src/test/java => it contains unit test  source code(Junit code)(.java files)
						-java

					- test
						-java

				- pom.xml


		src/main/java : Application source code (.java files)

		src/test/java : Application Unit Test code (.java files)

		pom.xml : Project Object Model (Maven configuration file)

5) We can add dependencies in pom.xml file

6) We can find maven dependencies in www.mvnrepository.com website

7) Add below dependency in pom.xml file

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>5.2.22.RELEASE</version>
</dependency>


How maven will download dependencies
++++++++++++++++++++++++++++++++++++
-> Maven will download dependencies using repository

-> In Maven we have 3 types of repositories

	1) Central Repository

	2) Remote Repository

	3) Local Repository

-> central repository is maintaining by apache organization

-> every company will maintain their own remote repository

-> Local repository will be created in our system (Location : C://users/<uname>/.m2)  if u goo to that location u can see maven local repository i.e .me is local repository


-> When we add dependency in pom.xml, maven will search for that dependency in local repository. If it is available it will add to project build path.

-> If dependency not available in local repository then maven will connect to Central Repository or Remote Repository based on our configuration.

Note: By default maven will connect with central repository. If we want to use remote reposiotry then we need to configure remote repository details.


Note: Every software company will maintain their own remote repository (Ex: JFrog)



Configuring Remote Repository
+++++++++++++++++++++++++++++
<repositories>
        <repository>
            <id>id</id>
            <url>jfrong-repo-url/</url>
        </repository>     
</repositories>



Maven Goals
++++++++++++

-> To perform project build activities maven prorvided several goals for us


clean
compile
test
package
install

-> clean goal is used to delete target folder

-> compile goal is used to compile project source code. Compiled code will be stored in target folder

						compile
				.java ------------> .class

-> test goal is used to execute unit test code of our application (junit code)

-> package goal is used to generate jar or war file for our application based on packaging type available in pom.xml file.

Note: jar or war file will be created in target folder.

-> install goal is used to install our project as a dependency in maven local repository.

Note: Every maven goal is associated with maven plugin. When we execute maven goal then respective maven plugin will execute to perform the operation.


Syntax : mvn  <goal-name>

Note: We need to execute maven goals from project folder

creating web application using maven
+++++++++++++++++++++++++++++++++++++++
>> mvn archetype:generate -DarchetypeArtifactId=maven-archetype-webapp -DgroupId=in.ashokit -DartifactId=01-maven-web-app -DinteractiveMode=false

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What is Java ?
	A: java is programming language which i used to develop the applications

What is source code ?

	A: whenever we write the java program that file will have a .java extension that us called as source code
	   java source code cannot understand by our computers so we need to convert java source code into computers understandable  format for that we are going to do compilation
	   java compiler is available to compile the java program that java programs will compiled into Byte code

What is Byte code ?
	A: Byte code means .class file, Byte code also cannot understand by machine
	   
What is machine understandable code ?
	A: The Byte code will be converted to machine understandable code by using JVM 

Java Program Execution Process

What is JDK
	A: JDK means Java Development Kit which is used to develop the java programs

What is JRE
	A: JRE means Java Runtime Environment which is used run the Java program

What is JVM

What is Project Dependency? (Ex : hibernate, spring, kafka, redis etc)

What is Maven
	A: Maven is Build Tool which is Given by Apache organisation, which is used to automate the build process

What are the advantages of Maven
	A: Maven can create the Folder structure
	   Maven can compile the source code
	   Maven can execute the unit test case
	   Maven can package the project

Java Installation
Setting JAVA_HOME & JDK PATH
Maven Installation
setting MAVEN_HOME & Maven Path

Maven Terminology
		- archetype
		- groupId
		- artifactId
		- version
		- packaging

Pom.xml

Adding dependency in pom.xml

Java Standalone project creation using Maven

Maven Project Folder Structure

Java Web application creating using Maven

Maven Repositories
	 - Local Repository
	 - Central Repository
	 - Remote Repository

Maven Goals 
	- clean
	- compile
	- test
	- package
	- install

Maven Plugins

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