Maven Basics

Pain point of the original project (process control problem)

Software testing, document generation, packaging and release - it's best to be automated (one click release)
The project relies on a large number of third-party jar packages, which is complex and difficult to manage - POM xml
jar is a different manufacturer, and there are too many download sources - warehouse
Module dependency

summary

Maven is a software project management and comprehension tool
Software engineering management tools
maven official website

Installation + configuration

download
Unzip the compressed package you just downloaded
Configure environment variables

Architecture project -- Take Hello as an example

Convention is more important than configuration -- it has its own directory structure

1. Default configuration

Manually create directory structure

pom.xml Content:
	<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>
	  <!-- coordinate : Location of this item in the warehouse -->
	  <groupId>com.yc.test</groupId>
	  <artifactId>my-app</artifactId>
	  <version>1.0-SNAPSHOT</version>
	 
	  <name>my-app</name>
	</project>

test

2. Test various goal s

Different commands will automatically download different plug-ins. maven runs in the form of plug-ins
mvn clean: clear the output directory, that is, delete the target directory
mvn compile: compile, that is, generate the target directory
mvn test: Test
mvn package: package it into a jar file and put it in the target directory
mvn install: copy a copy of the jar package to the local repository
mvn deploy: install jar s into private servers
mvn build

3. Change the warehouse from user directory to user-defined directory

effect
to configure

Local warehouse download address extraction code: tjim

setting.xml

<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
	
	<!-- Local warehouse location-->
	<localRepository>D:\MavenRepository</localRepository>

	<pluginGroups>
	</pluginGroups>

	<proxies>
		<!--  Proxy server configuration :   
		               By default, we use  apache Provided maven Warehouse (Central warehouse)，  But this warehouse is sometimes unstable, 
					   Several more proxy servers can be configured here. When the central warehouse is not available, download from the proxy server.   -->
	</proxies>

	<!--  Configure the server where the warehouse is located( Private service   nexus )Login user name and password  -->
	<servers>
	    <!--
		<server>
			<id>nexus-releases</id>
			<username>admin</username>
			<password>admin123</password>
		</server>
		<server>
			<id>nexus-snapshots</id>
			<username>admin</username>
			<password>admin123</password>
		</server>
		-->
	</servers>

	<!--    Configure the address of the private server so that you don't have to download from the public server jar Package, but under the private server. The private server does not. Download from the private server to the public server.   -->
	<mirrors>
	    
		
	</mirrors>

	<profiles>
	
		<profile>
			<id>dev</id>
			<repositories>
				<repository>
					<id>aliyun</id>
					<url>http://maven.aliyun.com/nexus/content/groups/public</url>
					<releases>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</releases>
					<snapshots>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</snapshots>
				</repository>
				<repository>
					<id>central</id>
					<url>http://central.maven.org/maven2/</url>
					<releases>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</releases>
					<snapshots>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</snapshots>
				</repository>
				<repository>
					<id>clojars</id>
					<name>clojars</name>
					<url>http://clojars.org/repo/</url>
					<releases>
						<enabled>true</enabled>
					</releases>
					<snapshots>
						<enabled>true</enabled>
					</snapshots>
				</repository>
				<repository>
					<id>redhat</id>
					<name>redhat</name>
					<url>https://maven.repository.redhat.com/ga/</url>
					<releases>
						<enabled>true</enabled>
					</releases>
					<snapshots>
						<enabled>true</enabled>
					</snapshots>
				</repository>

			</repositories>

			<pluginRepositories>
				<pluginRepository>
					<id>aliyun</id>
					<url>http://maven.aliyun.com/nexus/content/groups/public</url>
					<releases>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</releases>
					<snapshots>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</snapshots>
				</pluginRepository>
				<pluginRepository>
					<id>central</id>
					<url>http://central.maven.org/maven2/</url>
					<releases>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</releases>
					<snapshots>
						<enabled>true</enabled>
						<updatePolicy>always</updatePolicy>
					</snapshots>
				</pluginRepository>
				<pluginRepository>
					<id>clojars</id>
					<name>clojars</name>
					<url>http://clojars.org/repo/</url>
					<releases>
						<enabled>true</enabled>
					</releases>
					<snapshots>
						<enabled>true</enabled>
					</snapshots>
				</pluginRepository>

			</pluginRepositories>
		</profile>
		

		<profile>
			<!-- to configure maven Used jdk Version, because if it is not configured, it is automatically adopted jdk1.4, In this way, the plug-in will be downloaded based on jdk1.4 Plug-in, running error  -->
			<id>jdk1.8</id>
			<activation>
				<activeByDefault>true</activeByDefault>
				<jdk>1.8</jdk>
			</activation>
			<properties>
				<maven.compiler.source>1.8</maven.compiler.source>
				<maven.compiler.target>1.8</maven.compiler.target>
				<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
			</properties>
		</profile>
	</profiles>
	<activeProfiles>
		<activeProfile>dev</activeProfile>
		<activeProfile>jdk1.8</activeProfile>
	</activeProfiles>
</settings>

term

1. Warehouse

Central warehouse
Private server: image warehouse (self built) - nexus
Local warehouse

2. Level of configuration file

Highest: only works for the current project, for example, POM xml
Intermediate: only works for the current user, for example ${user. Home} / m2/settings. xml
Low level: Works for projects using the current maven, for example, conf / settings. In the Maven installation package xml

3.settings.xml configuration

localRepository: location of the local repository
mirror
repository
agent
jdk version

4. goal commonly used by maven

Different commands will automatically download different plug-ins. maven runs in the form of plug-ins
mvn clean: clear the output directory, that is, delete the target directory
mvn compile: compile, that is, generate the target directory
mvn test: Test
Package in target: jar directory
mvn install: copy a copy of the jar package to the local repository
mvn deploy: install jar s into private servers
mvn build

5. Life cycle

Clean Lifecycle does some cleaning before a real build

pre-clean: Perform some tasks that need to be clean Previously completed work
clean: Remove all files generated by the last build
post-clean: Perform some tasks that need to be clean Work done immediately after

The core part of Default Lifecycle construction, including compilation, testing, packaging, deployment, etc
Site Lifecycle generates project reports, sites, and publishes sites