Maven basic knowledge study notes

Table of contents

1. Introduction to Maven

2. Maven installation and configuration

Three, the basic use of Maven

4. IDEA configures Maven

1. IDEA configures the Maven environment

2. IDEA creates a Maven project

3. IDEA imports Maven project

1. Introduction to Maven

Maven is a project management tool , a tool specially used to manage and build Java projects . It contains an object model. A standard set, a dependency management system, that Maven uses to run plugin goals and logic defined in lifecycle phases.

Its main functions:

Provides a standardized project structure
Provides a standardized build process (compile, test, package, release...)
Provides a set of dependency management mechanisms

Its core functions:

The core function of Maven is to reasonably describe the dependencies between projects , that is, to obtain the jar package through the configuration of the pom.xml file without manually adding the jar package

Maven model:

2. Maven installation and configuration

Download Maven

Configure the environment variable MAVEN_HOME as the bin directory of the installation path

Configure the local warehouse: modify <localRepository> in conf/settings.xml to a specified directory

Configure Alibaba Cloud Private Server: Modify the <mirrors> tag in conf/settings.xml and add sub-tags to it

Step 1: Download Maven

Maven download address : https://maven.apache.org/download.cgi maven official website

Note: Binary is an executable version , which has been compiled and can be used directly. Source is the source code version , which needs to be compiled into executable software before it can be used. We choose the compiled windows version to install: choose the zip version (linux choose tar.gz)

Successfully downloaded files:

After the download is complete, unzip it to the path you want to install:

Step 2: Maven environment variable configuration

1. Advanced system settings in the computer: right click to start - find settings - open settings - enter advanced settings - click to view advanced system settings

2. Click Environment Variables

3. Create a new system variable

4. Create your maven installation path

5. Edit the path path:

6. Set a new path

7. Verify that maven is configured successfully

Since this is the version I installed before, I have not changed it. If the installation is performed according to the above operation, the version model of maven should be: 3.8.6;

Step 3: Configure the local warehouse

1. Find the conf folder under the maven installation path and open the folder;

2. Find the settings.xml file under the conf file and open this file

3. Open it with vs or other programming software on the computer, and find the position where the text appears in the red box below;

4. Create a new file in the maven folder as your own local warehouse, and the name of the warehouse can be customized;

5. Copy this line of code from the comment, and replace the code in <localRepository> with the address of the local warehouse you created;

Step 4: Configure Alibaba Cloud private server; in order to improve the download speed of the package

1. Find the conf folder under the maven installation path and open the folder;

2. Find the settings.xml file under the conf file and open this file

3. Open it with vs or other programming software on the computer, and find the mirrors node in the settings.xml configuration file, as shown in the figure below

4. Add the following configuration (note that it should be added between the two tags <mirrors> and </mirrors>, and the other configurations are the same), and put it in front of the default node.

直接复制下列这段代码，然后粘贴到<mirrors>标签下面
<mirror>  
<id>alimaven</id>  
<name>aliyun maven</name>  
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<mirrorOf>central</mirrorOf>          
</mirror>

Three, the basic use of Maven

Maven's common commands:

compile : compile

clean: clean up

test: test

package: package

install: install

4. IDEA configures Maven

IDEA configures the Maven environment

IDEA creates a Maven project

IDEA imports Maven project

dependency management

Detailed explanation of Maven coordinates

What are coordinates?

Coordinates in Maven are unique identifiers of resources;

Use coordinates to define projects or to introduce project dependencies

The main components of Maven coordinates

groupId: defines the current Maven project affiliated organization name

artifactId: defines the current Maven project name

version: defines the current project version number

1. IDEA configures the Maven environment

1.1 Select File--Settings in IDEA

1.2 search maven

1.3 Set IDEA to use locally installed Maven, and modify the configuration file path

2. IDEA creates a Maven project

2.1 Create a module, select Maven, and click next

2.2 Fill in the module name, coordinate information, click finish, the creation is complete

2.3 Write the program and run it

You can create your own class under the java package in the main of the created module to write code and run it

3. IDEA imports Maven project

Supplement: plugins used in maven

Configure the Maven-Helper plugin

1. Select File-->Settings in IDEA

2. Select Plugins

3. Search for Maven, select the first Maven hepler, click install to install, and click Accpet in the pop-up panel

4. Restart IDEA

The purpose of configuring this plugin: Right-click on the implementation class, and the run maven button will appear to make maven run more efficiently

4. Dependency management

4.1 Import jar package using coordinates

Write the <dependencies> tag in pom.xml
Use <dependency> in the <dependencies> tag to introduce coordinates
define coordinates groupld, artifactld, version
Click the refresh button to make the coordinates take effect (automatic configuration can be configured to take effect)

4.1 Shortcuts for importing jar packages using coordinates (supplement)

Press alt+insert in pom.xml and select Dependency
Search for the corresponding coordinates in the pop-up panel, then double-click to select the corresponding target
Click the refresh button to make the coordinates take effect

4.2 Range of coordinate dependence

By setting the dependency scope (scope) of the coordinates, you can set the scope of the corresponding jar package: compilation environment, test environment, and running environment ; <scope> default value: compile

compile : compile, test, run
test : test
provided : compile, test
runtime : test, run
system : compile, test