Maven is a widely used build tool in Java projects, and its core value lies in simplifying dependency management and unified construction processes. 1. Before installing Maven, make sure that JDK is installed. After downloading, configure the environment variables MAVEN_HOME and PATH, Windows users set %MAVEN_HOME%\bin, Mac/Linux users modify the .bash_profile or .zshrc file, and the local repository path can be customized through .m2/settings.xml. 2. Create a Maven project by executing mvn archetype:generate to generate a standard structure, or create a new Maven project in the IDE to automatically complete. 3. Use pom.xml to manage dependencies, declare groupId, artifactId and version to automatically download the corresponding jar package and deal with dependency delivery issues. You can find the dependency format through Maven Central. Multi-module projects use to manage the version uniformly. 4. Commonly used construction commands include mvn compile, test, package, install and clean. They support the combination of mvn clean packages. By configuring plug-ins, you can customize the build behavior, such as specifying the compiler version to avoid compatibility issues. Master these core contents and use Maven to efficiently build and manage projects.

Maven is a widely used build tool in Java projects. It not only simplifies dependency management, but also unifies the structure and construction process of the project. If you are just starting to get involved in Maven, you may feel that the configuration is a bit complicated, but in fact, it is very convenient to use as long as you master a few core concepts.

1. Installation and basic configuration

Before using Maven, you must first make sure that you have installed the JDK (Java Development Kit) because Maven is based on Java. Then you can go to the official website to download the Maven package, decompress and configure the environment variables MAVEN_HOME and PATH , and then enter mvn -v on the command line to see if the version information can be displayed normally.

• Set environment variables under Windows:
  • MAVEN_HOME: Point to the directory after decompression
  • PATH Add %MAVEN_HOME%\bin
• Mac/Linux users modify the .bash_profile or .zshrc file to add paths

By default, Maven's local repository will be placed in .m2/repository in the user directory. If you want to change the location, you can customize the repository path in the .m2/settings.xml file.

2. Create a Maven project

The easiest way is to generate a standard Maven project structure via the command line:

 mvn archetype:generate -DgroupId=com.example -DartifactId=demo-app -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

This command creates a Java project containing the basic directory structure, including the source directory src/main/java and the test directory src/test/java . pom.xml is the core configuration file of the entire Maven project, and all dependencies and plug-ins are written here.

If you are using an IDE (such as IntelliJ IDEA or Eclipse), you can also directly choose to create a new Maven project, and the IDE will automatically generate these structures for you.

3. Use POM to manage dependencies

The most powerful thing about Maven is dependency management. You only need to declare the library you want to use in the pom.xml file, and Maven will automatically download the corresponding jar package from the central repository or the remote repository you configured and handle the dependency transfer problem.

For example, add a common log library Log4j:

 <dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

A few points to note:

• Make sure groupId , artifactId and version are correct
• You can go to Maven Central to find the required dependency format
• If there are multiple modules in the project, you can use <dependencyManagement> to manage the version uniformly

By default, Maven will automatically download dependencies during compilation and packaging. You can also manually execute mvn dependency:resolve to pull all dependencies in advance.

4. Construction and common commands

Maven provides a standard life cycle to complete the project construction process, mainly including:

• mvn compile : compile the main program code
• mvn test : Run test code (not deployed or packaged)
• mvn package : packaged into jar/war files, usually used for deployment
• mvn install : Install the project to the local repository for reference by other projects
• mvn clean : cleans up the generated files that were built before

You can use these commands in combination, such as mvn clean package that means clean first and then package.

Sometimes you also need to customize the build behavior, which can be implemented by configuring plugins in pom.xml , for example:

 <build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>

This allows you to specify the compiler version to avoid compatibility issues.

Basically that's all. It is not difficult to get started with Maven. The key is to understand the role of POM files and dependency management mechanism. In actual development, many companies will also use Maven in combination with CI/CD tools to improve the level of automation.

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