引言

Maven是Java项目的标准构建工具。本文介绍Maven的核心功能和实战应用。

一、Maven核心概念

1.1 坐标（Coordinates）

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<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.7.0</version>
</dependency>

1.2 pom.xml结构

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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0">
    <modelVersion>4.0.0</modelVersion>
    
    <groupId>com.example</groupId>
    <artifactId>my-app</artifactId>
    <version>1.0.0</version>
    <packaging>jar</packaging>
    
    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    
    <dependencies>
        <!-- 依赖配置 -->
    </dependencies>
    
    <build>
        <plugins>
            <!-- 插件配置 -->
        </plugins>
    </build>
</project>

二、依赖管理

2.1 依赖范围

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<!-- compile：默认，编译和运行都需要 -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>5.3.20</version>
    <scope>compile</scope>
</dependency>

<!-- provided：编译需要，运行时由容器提供 -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
    <scope>provided</scope>
</dependency>

<!-- test：仅测试时需要 -->
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13.2</version>
    <scope>test</scope>
</dependency>

<!-- runtime：运行时需要 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.29</version>
    <scope>runtime</scope>
</dependency>

2.2 依赖传递

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<!-- 排除传递依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </exclusion>
    </exclusions>
</dependency>

2.3 依赖管理（父POM）

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<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>2.7.0</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

三、生命周期

3.1 三套生命周期

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# clean生命周期
mvn clean

# default生命周期
mvn compile      # 编译
mvn test         # 测试
mvn package      # 打包
mvn install      # 安装到本地仓库
mvn deploy       # 部署到远程仓库

# site生命周期
mvn site

3.2 常用命令

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# 清理并打包
mvn clean package

# 跳过测试打包
mvn clean package -DskipTests

# 安装到本地仓库
mvn clean install

# 运行Spring Boot项目
mvn spring-boot:run

# 查看依赖树
mvn dependency:tree

# 查看有效POM
mvn help:effective-pom

四、插件配置

4.1 编译插件

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<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.10.1</version>
            <configuration>
                <source>11</source>
                <target>11</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
    </plugins>
</build>

4.2 Spring Boot插件

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<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>2.7.0</version>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
        </execution>
    </executions>
</plugin>

五、多模块项目

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<!-- 父POM -->
<packaging>pom</packaging>
<modules>
    <module>module-common</module>
    <module>module-dao</module>
    <module>module-service</module>
    <module>module-web</module>
</modules>

<!-- 子模块 -->
<parent>
    <groupId>com.example</groupId>
    <artifactId>parent</artifactId>
    <version>1.0.0</version>
</parent>

总结

Maven核心：

  1. 依赖管理：统一管理项目依赖
  2. 生命周期：标准化构建流程
  3. 插件系统：扩展构建功能
  4. 仓库管理：本地和远程仓库

参考资料