Maven的继承以及import作用域

Maven的pom文件中可继承的元素包括:

  groupId:项目ID,项目坐标核心元素

  version:项目版本

  description:描述信息

  organization:组织信息

  inceptionYear:创始年份

  url:项目URL地址

  developers:开发者信息

  distributionManagement:项目部署配置

  issueManagement:项目缺陷跟踪系统信息

  ciManagement:项目持续集成系统信息

  scm:项目版本控制系统信息

  mailingLists:邮件列表

  properties:自定义属性

  dependencies:依赖配置

  dependencyManagement:依赖配置管理

  repositories:仓库配置

  build:构建信息,包括源码目录,输出目录,插件配置,插件管理配置

  reporting:项目的报告输出目录配置,报告插件配置。

大部分配置都是说明性质的信息配置,这里主要介绍依赖配置,依赖管理配置,插件配置,插件管理配置。示例如下:

  父项目配置文件:

<!-- 父项目本身除了一个pom.xml文件,不包含其它内容 -->
<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>

    <groupId>com.cbm.stu</groupId>
    <artifactId>maven-study-parent</artifactId>
    <version>1.0.0</version>
    <packaging>pom</packaging>    <!-- 父项目的packing必须为pom -->

    <name>maven-study-parent</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <!-- dependencies标签中的依赖会被子项目完全继承:即父项目中有的依赖都会出现在子项目中 -->
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>
    </dependencies>
    
    <!-- 依赖管理中声明的依赖并不会被子项目直接继承,在子项目中需要声明,但是只需要声明groupId和artifactId -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.40</version>
            </dependency>
            <dependency>
                <groupId>org.postgresql</groupId>
                <artifactId>postgresql</artifactId>
                <version>42.0.0</version>
            </dependency>
            <dependency>
                <groupId>redis.clients</groupId>
                <artifactId>jedis</artifactId>
                <version>2.9.0</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.10</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <!-- 插件管理,可供子项目继承 -->
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>2.1</version>
                    <configuration>
                        <source>1.7</source>
                        <target>1.7</target>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

子项目配置:

<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>

    <!-- parent标签声明继承的父项目信息 -->
    <parent>
        <groupId>com.cbm.stu</groupId>
        <artifactId>maven-study-parent</artifactId>
        <version>1.0.0</version>
        <!-- 父项目的pom.xml相对于当前项目的位置 -->
        <relativePath>../maven-study-parent/pom.xml</relativePath>
    </parent>

    <!-- groupId可以继承,也可以覆盖,通常不需要覆盖 -->
    <groupId>com.cbm.stud</groupId>
    <!-- 不可继承,子项目坐标的关键属性 -->
    <artifactId>maven-study-account</artifactId>
    <version>1.0.2</version>
    <packaging>jar</packaging>

    <name>maven-study-account</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <!-- 父项目中dependencies标签声明的依赖被直接继承,例如mybatis包 -->
    <dependencies>
        <!-- 继承自父项目的依赖,只需指明groupId和artifactId -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <!-- 继承自父项目的插件依赖,此处省略也可继承 -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

 使用import属性实现依赖的多继承:

父项目a:

<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>

    <groupId>com.cbm.stu</groupId>
    <artifactId>maven-parent-a</artifactId>
    <version>1.0.0</version>
    <packaging>pom</packaging>

    <name>maven-parent-a</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.10</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

父项目b:

<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>

    <groupId>com.cbm.stu</groupId>
    <artifactId>maven-parent-b</artifactId>
    <version>1.0.0</version>
    <packaging>pom</packaging>

    <name>maven-parent-b</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.4.1</version>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.40</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

继承 a 和 b 的子项目:

<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>

    <groupId>com.cbm.stu</groupId>
    <artifactId>maven-study-mail</artifactId>
    <version>2.1</version>
    <packaging>jar</packaging>

    <name>maven-study-mail</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!-- 此处继承了a 和 b 两个项目,type为pom,scope 为 import -->
            <dependency>
                <groupId>com.cbm.stu</groupId>
                <artifactId>maven-parent-a</artifactId>
                <version>1.0.0</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.cbm.stu</groupId>
                <artifactId>maven-parent-b</artifactId>
                <version>1.0.0</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <!-- 从继承的父项目中继承依赖 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

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The end!

原文地址:https://www.cnblogs.com/techroad4ca/p/6512591.html