作用:定位父项目的坐标标签,子项目可以直接继承父项目的依赖包,实现所有子项目共用相同的依赖包。
举例:
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.4.RELEASE</version> </parent>
作用:父子项目依赖的版本管理。
需要注意的是:
<!--只是对版本号进行管理,不会实际引入jar--> <dependencyManagement> <dependencies> <dependency> <!--jar包身份限定--> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <!--版本号的声明--> <version>3.2.7</version> </dependency> </dependencies> </dependencyManagement> <!--会实际下载声明的依赖jar包--> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <!--不声明version 标签,则会继承dependencyManagement--> </dependency> </dependencies>
<!--parent-module父模块pom.xml--> <properties> <!--统一管理jar包版本。集中在父模块properties标签中定义所有依赖的版本号。--> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <org.eclipse.persistence.jpa.version>1.2.6</org.eclipse.persistence.jpa.version> <javaee-api.version>1.8</javaee-api.version> </properties> <dependencyManagement> <!--定义公共依赖的版本号--> <dependencies> <dependency> <groupId>org.eclipse.persistence</groupId> <artifactId>org.eclipse.persistence.jpa</artifactId> <version>${org.eclipse.persistence.jpa.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>${javaee-api.version}</version> </dependency> </dependencies> </dependencyManagement>
<!--son-module子模块pom.xml--> <!--继承父类--> <parent> <!--声明父类的身份信息--> <artifactId>parent-module</artifactId> <groupId>com.ppd</groupId> <version>0.0.1-SNAPSHOT</version> <!--声明父类的pom文件路径--> <relativePath>../parent-module/pom.xml</relativePath> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>son-module</artifactId> <packaging>ejb</packaging> <!--依赖关系--> <dependencies> <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <!--未声明则继承父类version、scope--> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <!--声明则不继承父类version--> <version>1.8<version/> <!--继承父类scope--> </dependency> <dependency> <groupId>org.eclipse.persistence</groupId> <artifactId>org.eclipse.persistence.jpa</artifactId> <!--未声明则继承父类version--> <scope>provided</scope> </dependency> </dependencies>
作用:在pom.xml中的properties标签下声明相应的版本信息,然后在dependency下引用的时候用${spring-version}就可以引入该版本jar包了。
举例:
<properties> <spring-version>4.3.7.RELEASE</spring-version> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${spring-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring-version}</version> </dependency> </dependencies>