今天,我们来了解下如何管理和优化父项目和子模块的依赖包版本,又或者我们希望子项目B不需要全部依赖父项目A的内容,避免一股脑全部导入。
首先,来看四个pom文件:
1、demo-parent
<?xml version="1.0" encoding="UTF-8"?>
<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.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>demo-parent</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.5.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<modules>
<module>demo-apply</module>
<module>demo-common</module>
<module>demo-static</module>
</modules>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
2、demo-apply
<?xml version="1.0" encoding="UTF-8"?>
<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>
<artifactId>demo-apply</artifactId>
<packaging>jar</packaging>
<name>demo-apply</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath><!-- lookup parent from repository -->
</parent>
<dependencies>
<!-- 加入其余模块的依赖 -->
<dependency>
<groupId>com.demo</groupId>
<artifactId>demo-common</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.demo</groupId>
<artifactId>demo-static</artifactId>
<version>0.0.1-SNAPSHOT</version>
<type>war</type>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<!-- 当所依赖的其他模块,有启动类的时候,需要以下配置,指定唯一启动类,
本次事例未涉及其他模块有启动类,可自行测试 -->
<configuration>
<!-- 指定该Main Class为全局的唯一入口 -->
<mainClass>com.demo.demoapply.DemoApplyApplication</mainClass>
<layout>ZIP</layout>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal><!--可以把依赖的包都打包到生成的Jar包中-->
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
3、demo-static
<?xml version="1.0" encoding="UTF-8"?>
<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>
<artifactId>demo-static</artifactId>
<packaging>war</packaging>
<name>demo-static</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath><!-- lookup parent from repository -->
</parent>
<dependencies>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
4、demo-common
<?xml version="1.0" encoding="UTF-8"?>
<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>
<artifactId>demo-common</artifactId>
<packaging>jar</packaging>
<name>demo-common</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath><!-- lookup parent from repository -->
</parent>
<dependencies>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
很明显,我们的demo-parent为父项目,demo-apply为应用入口,demo-common放的应该是共用工具类,demo-static应该是共用的静态文件,如页面等,demo-apply依赖两者。
好,看到这里,就有疑问了,按理来说,demo-static,存放页面,打包成war包,应该不需要可以运行,那么也就不需要依赖springboot的包,那么我们进行如下改变:
demo-parent:
<?xml version="1.0" encoding="UTF-8"?>
<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.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>demo-parent</name>
<description>Demo project for Spring Boot</description>
<!-- 删除 -->
<!--<parent>-->
<!--<groupId>org.springframework.boot</groupId>-->
<!--<artifactId>spring-boot-starter-parent</artifactId>-->
<!--<version>2.0.5.RELEASE</version>-->
<!--<relativePath/> <!– lookup parent from repository –>-->
<!--</parent>-->
<modules>
<module>demo-apply</module>
<module>demo-common</module>
<module>demo-static</module>
</modules>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<version>2.0.5.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>2.0.5.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<version>2.0.5.RELEASE</version>
<scope>test</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
demo-apply
<?xml version="1.0" encoding="UTF-8"?>
<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>
<artifactId>demo-apply</artifactId>
<packaging>jar</packaging>
<name>demo-apply</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../pom.xml</relativePath><!-- lookup parent from repository -->
</parent>
<dependencies>
<!-- 加入其余模块的依赖 -->
<dependency>
<groupId>com.demo</groupId>
<artifactId>demo-common</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.demo</groupId>
<artifactId>demo-static</artifactId>
<version>0.0.1-SNAPSHOT</version>
<type>war</type>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<!-- 当所依赖的其他模块,有启动类的时候,需要以下配置,指定唯一启动类,
本次事例未涉及其他模块有启动类,可自行测试 -->
<configuration>
<!-- 指定该Main Class为全局的唯一入口 -->
<mainClass>com.demo.demoapply.DemoApplyApplication</mainClass>
<layout>ZIP</layout>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal><!--可以把依赖的包都打包到生成的Jar包中-->
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
大功告成,虽然这样是OK了,大家查看依赖发现也对,demo-static和demo-common,已经不依赖springBoot,但是有心人一定会问,demo-parent为何删除这一段:
<!-- 删除 -->
<!--<parent>-->
<!--<groupId>org.springframework.boot</groupId>-->
<!--<artifactId>spring-boot-starter-parent</artifactId>-->
<!--<version>2.0.5.RELEASE</version>-->
<!--<relativePath/> <!– lookup parent from repository –>-->
<!--</parent>-->
首先,告诉大家这一段从哪里来的,idea在生成springBoot项目的时候,会采取官方建议,默认引入该父项目。
那么问题又来了,这个父项目到底是个啥,我们默认要引入他,大家可以点击进去查看,其实他只是个pom文件,管理了一些默认的配置信息,这样才能做到,我们在默认生成项目的时候,发现我们的dependency中不需要引入版本,应为他会集成父Pom文件的版本信息。
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
...
</dependencies>
</dependencyManagement>
既然知道,原来是这么回事,那我们顺便查下SpringBoot的官网介绍吧,是否还有更好的方式。
果真,还有一种方式:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>1.5.1.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
请注意,它的 type 是 pom,scope 是 import,这种类型的 dependency 只能在 dependencyManagement 标签中声明。
同样我们在点进去看,原来这个POM文件已经默认给我们使用dependencyManagement声明了很多依赖,我们如果需要直接在我们的dependency中加入依赖就行,而无需指定版本。
这样demo-parent的Pom文件就变成了这个样子:
<?xml version="1.0" encoding="UTF-8"?>
<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.demo</groupId>
<artifactId>demo-parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>demo-parent</name>
<description>Demo project for Spring Boot</description>
<modules>
<module>demo-apply</module>
<module>demo-common</module>
<module>demo-static</module>
</modules>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.0.0.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
这样parent项目的POM依赖就会特别清晰。
注释:dependencyManagement 包裹的dependencies只有声明作用,不会实际导入,另外关于maven中的继承、聚合等多多了解,就能很好的理解上述的内容。
源码:https://github.com/ATSJP/Study-Springboot-Demo.git,
请切换为DV_2018_10_15分支查看。
好的东西都在这里>>> 官网:Spring官网