Maven中dependencyManagement标签的作用

快来打我* 2022-09-02 13:54 199阅读 0赞

## 一、作用 ##

使用dependencyManagement可以**统一**管理项目中依赖包的**版本号**，当需要变更版本号时只需在父pom中修改即可；如果某个子项目需要指定一个特殊的版本号时，只需要在自己项目的pom.xml中显示声明一个版本号即可，此时子项目会使用自己声明的版本号，而不继承父项目的版本号

## 二、dependencyManagement与dependencies的区别 ##

*  dependencies相对于dependencyManagement，所有声明在dependencies里的依赖都会自动引入，并默认被所有的子项目继承
 *  dependencyManagement里只是声明依赖，并不会自动引入，因此子项目需要显示声明依赖。在子项目中声明了依赖项，且没有指定具体版本，才会从父项目中继承该项，并且version和scope都读取自父pom；另外如果子项目中指定了版本号，则会使用子项目中指定的版本

⚠️注意：一个无子工程的独立工程中如果使用dependencyManagement，那么它自己的pom.xml文件引入的依赖也可以不指定版本

<?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.ume.qa</groupId>
        <artifactId>SpringCloudGateway</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
            <spring-cloud.version>3.0.1</spring-cloud.version>
        </properties>
    
        <dependencies>
            <dependency>
            	<groupId>org.springframework.boot</groupId>
            	<artifactId>spring-boot-starter-actuator</artifactId>
        	</dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-webflux</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-gateway</artifactId>
                <version>3.0.3</version>
            </dependency>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
                <exclusions>
                    <exclusion>
                        <artifactId>spring-cloud-context</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                    <exclusion>
                        <artifactId>spring-cloud-commons</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                    <exclusion>
                        <artifactId>spring-cloud-starter</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                </exclusions>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-bootstrap</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
                <version>3.0.2</version>
                <exclusions>
                    <exclusion>
                        <artifactId>spring-cloud-commons</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                    <exclusion>
                        <artifactId>spring-cloud-starter</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                </exclusions>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-loadbalancer</artifactId>
                <version>3.0.2</version>
                <exclusions>
                    <exclusion>
                        <artifactId>spring-cloud-commons</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                    <exclusion>
                        <artifactId>spring-cloud-context</artifactId>
                        <groupId>org.springframework.cloud</groupId>
                    </exclusion>
                </exclusions>
            </dependency>
        </dependencies>
    
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-dependencies</artifactId>
                    <version>2.4.2</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                <dependency>
                    <groupId>com.alibaba.cloud</groupId>
                    <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                    <version>2.2.5.RELEASE</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    </project>