[英]Why maven sometimes can't resolve dependencies?
I have a multimodule Maven project where parent pom is as follows我有一个多模块 Maven 项目,其中父 pom 如下
<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>groupId</groupId>
<artifactId>poc</artifactId>
<packaging>pom</packaging>
<version>1.0-SNAPSHOT</version>
<description>Root Maven project</description>
<modules>
<module>Spring</module>
<module>SpringBootLocalstack</module>
</modules>
</project>
and Spring module pom is (without mention any version):和 Spring 模块 pom 是(没有提及任何版本):
<?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">
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>Spring</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<version>3.2.0</version>
<executions>
<execution>
<id>analyze</id>
<goals>
<goal>analyze-only</goal>
</goals>
<configuration>
<failOnWarning>true</failOnWarning>
<outputXML>true</outputXML>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>2.7</version>
<configuration>
<excludes>
<exclude>org.apache.commons:commons-collections4</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>
SpringBootLocalstack module pom is: SpringBootLocalstack 模块 pom 是:
<?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">
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>SpringBootLocalstack</artifactId>
<properties>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
</properties>
<dependencies>
<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>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-dynamodb</artifactId>
<version>1.11.356</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-ssm</artifactId>
<version>1.11.665</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>io.awspring.cloud</groupId>
<artifactId>spring-cloud-aws-messaging</artifactId>
<version>2.3.0</version>
</dependency>
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-core</artifactId>
<version>1.11.356</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-messaging</artifactId>
<version>5.2.19.RELEASE</version>
</dependency>
<dependency>
<groupId>io.awspring.cloud</groupId>
<artifactId>spring-cloud-starter-aws-messaging</artifactId>
<version>2.3.0</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-to-slf4j</artifactId>
<version>2.11.1</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.4</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.8</version>
<executions>
<execution>
<id>analyze</id>
<goals>
<goal>analyze-only</goal>
</goals>
<configuration>
<failOnWarning>true</failOnWarning>
<outputXML>true</outputXML>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.asciidoctor</groupId>
<artifactId>asciidoctor-maven-plugin</artifactId>
<version>1.5.8</version>
<executions>
<execution>
<id>generate-docs</id>
<phase>prepare-package</phase>
<goals>
<goal>process-asciidoc</goal>
</goals>
<configuration>
<backend>html</backend>
<doctype>book</doctype>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.springframework.restdocs</groupId>
<artifactId>spring-restdocs-asciidoctor</artifactId>
<version>${spring-restdocs.version}</version>
</dependency>
</dependencies>
</plugin>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>2.7</version>
<configuration>
<excludes>
<exclude>org.apache.commons:commons-collections4</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>
For Spring Module, When I reload all maven projects from IntelliJ, it successfully resolve all dependencies but for SpringBootLocalstack if I remove "version" tag from pom file it failed to resolve, Example:对于 Spring 模块,当我从 IntelliJ 重新加载所有 maven 项目时,它成功解决了所有依赖项,但对于 SpringBootLocalstack,如果我从 pom 文件中删除“版本”标签,它无法解决,例如:
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-core</artifactId>
</dependency>
I am getting:我正进入(状态:
Cannot resolve com.amazonaws:aws-java-sdk-core:unknown无法解析 com.amazonaws:aws-java-sdk-core:unknown
I don't want to mention any specific version here.我不想在这里提及任何特定的版本。 Now my questions are:现在我的问题是:
Thanks in advance.提前致谢。
You have declared 'org.springframework.boot' as the parent module of both modules.您已将“org.springframework.boot”声明为两个模块的父模块。 So if some jars and artifacts like 'com.amazonaws' do not exist in 'org.springframework.boot', they won't be resolved in your project.因此,如果“org.springframework.boot”中不存在某些 jars 和“com.amazonaws”等工件,它们将不会在您的项目中得到解决。 These dependencies are not announced in 'Spring' module in your project and whatever you have declared in it, can be found in 'org.springframework.boot', then resolved.这些依赖项不会在您项目的“Spring”模块中公布,无论您在其中声明什么,都可以在“org.springframework.boot”中找到,然后解决。 If you do not declare a 'version' tag in your pom, I guess the version of the parent (here 2.6.1) will be considered for your module version.如果您没有在 pom 中声明“版本”标签,我猜您的模块版本将考虑父版本(此处为 2.6.1)。
I think BOM (Bill of Materials) may come into rescue.我认为 BOM(材料清单)可能会得到拯救。 If we use BOM, we don't need to specify version numbers each time we add dependencies under same parent POM.如果我们使用 BOM,我们不需要每次在同一个父 POM 下添加依赖项时都指定版本号。 For example:例如:
<!-- https://mvnrepository.com/artifact/com.amazonaws/aws-java-sdk-bom -->
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-bom</artifactId>
<version>1.12.138</version>
<type>pom</type>
<scope>import</scope>
</dependency>
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