为什么maven有时无法解决依赖关系？

Question

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>

和Spring模块pom是（没有提到任何版本）：

<?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 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>

对于 Spring 模块，当我从 IntelliJ 重新加载所有 maven 项目时，它成功地解决了所有依赖关系，但对于 SpringBootLocalstack，如果我从 pom 文件中删除“版本”标签，它无法解决，示例：

     <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-java-sdk-core</artifactId>
              </dependency>

我得到：

Cannot resolve com.amazonaws:aws-java-sdk-core:unknown

我不想在这里提及任何具体版本。现在我的问题是：

为什么maven有时可以像上面的“Spring”模块解析依赖关系有时不能？（Spring我没有提到版本号的BootLocalstack模块）
我们如何才能实现 Maven 依赖项的兼容性安全？有没有插件（已经试过dependency analyzer和version maven plugin但是没有成功）
我们如何在不破坏现有项目功能的情况下将我们的旧项目升级到新的 Maven 依赖项？

提前致谢。

Answer 1

您已将 'org.springframework.boot' 声明为两个模块的父模块。因此，如果 'com.amazonaws' 等一些 jar 和工件在 'org.springframework.boot' 中不存在，它们将不会在您的项目中解析。这些依赖项不会在您项目的 'Spring' 模块中公布，您在其中声明的任何内容都可以在 'org.springframework.boot' 中找到，然后解析。如果你没有在你的 pom 中声明一个 'version' 标签，我想你的模块版本将考虑父版本（这里是 2.6.1）。

Answer 2

我认为 BOM（物料清单）可能会派上用场。如果我们使用 BOM，我们就不需要每次在同一个父 POM 下添加依赖项时都指定版本号。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>

为什么maven有时无法解决依赖关系？

Why maven sometimes can't resolve dependencies?

java

intellij-idea

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aws-sdk