SpringBoot多模块配置Maven依赖后无法导入OwnerService问题

• 在DataLoader类中无法实例化OwnerService，根因是无法从pet-clinic-data模块导入对应包。
• 已经在pet-clinic-web模块的pom文件中声明了pet-clinic-data依赖，导入依然失败。

pet-clinic-data 模块 pom.xml #

<?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>
        <artifactId>sfg-pet-clinic</artifactId>
        <groupId>guru.springframework</groupId>
        <version>0.0.2</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>pet-clinic-data</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <spring-boot.repackage.skip>true</spring-boot.repackage.skip>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                        <configuration>
                            <skip>true</skip>
                        </configuration>
                    </execution>
                </executions>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

pet-clinic-web 模块 pom.xml #

<?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>
        <artifactId>sfg-pet-clinic</artifactId>
        <groupId>guru.springframework</groupId>
        <version>0.0.2</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>pet-clinic-web</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <artifactId>pet-clinic-data</artifactId>
            <groupId>guru.springframework</groupId>
            <version>0.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>guru.springframework</groupId>
            <artifactId>pet-clinic-data</artifactId>
            <version>0.0.2</version>
            <scope>compile</scope>
        </dependency>

    </dependencies>

</project> 

1. 先清理重复依赖：pet-clinic-web的pom里重复声明了两次pet-clinic-data依赖，删掉其中任意一个即可，重复声明不会增强依赖效果，反而可能引发解析异常。
2. 核心问题是打包配置错误：pet-clinic-data作为公共依赖模块，被配置了Spring Boot的repackage打包逻辑，虽然写了skip配置，但配置位置在execution内部，实际没有生效，最终模块被打包成了Spring Boot可执行fat jar——这种jar的类文件都放在BOOT-INF/classes路径下，普通Maven依赖引用时无法识别到里面的类，自然会报导入失败。
   修复方式二选一：
   • 直接删掉pet-clinic-data模块里spring-boot-maven-plugin的全部配置，公共模块不需要打可执行包，Maven默认打出来的普通jar就能被其他模块正常依赖。
   • 如果要保留插件配置，就把skip配置移到插件全局层级，不要放在execution的配置里。
3. 配置改完后，在项目根目录执行mvn clean install，把修正后的pet-clinic-data安装到本地Maven仓库，再刷新IDE的Maven依赖、重新导入项目即可正常导入类。

内容的提问来源于stack exchange，提问作者Epitaph