1. common 模块

Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.1.8.RELEASE:repackage (repackage) on project online-common: Execution repackage of goal org.springframework.boot:spring-boot-maven-plugin:2.1.8.RELEASE:repackage failed: Unable to find a single main class from the following candidates [com.example.onlinecommon.valatiledemo.Main, com.example.onlinecommon.valatiledemo.MainDemo, com.example.onlinecommon.valatiledemo.MyRunnable]

根据以上提示，我删除了类 Main、MainDemo、MyRunnable中的main方法。
2. 继续打包

Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.1.8.RELEASE:repackage (repackage) on project online-common: Execution repackage of goal org.springframework.boot:spring-boot-maven-plugin:2.1.8.RELEASE:repackage failed: Unable to find main class

以上提示：我的common模块缺少main类，因为这是我的工具模块，因此不需要启动类。我把打包文件更改为

 <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <skip>true</skip>
                </configuration>
            </plugin>
        </plugins>
    </build>

跳过此模块的打包即可