第一步： 父项目jar改pom

第二步 新建子项目 new->Module->Maven->Next-finsh

第三步修改pom
3.1父模块的module有子模块

 <modules>
        <module>server</module>
 </modules>
<packaging>pom</packaging>
//去除build,父模块不构建

3.2子模块的parent指向父模块

<artifactId>server</artifactId>
<!--将build移入-->
<build>
        <finalName>${parent.artifactId}-${project.artifactId}-${project.version}</finalName>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <targetPath>${project.build.directory}${file.separator}classes</targetPath>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <!--这里必须包含.xml否则Mybatis的xml无法打包-->
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>


        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.4.4</version>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.2.0</version>
                <configuration>
                    <excludes>
                        <exclude>application.yml</exclude>
                        <exclude>platform.properties</exclude>
                        <exclude>log4j.properties</exclude>
                    </excludes>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.3.0</version>
                <configuration>
                    <appendAssemblyId>false</appendAssemblyId>
                    <descriptors>
                        <descriptor>build/package.xml</descriptor>
                    </descriptors>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
                <version>3.1.1</version>
                <dependencies>
                    <dependency>
                        <groupId>com.puppycrawl.tools</groupId>
                        <artifactId>checkstyle</artifactId>
                        <version>8.36</version>
                    </dependency>
                </dependencies>
                <configuration>
                    <configLocation>build/hongcheng_checkstyle.xml</configLocation>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>3.0.0-M5</version>
                <configuration>
                    <argLine>
                        @{argLine}
                        -javaagent:${settings.localRepository}/com/alibaba/testable/testable-agent/${testable.version}/testable-agent-${testable.version}.jar
                    </argLine>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.jacoco</groupId>
                <artifactId>jacoco-maven-plugin</artifactId>
                <version>0.8.7</version>
                <executions>
                    <execution>
                        <id>default-prepare-agent</id>
                        <goals>
                            <goal>prepare-agent</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>default-report</id>
                        <phase>test</phase>
                        <goals>
                            <goal>report</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

        </plugins>

    </build>

第四步–移动项目
直接把java下的com包拖到对应位置新模块的src下(用文件夹的方式复制，不要在idea里面复制，部分内容会更改)，删除父模块的src