不使用spring-boot-starter-parent

如果想不使用spring-boot-starter-parent，可以这样配置：
（1）配置使用spring-boot-dependencies

<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.0.4.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

        </dependencies>
    </dependencyManagement>

注意：一定要知名是pom import，否则会有问题。

(2)配置spring-boot-maven-plugin

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

注意：
(1) 如果不使用：maven-compiler-plugin，那么
a)从App.main运行不会有问题
b)mvn pacakge或者mvn spring-boot:run会出现问题：

INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.951 s
[INFO] Finished at: 2020-08-15T10:19:47+08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project com.demo: Compilation failure: Compilation failure: 
[ERROR] 不再支持源选项 5。请使用 7 或更高版本。
[ERROR] 不再支持目标选项 5。请使用 7 或更高版本。
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

(2) spring-boot-maven-plugin一定要配置goal为repackage，否则mvn package无法正常工作。mvn package可以正常打包，但是java -jar xxx 运行jar包会出现错误：

➜  comdemo1 java -jar /Users/apple/work/code/springboot/comdemo1/target/com.demo-1.0-SNAPSHOT.jar
/Users/apple/work/code/springboot/comdemo1/target/com.demo-1.0-SNAPSHOT.jar中没有主清单属性