repackage failed: Unable to find main class

1.错误信息
SpringBoot进行Maven install操作时报repackage failed: Unable to find main class -> [Help 1]的错误,信息如下

[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.0.4.RELEASE:repackage (default) on project qfxSpringbootReadPropertiesDemo: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:2.0.4.RELEASE:repackage failed: Unable to find main class -> [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/PluginExecutionException

2.原因
因为没有正式环境的入口类,项目结构如下:

3.解决方案
pom.xml文件的<build>中指定入口类,代码如下

<configuration>
        <mainClass>com.qfx.App</mainClass>
</configuration>

如图

再次执行 Maven install,一切正常