Java classpath build with "spring-boot-maven-plugin" does not work - spring-boot

Question

Try to build a classpath with jars to invoke my program with java-command
"java -cp %classpath% %mainclass%".
But can't manage to get to it run.
When building the jar with "spring-boot-maven-plugin" I always get an error because mainclass cannot be found.
When building the jar with "maven-jar-plugin/maven-assembly-plugin", the Spring environment is not found.
I have setup a small sample project to test and show. It would be great if someone could give me some help here.
My project looks like this:
mysample-base (has a packaging of "pom" and has module "mysample-frontend")
mysample-frontend (has a packaging of "pom" and has module "mysample-frontend-programs")
mysample-frontend-programs (has a packaging of "jar" and contains the programs).
These are the poms:
mysample-base/pom.xml
<groupId>com.mysamples</groupId>
<artifactId>mySamples-base</artifactId>
<version>1.0.0</version>
<packaging>pom</packaging>
<properties>
<java.version>1.8</java.version>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<revision>1.0.0</revision>
<targetJarDir>E:/$SysProg/mySample/RUN/lib</targetJarDir>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.3.RELEASE</version>
</parent>
<modules>
<module>mySamples-frontend</module>
</modules>
<dependencies>
<!-- ***************************************************************************************************
* Springboot *************************************************************************************************** -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web-services</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- ***************************************************************************************************
* Database Access *************************************************************************************************** -->
<!-- https://mvnrepository.com/artifact/org.codehaus.mojo/jaxb2-maven-plugin -->
<dependency>
<groupId>org.codehaus.mojo</groupId>
<artifactId>jaxb2-maven-plugin</artifactId>
<version>2.5.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
</dependencies>
<build>
<plugins>
<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>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>2.9.1</version>
<configuration>
<show>private</show>
<nohelp>true</nohelp>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<phase>install</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${targetJarDir}</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
mysample-frontend/pom.xml
<artifactId>mySamples-frontend</artifactId>
<packaging>pom</packaging>
<parent>
<groupId>com.mysamples</groupId>
<artifactId>mySamples-base</artifactId>
<version>1.0.0</version>
</parent>
<modules>
<module>mySamples-frontend-programs</module>
</modules>
mysample-frontend-progams/pom.xml - with "spring-boot-maven-plugin"
<artifactId>mySamples-frontend-programs</artifactId>
<version>1.0.0</version>
<packaging>jar</packaging>
<parent>
<groupId>com.mysamples</groupId>
<artifactId>mySamples-frontend</artifactId>
<version>1.0.0</version>
</parent>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>2.3.4.RELEASE</version>
<configuration>
<fork>true</fork>
<mainClass>com.mysamples.calling.MainCalling</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
mysample-frontend-progams/pom.xml - with "maven-assembly-plugin"
<artifactId>mySamples-frontend-programs</artifactId>
<version>1.0.0</version>
<packaging>jar</packaging>
<parent>
<groupId>com.mysamples</groupId>
<artifactId>mySamples-frontend</artifactId>
<version>1.0.0</version>
</parent>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.3.0</version>
<configuration>
<archive>
<manifestEntries>
<Build-Version>${project.version}</Build-Version>
<Built-By>${user.name}</Built-By>
<Build-Jdk>${java.version}</Build-Jdk>
<Build-Time>${maven.build.timestamp}</Build-Time>
<Build-Number>${buildNumber.value}</Build-Number>
<Build-YearStarted>2020</Build-YearStarted>
<DeveloperName>Ulrich Schmidt</DeveloperName>
</manifestEntries>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
I' m running this command:
cd /D .....
SET CLASSPATH=mySamples-frontend-programs-1.0.0.jar
java -Duser.language=en -cp mySamples-frontend-programs-1.0.0.jar com.mysamples.calling.MainCalling
In case of using "spring-boot-maven-plugin" for building jar, I get this message:
Error: Could not find or load main class com.mysamples.calling.MainCalling
Looking in the jar file shows, that the main-class is stored to "ROOT-INF/classes". In the root-path of the jar I can only find the spring framework.
In case of using "maven-assembly-plugin" for building jar, I get this message:
java.lang.IllegalArgumentException: No auto configuration classes found in META-INF/spring.factories. If you are using a custom packaging, make sure that file is correct.
at org.springframework.util.Assert.notEmpty(Assert.java:467)
at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getCandidateConfigurations(AutoConfigurationImportSelector.java:180)
at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getAutoConfigurationEntry(AutoConfigurationImportSelector.java:123)
at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector$AutoConfigurationGroup.process(AutoConfigurationImportSelector.java:434)
at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGrouping.getImports(ConfigurationClassParser.java:878)
at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.processGroupImports(ConfigurationClassParser.java:808)
at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorHandler.process(ConfigurationClassParser.java:779)
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:192)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:319)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:236)
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:280)
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:96)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:707)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:533)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
at com.mysamples.calling.MainCalling.main(MainCalling.java:27)
The both of the classes created are:
#ComponentScan({"com.mysamples"})
#SpringBootApplication
public class MainCalling {
private static final Logger LOGGER = LoggerFactory.getLogger(MainCalling.class);
#Autowired
public MainCalling(final ClassToBeCalled toBeCalled) {
toBeCalled.isCalled();
}
public static void main(String[] args) {
try {
SpringApplication.run(MainCalling.class);
} catch (Exception e) {
LOGGER.error("", e);
System.exit(-1);
}
}
and
#Service
public class ClassToBeCalled {
private static final Logger LOGGER = LoggerFactory.getLogger(ClassToBeCalled.class);
public void isCalled() {
LOGGER.info("have been called");
}
}

Answer 1

I think I got it. "spring-boot-maven-plugin" does not allow for the command "java -cp ${classpath} ${chosenMain}". You have to use "java -jar ${classpath}" - the way the jar is created, by only springframework in the rootDir of the jar does not nable for calling directly the designated mainClass. The way how to invoke multiple main-Classes is described in "Running spring boot with multiple main classes"
Thanks to #khmarbaise for the hint. Couldn't believe in the first place, but after some reading, I got, he is right.