SpringBoot: Defining the main class in pom.xml file - spring

Question

I've generated a Spring Boot web application using Spring Initializer, embedded Tomcat, Thymeleaf template engine.Technologies used: Spring Boot 1.4.2.RELEASE, Spring 4.3.4.RELEASE, Thymeleaf 2.1.5.RELEASE, Tomcat Embed 8.5.6, Maven 3, Java 8.
I have this pom.xml file,
and I generate the war using this command
mvn clean package -DskipTests -Dspring.profiles.active=pebloc,war -DAPPKEY=pebloc
pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.bookcloud</groupId>
<artifactId>bookcloud</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>bookcloud</name>
<description>Book Cloud </description>
<profiles>
<profile>
<id>jar</id>
<properties>
<spring.boot.mainclass>com.bookcloud.iot.BookCloudApplication</spring.boot.mainclass>
</properties>
</profile>
<profile>
<id>war</id>
<properties>
<spring.boot.mainclass>com.bookcloud.iot.BookCloudApplicationWar</spring.boot.mainclass>
</properties>
</profile>
</profiles>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-mail</artifactId>
</dependency>
<dependency>
<groupId>it.ozimov</groupId>
<artifactId>spring-boot-email-core</artifactId>
<version>0.5.1</version>
</dependency>
<dependency>
<groupId>it.ozimov</groupId>
<artifactId>spring-boot-thymeleaf-email</artifactId>
<version>0.5.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-batch</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/com.icegreen/greenmail -->
<dependency>
<groupId>com.icegreen</groupId>
<artifactId>greenmail</artifactId>
<version>1.5.3</version>
<optional>true</optional>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</dependency>
<!-- hot swapping, disable cache for template, enable live reload -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Camden.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<mainClass>${spring.boot.mainclass}</mainClass>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
but I still got this error:
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.RELEASE:repackage (default) on project bookcloud: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.RELEASE:repackage failed: Unable to find a single main class from the following candidates [com.bookcloud.iot.BookCloudApplication, com.bookcloud.iot.BookCloudApplicationWar] -> [Help 1]
BookCloudApplication.java
#Profile("!war")
#SpringBootApplication
#Import({SecurityConfig.class ,PersistenceConfig.class, ServiceConfig.class})
public class BookCloudApplication {
public static void main(String[] args) {
SpringApplication.run(BookCloudApplication.class, args);
}
}
BookCloudApplicationWar.java
#Profile("war")
#Import({SecurityConfig.class ,PersistenceConfig.class})
#SpringBootApplication
public class BookCloudApplicationWar extends SpringBootServletInitializer {
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(BookCloudApplicationWar.class);
}
public static void main(String[] args) throws Exception {
SpringApplication.run(BookCloudApplicationWar.class, args);
}
}

Answer 1

Maven profiles has no relation to Spring profiles.
You have two Maven profiles: jar, war
You either use:
mvn clean package -Pjar
or
mvn clean package -Pwar
The error you are getting is while building the artifact because pom needs:
<start-class>your.app.entry.point.Main</start-class>
inside the properties element.
I would suggest to have only one start class regardless of the Maven profile.
something like:
pom.xml:
...
<modelVersion>4.0.0</modelVersion>
<groupId>com.asimio.cloud</groupId>
<artifactId>zuul-server</artifactId>
<version>0-SNAPSHOT</version>
<packaging>${packaging.type}</packaging>
...
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<start-class>your.app.entry.point.Main</start-class>
<packaging.type>jar</packaging.type>
...
<profiles>
<profile>
<id>war</id>
<properties>
<packaging.type>war</packaging.type>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
</dependencies>
...
</profile>
</profiles>
...
Main.java:
package your.app.entry.point;
...
#SpringBootApplication
#Import({SecurityConfig.class ,PersistenceConfig.class, ServiceConfig.class})
public class App extends SpringBootServletInitializer {
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
return builder.sources(App.class);
}
public static void main(String[] args) {
SpringApplication.run(App.class, args);
}
}
No need for Spring profiles. This artifact can now be built using either Maven profile and will run either using:
java -jar .....
when building this artifact as a jar
or
as a war file deployed to a servlet container when built using the -Pwar Maven profile.

Answer 2

Maven profiles and Spring profiles are two different concepts.
You should also run Maven using the war profile, in order for the spring.boot.mainclass property to be set with the correct matching value.
Add -Pwar to the command line in order to activate the war Maven profile.
mvn clean package -DskipTests -Pwar -Dspring.profiles.active=pebloc,war -DAPPKEY=pebloc