How do I tell Spring Boot which main class to use for the executable jar?

Execution default of goal 
org.springframework.boot:spring-boot-maven-plugin:1.0.1.RELEASE:repackage 
failed: 
Unable to find a single main class from the following candidates

My project has more than one class with a main method. How do I tell the Spring Boot Maven plugin which of the classes it should use as the main class?

ludo_rj

Add your start class in your pom:

<properties>
    <!-- The main class to start by executing java -jar -->
    <start-class>com.mycorp.starter.HelloWorldApplication</start-class>
</properties>

<build>
<plugins>
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>             
        <configuration>    
            <mainClass>com.mycorp.starter.HelloWorldApplication</mainClass>
        </configuration>
    </plugin>
</plugins>
</build>

For those using Gradle (instead of Maven) :

springBoot {
    mainClass = "com.example.Main"
}

If you do NOT use the spring-boot-starter-parent pom, then from the Spring documentation:

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>1.1.3.RELEASE</version>
    <configuration>
        <mainClass>my.package.MyStartClass</mainClass>
        <layout>ZIP</layout>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
        </execution>
    </executions>
</plugin>

For those using Gradle (instead of Maven), referencing here:

The main class can also be configured explicitly using the task’s mainClassName property:

bootJar {
    mainClassName = 'com.example.ExampleApplication'
}

Alternatively, the main class name can be configured project-wide using the mainClassName property of the Spring Boot DSL:

springBoot {
    mainClassName = 'com.example.ExampleApplication'
}

mojave

If you're using spring-boot-starter-parent in your pom, you simply add the following to your pom:

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

Then do your mvn package.

See this Spring docs page.

A very important aspect here is to mention that the directory structure has to be src/main/java/nameofyourpackage

I tried the following code in pom.xml and it worked for me

<build>
<plugins>
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <configuration>
            <mainClass>myPackage.HelloWorld</mainClass> 
        </configuration>
    </plugin>
    <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
            <fork>true</fork>
            <executable>D:\jdk1.8\bin\javaw.exe</executable>
        </configuration>
    </plugin>
</plugins>

I had renamed my project and it was still finding the old Application class on the build path. I removed it in the 'build' folder and all was fine.

tan9

Since Spring Boot 1.5, you can complete ignore the error-prone string literal in pom or build.gradle. The repackaging tool (via maven or gradle plugin) will pick the one annotated with @SpringBootApplication for you. (Refer to this issue for detail: https://github.com/spring-projects/spring-boot/issues/6496 )

Have seen this issue with Java 1.9 and SpringBoot 1.5.x, when main-class is not specified explicitly.

With Java 1.8, it is able to find main-class without explicit property and 'mvn package' works fine.

来源：https://stackoverflow.com/questions/23217002/how-do-i-tell-spring-boot-which-main-class-to-use-for-the-executable-jar

标签

java

Spring

maven

executable-jar

spring-boot