Spring Boot with POM packaging Agregator

问题

Is it possible to use Spring Boots Maven plugin command spring-boot:run when the parent POM of the project is using packaging mode POM because of its children?

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I have multi module maven project with a "master" POM that is in it's turn a child of the Spring Boot Parent module. Looking something like this:

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>project</artifactId>
    <packaging>pom</packaging>
    <version>0.1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.0.BUILD-SNAPSHOT</version>
        <relativePath/>
    </parent>

    <modules>
        <module>module1</module>
        <module>module2</module>
        <module>module3</module>
    </modules>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <start-class>com.example.module1.Application</start-class>
        <java.version>1.8</java.version>
    </properties>

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

This is basically our "master" POM which every child uses as it's parent. Now we want to perform the spring-boot:run command from the working directory this "master" POM is in. Problem is, this generates a ClassNotFoundException which is odd since module1 (where this Application class is located) is included in the POM and mentioned as a module.

Using a single module maven project and <packaging>jar</packaging> this compiles and runs the Application class so it is not Spring-Boot that is not working right here.

What do I have to change to get this working or is it simply not possible to use the spring-boot-maven-plugin plugin when dealing with multi module Maven projects?

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Sidenote: My Application class / Module 1 has the other modules as dependencies so keep this in mind when answering the question. Any suggestions on how to improve this are very appreciated.

回答1:

It is not possible, as far as I know, because the plugin requires an executable jar to run.

The docs for the spring-boot plugin goal "run" says:

Description

Run an executable archive application

Packaging pom is will not create an executable. It will only generate a pom.xml.

Try to run mvn install and look at the artifact deployed to your local repository:

I just did for a module I have with packaging pom:

[INFO] Installing C:\projects\boot-parent\pom.xml to 
C:\Users\...\repository\no\boot-parent\0.0.1-SNAPSHOT\boot-parent-0.0.1-SNAPSHOT.pom

As you can see the artifact is boot-parent-0.0.1-SNAPSHOT.pom.

Try putting the plugin-configuration in the pom for module1 which has the start-class (main-class) and has packaging jar.

Edit for your comment:

Your comment suggests that you have issues with your client side Maven installation. Have a look at this answer. And especially the answer given by @ChristianAchilli.

I use to solve this issue by deleting the corresponding failed to download artifact directory in my local repo. Next time I run the maven command the artifact download is triggered again. Therefore I'd say it's a client side setting.

Again, hope this helps!

Thomas

回答2:

Make one module more where is only your Application inside. If you insert dependencies to your modules you can start your module normal with spring-boot:run or export as jar.

See your parent only as container.

Hope that work for you

来源：https://stackoverflow.com/questions/27297308/spring-boot-with-pom-packaging-agregator