如何在Maven中继承Web应用程序的Java-EE API？

Question

My project has the following structure with multiple jars and wars:

root (pom)
+--core (jar)
+--webapp (jar)
+--childgroup (pom)
   +--actual-web-application (war)
   +--some-library (jar)
+--othergroup (pom)
   +--another-web-application (war)       

Where actual-web-application depends on webapp which depends on core. Ideally, I would like to specify the Java EE dependency only in the webapp module and let the actual-web-application inherit it. But because it's a provided dependency, this doesn't work and I have to manually add dependencies for provided stuff like Java EE, jax-rs etc. in every web application.

Is there any way, with dependencyManagement for example, to let actual-web-application inherit the javaee-api from the webapp?

What I've tried, in webapp's pom.xml:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
        </dependency>
    </dependencies>
</dependencyManagement>

And in actual-web-application's pom.xml:

   <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <scope>provided</scope>
    </dependency>

However, it complies about the version so it seems like it's still not carrying over the dependency from webapp's pom.xml.

Answer 1

也将<scope>provided</scope>放入dependencyManagement

Answer 2

Provided dependencies are inherited just as any other dependency would be.

parent pom.xml:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

child pom.xml:

<dependencies>
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
    </dependency>
</dependencies>

And the child's dependency tree:

--- maven-dependency-plugin:2.8:tree (default-cli) @ child ---
com.iei.web:child:war:1.0-SNAPSHOT
\- javax:javaee-api:jar:7.0:provided
   \- com.sun.mail:javax.mail:jar:1.5.0:provided
       \- javax.activation:activation:jar:1.1:provided

If you are trying to avoid explicitly defining dependencies in the child at all, then you would of course have to move it out of dependencyManagement in the parent and make it a direct dependency, assuming you want every child module to inherit it.

Dependency Management