Circular Dependencies in Eclipse Platform

问题

I'm trying to add the Eclipse Platform to my Maven project and stumbled over something very weird.

There is the plug-in org.eclipse.swt, which has a dependency org.eclipse.swt.${osgi.platform}, where ${osgi.platform} can be any of the following:

• cocoa.macosc.cocoa
• gtk.linux.aarch64
• win32.win32.x86_64

However if you check the pom.xml of org.eclipse.swt.win32.win32.x86_64 you learn that this project has a dependency to org.eclipse.swt. Which forms a nice dependency circle, which is not allowed in Maven nor in OSGi.

Consequently I'm getting a StackOverflowError, but only if I try to use the maven-dependency-plugin with -Dosgi.platform=win32.win32.x86_64.

If I don't use that parameter I get the following exception:

No versions available for org.eclipse.platform:org.eclipse.swt.gtk.linux.aarch64:jar:[3.105.2,3.105.2]

(Which is probably okay, because I guess that Linux is the default value, but it doesn't apply to me, since I've got a Windows PC.)

I can't exclude the dependency either, e.g. with:

        <dependency>
            <groupId>org.eclipse.platform</groupId>
            <artifactId>org.eclipse.swt</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.eclipse.platform</groupId>
                    <artifactId>org.eclipse.swt.gtk.linux.aarch64</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

I get the same error messages as above with that approach.

I'm wondering how the Eclipse guys even managed to release that mess, but more importantly: How do I build against a Maven project with circular dependencies like this?

回答1:

You're looking at the wrong place. Eclipse artifacts are published in Eclipse p2 repositories. In addition, some Eclipse artifacts will be published in Maven repositories for use in plain (non-Eclipse based) Java applications which cannot be used to build Eclipse-based applications. Something seems to have gone wrong publishing Eclipse SWT to Maven Central causing the circular dependencies. Please report this to Eclipse.

The Eclipse IDE packages are built with the Maven plug-in Tycho. See for example the pom.xml file for the Eclipse platform or here the parent pom.xml for all IDE packages. Tycho uses one or more Eclipse p2 repositories to resolve dependencies. A Maven repository would not work to resolve Import-Package dependencies or product configurations, for example. In a Maven repository, an artifact has a version, while in a p2 repository also Java packages of the same JAR can have different versions. In a Maven Tycho pom.xml only the p2 repositories have to be specified, the dependencies are already declared in the META-INF/MANIFEST.MF, feature.xml and *.product files.

来源：https://stackoverflow.com/questions/54092774/circular-dependencies-in-eclipse-platform