java - 来自 Maven Mojo 的思考

Question

我想使用 Google Reflections 从我的 Maven 插件编译的项目中扫描类。但是默认情况下插件看不到项目的编译类。来自 Maven 3 documentation我阅读:

Plugins that need to load classes from the compile/runtime/test class path of a project need to create a custom URLClassLoader in combination with the mojo annotation @requiresDependencyResolution.

至少可以说这有点含糊。基本上我需要一个类加载器的引用来加载已编译的项目类。我如何获得它？

编辑:

好的，@Mojo 注释有 requiresDependencyResolution 参数，所以这很简单，但仍然需要正确的方法来构建类加载器。

Answer 1

@Component
private MavenProject project;

@SuppressWarnings("unchecked")
@Override
public void execute() throws MojoExecutionException {
    List<String> classpathElements = null;
    try {
        classpathElements = project.getCompileClasspathElements();
        List<URL> projectClasspathList = new ArrayList<URL>();
        for (String element : classpathElements) {
            try {
                projectClasspathList.add(new File(element).toURI().toURL());
            } catch (MalformedURLException e) {
                throw new MojoExecutionException(element + " is an invalid classpath element", e);
            }
        }

        URLClassLoader loader = new URLClassLoader(projectClasspathList.toArray(new URL[0]));
        // ... and now you can pass the above classloader to Reflections

    } catch (ClassNotFoundException e) {
        throw new MojoExecutionException(e.getMessage());
    } catch (DependencyResolutionRequiredException e) {
        new MojoExecutionException("Dependency resolution failed", e);
    }
}