如何在Maven插件中访问带有特定注解的类？

我想通过Maven插件访问项目中带有特定注解的类，现有代码如下：

@SuppressWarnings("unused")
@Parameter(defaultValue = "NotSet")
private String forecast;

@SuppressWarnings("unused")
@Parameter(defaultValue = "${project}")
private MavenProject mavenProject;

@Override
public void execute() throws MojoExecutionException, MojoFailureException {
    getLog().debug("Executing");
    // Accessing the maven project and getting the classes
    getLog().debug("Stopping");
}

尝试用Reflections库但无法作用于目标Maven项目，求解决思路。

解决方案 #

1. 配置@Mojo注解

给Mojo类添加注解配置，确保插件能获取到项目编译阶段的依赖：

@Mojo(name = "generator", defaultPhase = LifecyclePhase.COMPILE, requiresDependencyResolution = ResolutionScope.COMPILE)

2. 实现类路径加载与注解扫描

在execute方法中，通过MavenProject获取项目编译类路径，构建自定义类加载器后，传给Reflections完成注解扫描：

List<String> classpathElements = null;
try {
    classpathElements = mavenProject.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]));
    // 示例：加载指定类并打印其注解
    Class clazz = Class.forName("com.example.demo.DemoApplication", true, loader);
    Arrays.stream(clazz.getAnnotations())
            .forEach(System.out::println);
    // 使用Reflections扫描带有指定注解的类
    Reflections reflections = new Reflections(loader);
    reflections.getTypesAnnotatedWith(CuspidsApi.class)
            .forEach(System.out::println);
} catch (ClassNotFoundException e) {
    throw new MojoExecutionException(e.getMessage());
} catch (DependencyResolutionRequiredException e) {
    throw new MojoExecutionException("Dependency resolution failed", e);
}

内容的提问来源于stack exchange，提问作者DO QUOC VIET