解析 Javadoc 时链接的完全限定类名

Question

在 Java 注释处理器中，我使用

DocTrees#getDocCommentTree(Element)

来获取

DocCommentTree

，我与访客一起走过它。为找到的 visitLink(LinkTree,C)

 令牌调用

访问者的 {@link

 方法

。对于

{@link Foo}

，

LinkTree#getReference().getSignature()

返回

Foo

，尽管它不会提供完全限定的类名。也就是说，是

java.lang.Foo

吗？是

Foo

在同一个包裹里吗？是导入了一些

Foo

类吗？在解析 Javadoc 中的链接时如何获取参考文献的完全限定名称？

Answer 1

在注释处理器中解析Javadoc时，我们可以首先创建一个

ImportTree

，并用它来确定

ReferenceTree

返回的

LinkTree#getReference()

的FQCN，即

{@link signature label}

中的FQCN。我已经在

this commit

中为 log4j-docgen 实现了这个。伪代码如下：

public class ExampleProcessor extends AbstractProcessor {

    private DocTrees docTrees;

    private Trees trees;

    @Override
    public synchronized void init(final ProcessingEnvironment processingEnv) {
        super.init(processingEnv);
        docTrees = DocTrees.instance(processingEnv);
        trees = Trees.instance(processingEnv);
    }

    private void scanDocTree(Element element) {
        Map<String, String> imports = collectElementImports(element);
        ExampleContext context = new ExampleContext(imports);
        DocCommentTree tree = docTrees.getDocCommentTree(element);
        ExampleDocTreeVisitor visitor = new ExampleDocTreeVisitor();
        tree.accept(visitor, context);
    }

    private static final class ExampleDocTreeVisitor<Void, ExampleContext>
            extends SimpleDocTreeVisitor<Void, ExampleContext> {

        @Override
        public Void visitLink(LinkTree linkTree, final ExampleContext context) {
            String signature = linkTree.getReference().getSignature();
            String fqcn = context.imports.get(signature);
            // ...
            return super.visitLink(node, data);
        }

    }

    private Map<String, String> collectElementImports(Element element) {
        ImportCollectingTreeScanner scanner = new ImportCollectingTreeScanner();
        TreePath treePath = trees.getPath(element);
        scanner.scan(treePath.getCompilationUnit(), null);
        return scanner.imports;
    }

    private static final class ImportCollectingScanner
            extends TreeScanner<Object, Trees> {

        private final Map<String, String> imports = new HashMap<>();

        @Override
        public Object visitImport(ImportTree importTree, Trees trees) {
            Tree qualifiedIdentifier = importTree.getQualifiedIdentifier();
            String qualifiedClassName = qualifiedIdentifier.toString();
            String simpleClassName = qualifiedClassName.substring(qualifiedClassName.lastIndexOf('.') + 1);
            imports.put(simpleClassName, qualifiedClassName);
            return super.visitImport(importTree, trees);
        }

    }

}

学分

• @piotr-p-karwasz 获取

  ImportTree

  提示
• Andi 的博客，介绍如何在注释处理器中提取

  ImportTree