In a Java annotation processor, I use DocTrees#getDocCommentTree(Element) to obtain a DocCommentTree, which I walk over with a visitor. Visitor's visitLink(LinkTree,C) method is invoked for found {@link tokens. For a {@link Foo}, LinkTree#getReference().getSignature() returns Foo, though it doesn't give you the fully-qualified class name. That is, is it java.lang.Foo? Is it Foo in the same package? Is it some Foo class imported? How can I get the fully qualified name of the reference while parsing links in Javadoc?
While parsing Javadoc in an annotation processor, we can first create an ImportTree and use it to determine the FQCN of a ReferenceTree returned by LinkTree#getReference(), that is, the FQCN in {@link signature label}. I have already implemented this for log4j-docgen in this commit. The pseudo-code is as follows:
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);
}
}
}
ImportTree hintImportTree in an annotation processor