很多人正在使用JavaParser实现最不同的目标。 其中之一是提取文档。 在这篇简短的文章中，我们将看到如何打印与类或接口关联的所有JavaDoc注释。
可以在GitHub上找到代码： https : //github.com/ftomassetti/javadoc-extractor
获取类的所有Javadoc注释我们正在重用DirExplorer，在提出了支持类的介绍JavaParser类 。 此类允许递归处理目录，解析其中包含的所有Java文件。
我们可以从遍历所有类开始，然后找到相关的Javadoc注释。
/** * Iterate over the classes and print their Javadoc. */public class ClassesJavadocExtractor { public static void main(String[] args) { File projectDir = new File("source_to_parse/"); new DirExplorer((level, path, file) -> path.endsWith(".java"), (level, path, file) -> { try { new VoidVisitorAdapter<Object>() { @Override public void visit(ClassOrInterfaceDeclaration n, Object arg) { super.visit(n, arg); if (n.getComment() != null && n.getComment() instanceof JavadocComment) { String title = String.format("%s (%s)", n.getName(), path); System.out.println(title); System.out.println(Strings.repeat("=", title.length())); System.out.println(n.getComment()); } } }.visit(JavaParser.parse(file), null); } catch (IOException e) { new RuntimeException(e); } }).explore(projectDir); } }如您所见，获取JavaDoc注释非常容易。 它产生以下结果：
ASTParserConstants (/javaparser/javaparser-core/target/generated-sources/javacc/com/github/javaparser/ASTParserConstants.java)==============================================================================================================================/** * Token literal values and constants. * Generated by org.javacc.parser.OtherFilesGen#start() */ ParseException (/javaparser/javaparser-core/target/generated-sources/javacc/com/github/javaparser/ParseException.java)======================================================================================================================/** * This exception is thrown when parse errors are encountered. * You can explicitly create objects of this exception type by * calling the method generateParseException in the generated * parser. * * You can modify this class to customize your error reporting * mechanisms so long as you retain the public fields. */ ASTParser (/javaparser/javaparser-core/target/generated-sources/javacc/com/github/javaparser/ASTParser.java)============================================================================================================/** *This class was generated automatically by javacc, do not edit.*/ ASTParserTokenManager (/javaparser/javaparser-core/target/generated-sources/javacc/com/github/javaparser/ASTParserTokenManager.java) ==================================================================================================================================== /** Token Manager. */ 获取所有Javadoc注释并找到记录的元素在其他情况下，我们可能要开始收集所有Javadoc注释，然后找到要注释的元素。 我们也可以使用Javaparser轻松做到这一点：
/** * Iterate over all the Javadoc comments and print them together with a description of the commented element. */public class AllJavadocExtractor { public static void main(String[] args) { File projectDir = new File("source_to_parse/"); new DirExplorer((level, path, file) -> path.endsWith(".java"), (level, path, file) -> { try { new VoidVisitorAdapter<Object>() { @Override public void visit(JavadocComment comment, Object arg) { super.visit(comment, arg); String title = null; if (comment.getCommentedNode().isPresent()) { title = String.format("%s (%s)", describe(comment.getCommentedNode().get()), path); } else { title = String.format("No element associated (%s)", path); } System.out.println(title); System.out.println(Strings.repeat("=", title.length())); System.out.println(comment); } }.visit(JavaParser.parse(file), null); } catch (IOException e) { new RuntimeException(e); } }).explore(projectDir); } private static String describe(Node node) { if (node instanceof MethodDeclaration) { MethodDeclaration methodDeclaration = (MethodDeclaration)node; return "Method " + methodDeclaration.getDeclarationAsString(); } if (node instanceof ConstructorDeclaration) { ConstructorDeclaration constructorDeclaration = (ConstructorDeclaration)node; return "Constructor " + constructorDeclaration.getDeclarationAsString(); } if (node instanceof ClassOrInterfaceDeclaration) { ClassOrInterfaceDeclaration classOrInterfaceDeclaration = (ClassOrInterfaceDeclaration)node; if (classOrInterfaceDeclaration.isInterface()) { return "Interface " + classOrInterfaceDeclaration.getName(); } else { return "Class " + classOrInterfaceDeclaration.getName(); } } if (node instanceof EnumDeclaration) { EnumDeclaration enumDeclaration = (EnumDeclaration)node; return "Enum " + enumDeclaration.getName(); } if (node instanceof FieldDeclaration) { FieldDeclaration fieldDeclaration = (FieldDeclaration)node; List<String> varNames = fieldDeclaration.getVariables().stream().map(v -> v.getName().getId()).collect(Collectors.toList()); return "Field " + String.join(", ", varNames); } return node.toString(); } }在这里，大多数代码都是关于为注释节点提供描述的（方法describe ）。
结论操作AST并找到Javadoc注释非常容易。 但是，缺少的一项功能是可以以结构化形式提取Javadoc中包含的信息。 例如，您可能只想获取与某个参数或返回值关联的Javadoc部分。 Javaparser当前不具有此功能，但是我正在研究此功能，应该在接下来的1-2周内将其合并。 如果要关注开发，请查看问题433 。
感谢您的阅读和愉快的解析！
翻译自: https://www.javacodegeeks.com/2017/01/extracting-javadoc-documentation-source-files-using-javaparser.html