如何转换一个简单的方法来返回列表＆lt; string＆gt;将元＆gt;基于Smallrye Mutiny？

Question

我正在开发一个应用程序，该应用程序读取XML文件并根据XML中存在的详细信息创建哈希ID。截至目前，一切都可以完美地工作，并且能够获得list＆lt; string＆gt;。

我想使用Smallrye Mutiny将此应用程序转换为反应流，因此我浏览了一些文档，但不明确地了解如何将此应用程序转换为>反应流我不必等待所有XML文件的完成才能返回list＆lt; string＆gt;。相反，我可以在生成时开始返回multi＆lt; string＆gt;。

以下是我正在使用SAX解析器来创建哈希ID的简单XML：

<customerList>
    <customer>
        <name>Batman</name>
        <age>25</age>
    </customer>
    <customer>
        <name>Superman</name>
        <age>28</age>
    </customer>
</customerList>

以下是主要应用程序，它将调用saxhandler：

public Multi<String> xmlEventHashGenerator(final InputStream xmlStream) throws SAXException, ParserConfigurationException, IOException {
    final SAXParserFactory factory = SAXParserFactory.newInstance();
    final SaxHandler saxHandler = new SaxHandler();
    factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
    factory.newSAXParser().parse(xmlStream, saxHandler);

    return Multi.createFrom().emitter(em ->{
        saxHandler.getRootNodes().forEach(contextNode -> {
            final String preHashString = contextNode.toString();
            try {
                final StringBuilder hashId = new StringBuilder();
                MessageDigest.getInstance("SHA-256").digest(preHashString.getBytes(StandardCharsets.UTF_8));
                hashId.append(DatatypeConverter.printHexBinary(digest).toLowerCase());
                em.emit(hashId.toString());
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
            }
        });
        em.complete();
    });
}

以下是saxhandler将读取XML并创建Hashids：

public class SaxHandler extends DefaultHandler {
    @Getter
    private final List<String> eventHashIds = new ArrayList<>();
    @Getter
    private final List<ContextNode> rootNodes = new ArrayList<>();

    private final HashMap<String, String> contextHeader = new HashMap<>();
    private final String hashAlgorithm;
    private ContextNode currentNode = null;
    private ContextNode rootNode = null;
    private final StringBuilder currentValue = new StringBuilder();

    public SaxHandler(final String hashAlgorithm) {
        this.hashAlgorithm = hashAlgorithm;
    }

    @Override
    public void startElement(final String uri, final String localName, final String qName, final Attributes attributes) {
        if (rootNode == null && qName.equals("customer")) {
            rootNode = new ContextNode(contextHeader);
            currentNode = rootNode;
            rootNode.children.add(new ContextNode(rootNode, "type", qName));
        }else if (currentNode != null) {
            ContextNode n = new ContextNode(currentNode, qName, (String) null);
            currentNode.children.add(n);
            currentNode = n;
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) {
        currentValue.append(ch, start, length);
    }

    @Override
    public void endElement(final String uri, final String localName, final String qName) {

        if (rootNode != null && !qName.equals("customer")) {
            final String value = !currentValue.toString().trim().equals("") ? currentValue.toString().trim() : null;
            currentNode.children.add(new ContextNode(currentNode, qName, value));
        }

        if (qName.equals("customer")) {
            rootNodes.add(rootNode);
            rootNode = null;
        }
        currentValue.setLength(0);
    }
}

以下是test：

@Test
    public void xmlTest() throws Exception {
        final HashGenerator eventHashGenerator = new HashGenerator();
        final InputStream xmlStream = getClass().getResourceAsStream("/customer.xml");
        final List<String> eventHashIds = eventHashGenerator.xmlHashGenerator(xmlStream, "sha3-256");
        System.out.println("\nGenerated Event Hash Ids : \n" + eventHashIds);
    }

有人可以指导我参加一些示例或提供有关如何将此应用程序转换为smallye mutinty mutinty multi＆lt; string＆gt; 基于应用程序？

Answer 1

我认为您可以重构xmleventhashgenerator对

    public Multi<String> xmlEventHashGenerator(final InputStream xmlStream) throws SAXException, ParserConfigurationException, IOException {
        final SAXParserFactory factory = SAXParserFactory.newInstance();
        final SaxHandler saxHandler = new SaxHandler();
        factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
        factory.newSAXParser().parse(xmlStream, saxHandler);

        return Multi.createFrom()
                .iterable( saxHandler.getRootNodes() )
                .map( RootNode::toString )
                .map( this::convertDatatype );
    }

    private String convertDatatype(String preHashString) {
        try {
            // I think we could create the MessageDigest instance only once
            byte[] digest = MessageDigest.getInstance( "SHA-256" )
                    .digest( preHashString.getBytes( StandardCharsets.UTF_8 ) );
            return DatatypeConverter.printHexBinary( digest ).toLowerCase();
        }
        catch (NoSuchAlgorithmException e) {
            throw new IllegalArgumentException( e );
        }
    }

方法看起来像：

    @Test
    public void xmlTest() throws Exception {
        final HashGenerator eventHashGenerator = new HashGenerator();
        final InputStream xmlStream = getClass().getResourceAsStream("/customer.xml");
        System.out.println("Generated Event Hash Ids: ");
        eventHashGenerator
            .xmlHashGenerator(xmlStream)
            // Print all the hash codes
            .invoke( hash -> System.out.println( hash )
            .await().indefinitely();
     }

测试

    @Test
    public void xmlTest() throws Exception {
        final HashGenerator eventHashGenerator = new HashGenerator();
        final InputStream xmlStream = getClass()
            .getResourceAsStream("/customer.xml");
        String hash = eventHashGenerator
            .xmlHashGenerator(xmlStream)
            // Concatenate all the results
            .collect().with( Collectors.joining() );
            // Print the hashcode
            .invoke( hashcode -> System.out.println("\nGenerated Event Hash Ids : \n" + hashcode) )
            .await().indefinitely();
     }