Java : LSSerializer (XML) 示例

LSSerializer (Java SE 22 & JDK 22) 示例。
您将在大多数 LSSerializer 方法中找到代码示例。

注解 :

本文可能使用了翻译软件以方便阅读。另请查看英文原文。

简介

LSSerializer 提供用于将 DOM 文档序列化（写入）为 XML 的 API。XML 数据将写入字符串或输出流。序列化过程中所做的任何更改或修正都只会影响序列化的数据。序列化操作永远不会改变 Document 对象及其子对象。 (机器翻译)

Class diagram

final var xml = """
        <!DOCTYPE root [
            <!ENTITY aaa "bbb">
        ]>
        <root>&aaa;</root>
        """;

final var factory = DocumentBuilderFactory.newInstance();
factory.setExpandEntityReferences(false);

final var builder = factory.newDocumentBuilder();
final var document = builder.parse(new ByteArrayInputStream(xml.getBytes()));

final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {
    final var serializer = ls.createLSSerializer();
    final var str = serializer.writeToString(document);
    System.out.println(str);

    // Result
    // ↓
    //<?xml version="1.0" encoding="UTF-16"?><!DOCTYPE root [
    //<!ENTITY aaa 'bbb'>
    //]>
    //<root>&aaa;</root>
}

Methods

DOMConfiguration getDomConfig ()

LSSerializer 在序列化 DOM 节点时使用的 DOMConfiguration 对象。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {
    final var serializer = ls.createLSSerializer();
    final var domConfig = serializer.getDomConfig();

    final var names = domConfig.getParameterNames();
    for (int i = 0; i < names.getLength(); i++) {
        final var name = names.item(i);
        final var param = domConfig.getParameter(name);
        System.out.println(name + " : " + param);
    }

    // Result
    // ↓
    //canonical-form : false
    //cdata-sections : true
    //check-character-normalization : false
    //comments : true
    //datatype-normalization : false
    //element-content-whitespace : true
    //entities : true
    //infoset : false
    //namespaces : true
    //namespace-declarations : true
    //split-cdata-sections : true
    //validate : false
    //validate-if-schema : false
    //well-formed : true
    //discard-default-content : true
    //format-pretty-print : false
    //ignore-unknown-character-denormalizations : true
    //xml-declaration : true
    //http://www.oracle.com/xml/jaxp/properties/isStandalone : false
    //jdk.xml.isStandalone : false
    //error-handler : null
}

LSSerializerFilter getFilter ()

当应用程序提供过滤器时，序列化器将在序列化每个节点之前调用该过滤器。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {

    final var xml = """
            <root>
              <child><aaa/><bbb/><ccc/></child>
            </root>
            """;

    final var input = ls.createLSInput();
    input.setStringData(xml);

    final var parser = ls.createLSParser(DOMImplementationLS.MODE_SYNCHRONOUS, null);
    final var document = parser.parse(input);

    final var serializer = ls.createLSSerializer();
    System.out.println(serializer.getFilter()); // null

    //<?xml version="1.0" encoding="UTF-16"?><root>
    //  <child><aaa/><bbb/><ccc/></child>
    //</root>
    System.out.println(serializer.writeToString(document));

    final var filter = new LSSerializerFilter() {
        @Override
        public short acceptNode(Node n) {
            System.out.println("acceptNode : " + n);

            if (n.getNodeName().equals("bbb")) {
                return NodeFilter.FILTER_REJECT;
            } else {
                return NodeFilter.FILTER_ACCEPT;
            }
        }

        @Override
        public int getWhatToShow() {
            return NodeFilter.SHOW_ELEMENT;
        }
    };

    serializer.setFilter(filter);
    System.out.println(filter == serializer.getFilter()); // true

    System.out.println("-- write start --");

    final var ret = serializer.writeToString(document);

    System.out.println("-- write end --");
    System.out.println(ret);

    // Result
    // ↓
    //-- write start --
    //acceptNode : [root: null]
    //acceptNode : [child: null]
    //acceptNode : [aaa: null]
    //acceptNode : [aaa: null]
    //acceptNode : [bbb: null]
    //acceptNode : [bbb: null]
    //acceptNode : [ccc: null]
    //acceptNode : [ccc: null]
    //acceptNode : [child: null]
    //acceptNode : [root: null]
    //-- write end --
    //<?xml version="1.0" encoding="UTF-16"?><root>
    //  <child><aaa/><ccc/></child>
    //</root>
}

String getNewLine ()

正在写出的 XML 中要使用的行尾字符序列。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {
    final var serializer = ls.createLSSerializer();

    final var ret1 = serializer.getNewLine();
    System.out.println(Arrays.toString(ret1.getBytes())); // [10]
    System.out.println(ret1.equals("\n")); // true

    serializer.setNewLine("\r\n");

    final var ret2 = serializer.getNewLine();
    System.out.println(Arrays.toString(ret2.getBytes())); // [13, 10]
    System.out.println(ret2.equals("\r\n")); // true
}

void setFilter (LSSerializerFilter filter)

当应用程序提供过滤器时，序列化器将在序列化每个节点之前调用该过滤器。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {

    final var xml = """
            <root>
              <child><aaa/><bbb/><ccc/></child>
            </root>
            """;

    final var input = ls.createLSInput();
    input.setStringData(xml);

    final var parser = ls.createLSParser(DOMImplementationLS.MODE_SYNCHRONOUS, null);
    final var document = parser.parse(input);

    final var serializer = ls.createLSSerializer();
    System.out.println(serializer.getFilter()); // null

    //<?xml version="1.0" encoding="UTF-16"?><root>
    //  <child><aaa/><bbb/><ccc/></child>
    //</root>
    System.out.println(serializer.writeToString(document));

    final var filter = new LSSerializerFilter() {
        @Override
        public short acceptNode(Node n) {
            System.out.println("acceptNode : " + n);

            if (n.getNodeName().equals("bbb")) {
                return NodeFilter.FILTER_REJECT;
            } else {
                return NodeFilter.FILTER_ACCEPT;
            }
        }

        @Override
        public int getWhatToShow() {
            return NodeFilter.SHOW_ELEMENT;
        }
    };

    serializer.setFilter(filter);
    System.out.println(filter == serializer.getFilter()); // true

    System.out.println("-- write start --");

    final var ret = serializer.writeToString(document);

    System.out.println("-- write end --");
    System.out.println(ret);

    // Result
    // ↓
    //-- write start --
    //acceptNode : [root: null]
    //acceptNode : [child: null]
    //acceptNode : [aaa: null]
    //acceptNode : [aaa: null]
    //acceptNode : [bbb: null]
    //acceptNode : [bbb: null]
    //acceptNode : [ccc: null]
    //acceptNode : [ccc: null]
    //acceptNode : [child: null]
    //acceptNode : [root: null]
    //-- write end --
    //<?xml version="1.0" encoding="UTF-16"?><root>
    //  <child><aaa/><ccc/></child>
    //</root>
}

void setNewLine (String newLine)

正在写出的 XML 中要使用的行尾字符序列。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {
    final var serializer = ls.createLSSerializer();

    final var ret1 = serializer.getNewLine();
    System.out.println(Arrays.toString(ret1.getBytes())); // [10]
    System.out.println(ret1.equals("\n")); // true

    serializer.setNewLine("\r\n");

    final var ret2 = serializer.getNewLine();
    System.out.println(Arrays.toString(ret2.getBytes())); // [13, 10]
    System.out.println(ret2.equals("\r\n")); // true
}

boolean write (Node nodeArg, LSOutput destination)

按照上面 LSSerializer 接口的一般描述序列化指定的节点。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {

    final var document = builder.newDocument();

    final var root = document.createElement("root");
    document.appendChild(root);

    final var text = document.createTextNode("abcd");
    root.appendChild(text);

    final var path = Path.of("R:", "java-work", "sample.xml");
    System.out.println(path); // R:\java-work\sample.xml

    try (final var writer = Files.newBufferedWriter(path)) {

        final var destination = ls.createLSOutput();
        destination.setCharacterStream(writer);

        final var serializer = ls.createLSSerializer();

        final var ret = serializer.write(document, destination);
        System.out.println(ret); // true
    }

    //<?xml version="1.0" encoding="UTF-8"?><root>abcd</root>
    System.out.println(Files.readString(path));
}

String writeToString (Node nodeArg)

按照上面 LSSerializer 接口的一般描述序列化指定的节点。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {

    final var document = builder.newDocument();

    final var root = document.createElement("root");
    document.appendChild(root);

    final var text = document.createTextNode("abcd");
    root.appendChild(text);

    final var serializer = ls.createLSSerializer();
    final var str = serializer.writeToString(document);

    //<?xml version="1.0" encoding="UTF-16"?><root>abcd</root>
    System.out.println(str);
}

boolean writeToURI (Node nodeArg, String uri)

一种便捷方法，其作用就像使用未指定编码的 LSOutput 调用 LSSerializer.write 并将 LSOutput.systemId 设置为 uri 参数一样。 (机器翻译)

final var factory = DocumentBuilderFactory.newInstance();
final var builder = factory.newDocumentBuilder();
final var domImpl = builder.getDOMImplementation();

final var feature = domImpl.getFeature("LS", "3.0");
if (feature instanceof DOMImplementationLS ls) {

    final var document = builder.newDocument();

    final var root = document.createElement("root");
    document.appendChild(root);

    final var text = document.createTextNode("abcd");
    root.appendChild(text);

    final var path = Path.of("R:", "java-work", "sample.xml");
    System.out.println(path); // R:\java-work\sample.xml

    final var uri = path.toUri();
    System.out.println(uri); // file:///R:/java-work/sample.xml

    final var serializer = ls.createLSSerializer();

    final var ret = serializer.writeToURI(document, uri.toString());
    System.out.println(ret); // true

    //<?xml version="1.0" encoding="UTF-8"?><root>abcd</root>
    System.out.println(Files.readString(path));
}

API 示例

Java : LSSerializer (XML) 示例

简介

Methods

DOMConfiguration getDomConfig ()

LSSerializerFilter getFilter ()

String getNewLine ()

void setFilter (LSSerializerFilter filter)

void setNewLine (String newLine)

boolean write (Node nodeArg, LSOutput destination)

String writeToString (Node nodeArg)

boolean writeToURI (Node nodeArg, String uri)

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