Java : Transformer (XML) 示例

Transformer (Java SE 22 & JDK 22) 示例。
您将在大多数 Transformer 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

这个抽象类的实例可以将源树转换为结果树。 (机器翻译)

Class diagram

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
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 factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer();

final var source = new DOMSource(document);
final var result = new StreamResult(new StringWriter());
transformer.transform(source, result);

//<?xml version="1.0" encoding="UTF-8" standalone="no"?><root>abcd</root>
System.out.println(result.getWriter());

Constructors

Transformer ()

默认构造函数是故意保护的。 (机器翻译)

protected. I think it's rare to create a subclass of this class. Therefore, the code example is omitted.

Methods

abstract void clearParameters ()

清除所有用 setParameter 设置的参数。 (机器翻译)

final var xml = """
        <root/>
        """;

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

final var xsl = """
        <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
          <xsl:output omit-xml-declaration="yes" />
          <xsl:param name="param">aaaa</xsl:param>

          <xsl:template match="root">
            <xsl:copy-of select="$param" />
          </xsl:template>

        </xsl:stylesheet>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer(
        new StreamSource(new ByteArrayInputStream(xsl.getBytes())));

System.out.println(transformer.getParameter("param")); // null
transformer.setParameter("param", "bbbb");

{
    System.out.println(transformer.getParameter("param")); // bbbb

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //bbbb
    System.out.println(result.getWriter());
}

transformer.clearParameters();

{
    System.out.println(transformer.getParameter("param")); // null

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //aaaa
    System.out.println(result.getWriter());
}

abstract ErrorListener getErrorListener ()

获取转换中有效的错误事件处理程序。 (机器翻译)

// An XML text with incorrect syntax.
final var xml = """
        <root>
            <<<child>aaa</child>
        </root>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer();

final var listener = new ErrorListener() {
    @Override
    public void warning(TransformerException exception) {
        System.out.println("-- ErrorListener warning --");
        System.out.println(exception);
    }

    @Override
    public void error(TransformerException exception) {
        System.out.println("-- ErrorListener error --");
        System.out.println(exception);
    }

    @Override
    public void fatalError(TransformerException exception) {
        System.out.println("-- ErrorListener fatalError --");
        System.out.println(exception);
    }
};

transformer.setErrorListener(listener);
System.out.println(listener == transformer.getErrorListener()); // true

final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
final var result = new StreamResult(new StringWriter());

try {
    transformer.transform(source, result);
} catch (TransformerException e) {
    System.out.println("-- TransformerException --");
    System.out.println(e);
}

// Result
// ↓
//-- ErrorListener error --
//javax.xml.transform.TransformerException:
// The content of elements must consist of well-formed character data or markup.
//-- TransformerException --
//javax.xml.transform.TransformerException:
// org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 6;
// The content of elements must consist of well-formed character data or markup.

abstract Properties getOutputProperties ()

获取转换的输出属性的副本。 (机器翻译)

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

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

final var transformer = TransformerFactory.newInstance().newTransformer();

{
    final var ret = transformer.getOutputProperties();
    System.out.println(ret.size()); // 0

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<?xml version="1.0" encoding="UTF-8" standalone="no"?><root><child>aaa</child></root>
    System.out.println(result.getWriter());
}

final var properties = new Properties();
properties.setProperty(OutputKeys.INDENT, "yes");
properties.setProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

transformer.setOutputProperties(properties);

{
    final var ret = transformer.getOutputProperties();
    System.out.println(ret); // {indent=yes, omit-xml-declaration=yes}

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>
    //    <child>aaa</child>
    //</root>
    System.out.println(result.getWriter());
}

abstract String getOutputProperty (String name)

获取对变压器有效的输出属性。 (机器翻译)

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

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

final var transformer = TransformerFactory.newInstance().newTransformer();

{
    final var ret1 = transformer.getOutputProperty(OutputKeys.INDENT);
    System.out.println(ret1); // "no"

    final var ret2 = transformer.getOutputProperty(OutputKeys.OMIT_XML_DECLARATION);
    System.out.println(ret2); // "no"

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<?xml version="1.0" encoding="UTF-8" standalone="no"?><root><child>aaa</child></root>
    System.out.println(result.getWriter());
}

transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

{
    final var ret1 = transformer.getOutputProperty(OutputKeys.INDENT);
    System.out.println(ret1); // "yes"

    final var ret2 = transformer.getOutputProperty(OutputKeys.OMIT_XML_DECLARATION);
    System.out.println(ret2); // "yes"

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>
    //    <child>aaa</child>
    //</root>
    System.out.println(result.getWriter());
}

abstract Object getParameter (String name)

获取使用 setParameter 明确设置的参数。 (机器翻译)

final var xml = """
        <root/>
        """;

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

final var xsl = """
        <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
          <xsl:output omit-xml-declaration="yes" />
          <xsl:param name="param">aaaa</xsl:param>

          <xsl:template match="root">
            <xsl:copy-of select="$param" />
          </xsl:template>

        </xsl:stylesheet>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer(
        new StreamSource(new ByteArrayInputStream(xsl.getBytes())));

System.out.println(transformer.getParameter("param")); // null
transformer.setParameter("param", "bbbb");

{
    System.out.println(transformer.getParameter("param")); // bbbb

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //bbbb
    System.out.println(result.getWriter());
}

transformer.clearParameters();

{
    System.out.println(transformer.getParameter("param")); // null

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //aaaa
    System.out.println(result.getWriter());
}

abstract URIResolver getURIResolver ()

获取用于解析 document() 中使用的 URI 的对象。 (机器翻译)

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

Files.writeString(sampleA, """
        <root>aaa</root>
        """);

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

Files.writeString(sampleB, """
        <root>bbb</root>
        """);

final var xml = """
        <root/>
        """;

final var xsl = """
        <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
          <xsl:output omit-xml-declaration="yes" />
          <xsl:variable name="doc" select="document('file:///R:/java-work/sample-a.xml')" />

          <xsl:template match="/">
            <xsl:copy-of select="$doc" />
          </xsl:template>

        </xsl:stylesheet>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer(
        new StreamSource(new ByteArrayInputStream(xsl.getBytes())));

{
    System.out.println(transformer.getURIResolver()); // null

    final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>aaa</root>
    System.out.println(result.getWriter());
}

final var urlResolver = new URIResolver() {
    @Override
    public Source resolve(String href, String base) {
        if ("file:///R:/java-work/sample-a.xml".equals(href)) {
            return new StreamSource("file:///R:/java-work/sample-b.xml");
        }

        return null;
    }
};

transformer.setURIResolver(urlResolver);

{
    System.out.println(transformer.getURIResolver() == urlResolver); // true

    final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>bbb</root>
    System.out.println(result.getWriter());
}

void reset ()

将此变压器重置为其原始配置。 (机器翻译)

final var transformer = TransformerFactory.newInstance().newTransformer();

transformer.setParameter("param", "bbbb");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

System.out.println(transformer.getParameter("param")); // "bbbb"
System.out.println(transformer.getOutputProperty(OutputKeys.INDENT)); // "yes"
System.out.println(transformer.getOutputProperty(OutputKeys.OMIT_XML_DECLARATION)); // "yes"

transformer.reset();

System.out.println(transformer.getParameter("param")); // null
System.out.println(transformer.getOutputProperty(OutputKeys.INDENT)); // "no"
System.out.println(transformer.getOutputProperty(OutputKeys.OMIT_XML_DECLARATION)); // "no"

abstract void setErrorListener (ErrorListener listener)

设置转换过程中有效的错误事件监听器。 (机器翻译)

// An XML text with incorrect syntax.
final var xml = """
        <root>
            <<<child>aaa</child>
        </root>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer();

final var listener = new ErrorListener() {
    @Override
    public void warning(TransformerException exception) {
        System.out.println("-- ErrorListener warning --");
        System.out.println(exception);
    }

    @Override
    public void error(TransformerException exception) {
        System.out.println("-- ErrorListener error --");
        System.out.println(exception);
    }

    @Override
    public void fatalError(TransformerException exception) {
        System.out.println("-- ErrorListener fatalError --");
        System.out.println(exception);
    }
};

transformer.setErrorListener(listener);
System.out.println(listener == transformer.getErrorListener()); // true

final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
final var result = new StreamResult(new StringWriter());

try {
    transformer.transform(source, result);
} catch (TransformerException e) {
    System.out.println("-- TransformerException --");
    System.out.println(e);
}

// Result
// ↓
//-- ErrorListener error --
//javax.xml.transform.TransformerException:
// The content of elements must consist of well-formed character data or markup.
//-- TransformerException --
//javax.xml.transform.TransformerException:
// org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 6;
// The content of elements must consist of well-formed character data or markup.

abstract void setOutputProperties (Properties oformat)

设置转换的输出属性。 (机器翻译)

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

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

final var transformer = TransformerFactory.newInstance().newTransformer();

{
    final var ret = transformer.getOutputProperties();
    System.out.println(ret.size()); // 0

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<?xml version="1.0" encoding="UTF-8" standalone="no"?><root><child>aaa</child></root>
    System.out.println(result.getWriter());
}

final var properties = new Properties();
properties.setProperty(OutputKeys.INDENT, "yes");
properties.setProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

transformer.setOutputProperties(properties);

{
    final var ret = transformer.getOutputProperties();
    System.out.println(ret); // {indent=yes, omit-xml-declaration=yes}

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>
    //    <child>aaa</child>
    //</root>
    System.out.println(result.getWriter());
}

abstract void setOutputProperty (String name, String value)

设置对转换有效的输出属性。 (机器翻译)

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

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

final var transformer = TransformerFactory.newInstance().newTransformer();

{
    final var ret1 = transformer.getOutputProperty(OutputKeys.INDENT);
    System.out.println(ret1); // "no"

    final var ret2 = transformer.getOutputProperty(OutputKeys.OMIT_XML_DECLARATION);
    System.out.println(ret2); // "no"

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<?xml version="1.0" encoding="UTF-8" standalone="no"?><root><child>aaa</child></root>
    System.out.println(result.getWriter());
}

transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

{
    final var ret1 = transformer.getOutputProperty(OutputKeys.INDENT);
    System.out.println(ret1); // "yes"

    final var ret2 = transformer.getOutputProperty(OutputKeys.OMIT_XML_DECLARATION);
    System.out.println(ret2); // "yes"

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>
    //    <child>aaa</child>
    //</root>
    System.out.println(result.getWriter());
}

abstract void setParameter (String name, Object value)

为转换添加一个参数。 (机器翻译)

final var xml = """
        <root/>
        """;

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

final var xsl = """
        <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
          <xsl:output omit-xml-declaration="yes" />
          <xsl:param name="param">aaaa</xsl:param>

          <xsl:template match="root">
            <xsl:copy-of select="$param" />
          </xsl:template>

        </xsl:stylesheet>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer(
        new StreamSource(new ByteArrayInputStream(xsl.getBytes())));

System.out.println(transformer.getParameter("param")); // null
transformer.setParameter("param", "bbbb");

{
    System.out.println(transformer.getParameter("param")); // bbbb

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //bbbb
    System.out.println(result.getWriter());
}

transformer.clearParameters();

{
    System.out.println(transformer.getParameter("param")); // null

    final var source = new DOMSource(document);
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //aaaa
    System.out.println(result.getWriter());
}

abstract void setURIResolver (URIResolver resolver)

设置一个用于解析 document() 中使用的 URI 的对象。 (机器翻译)

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

Files.writeString(sampleA, """
        <root>aaa</root>
        """);

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

Files.writeString(sampleB, """
        <root>bbb</root>
        """);

final var xml = """
        <root/>
        """;

final var xsl = """
        <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
          <xsl:output omit-xml-declaration="yes" />
          <xsl:variable name="doc" select="document('file:///R:/java-work/sample-a.xml')" />

          <xsl:template match="/">
            <xsl:copy-of select="$doc" />
          </xsl:template>

        </xsl:stylesheet>
        """;

final var factory = TransformerFactory.newInstance();
final var transformer = factory.newTransformer(
        new StreamSource(new ByteArrayInputStream(xsl.getBytes())));

{
    System.out.println(transformer.getURIResolver()); // null

    final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>aaa</root>
    System.out.println(result.getWriter());
}

final var urlResolver = new URIResolver() {
    @Override
    public Source resolve(String href, String base) {
        if ("file:///R:/java-work/sample-a.xml".equals(href)) {
            return new StreamSource("file:///R:/java-work/sample-b.xml");
        }

        return null;
    }
};

transformer.setURIResolver(urlResolver);

{
    System.out.println(transformer.getURIResolver() == urlResolver); // true

    final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
    final var result = new StreamResult(new StringWriter());
    transformer.transform(source, result);

    //<root>bbb</root>
    System.out.println(result.getWriter());
}

abstract void transform (Source xmlSource, Result outputTarget)

将 XML 源转换为结果。 (机器翻译)

// DOM -> XML text

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
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 transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

final var source = new DOMSource(document);
final var result = new StreamResult(new StringWriter());
transformer.transform(source, result);

//<root>abcd</root>
System.out.println(result.getWriter());

// Transforms an XML text with XSL.

final var xml = """
        <root>abcd</root>
        """;

final var xsl = """
        <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
          <xsl:output omit-xml-declaration="yes" />

          <xsl:template match="/">012<xsl:value-of select="." />XYZ</xsl:template>

        </xsl:stylesheet>
        """;

final var transformer = TransformerFactory.newInstance().newTransformer(
        new StreamSource(new ByteArrayInputStream(xsl.getBytes())));

final var source = new StreamSource(new ByteArrayInputStream(xml.getBytes()));
final var result = new StreamResult(new StringWriter());
transformer.transform(source, result);

//012abcdXYZ
System.out.println(result.getWriter());

// DOM → SAX

final var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
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 transformer = TransformerFactory.newInstance().newTransformer();

final var handler = new DefaultHandler() {

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) {
        System.out.println("startElement : " + qName);
    }

    @Override
    public void endElement(String uri, String localName, String qName) {
        System.out.println("endElement : " + qName);
    }

    @Override
    public void characters(char[] ch, int start, int length) {
        System.out.println("text : " + new String(ch, start, length));
    }
};

final var source = new DOMSource(document);
final var result = new SAXResult(handler);

//startElement : root
//text : abcd
//endElement : root
transformer.transform(source, result);

API 示例

Java : Transformer (XML) 示例

简介

Constructors

Transformer ()

Methods

abstract void clearParameters ()

abstract ErrorListener getErrorListener ()

abstract Properties getOutputProperties ()

abstract String getOutputProperty (String name)

abstract Object getParameter (String name)

abstract URIResolver getURIResolver ()

void reset ()

abstract void setErrorListener (ErrorListener listener)

abstract void setOutputProperties (Properties oformat)

abstract void setOutputProperty (String name, String value)

abstract void setParameter (String name, Object value)

abstract void setURIResolver (URIResolver resolver)

abstract void transform (Source xmlSource, Result outputTarget)

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