我们使用 Saxon 生成一些导出文件。 这些转换通常由相继应用的多个 XSLT 转换组成。 为了提高性能，我引入了使用
XMLFilters编码有效，并且性能显着提升。
但是，某些导出不是 XML，而是基于文本。 尽管在最后一个 XSLT 中设置了
omit-xml-declaration="yes"旧的实现也使用 Saxon，在没有 XML 声明的情况下产生相同的输出，尽管速度较慢。
我尽可能地减少了这两种实现并创建了一个单元测试，希望看看哪个差异会导致效果。但到目前为止还没有运气。 我错过了什么？
实际转换是在
saxonWithDestinations()saxonWithXMLFilters()import net.sf.saxon.lib.Feature;
import net.sf.saxon.s9api.Processor;
import net.sf.saxon.s9api.SaxonApiException;
import net.sf.saxon.s9api.Serializer;
import org.junit.Assert;
import org.junit.Test;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLFilter;
import org.xml.sax.XMLReader;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.Templates;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
public class SaxonXMLFilterTest {
@Test
public void compareTransformationResultsForXml() throws Exception {
compareTransformations("nop", false);
}
@Test
public void compareTransformationResultsForText() throws Exception {
compareTransformations("text", false);
}
@Test
public void compareTransformationResultsForTextWithHackEnabled() throws Exception {
compareTransformations("text", true);
}
private void compareTransformations(String styleSheetName, boolean cutOffXmlDeclaration) throws ParserConfigurationException, TransformerException, SAXException, SaxonApiException, IOException {
String resultStringWithDestination = saxonWithDestinations(getXMLData(), getStylesheetSource(styleSheetName));
String resultStringWithXMLFilters = saxonWithXMLFilters(getXMLData(), getStylesheetSource(styleSheetName));
// This hack removes the XML declaration before comparing the results
if (cutOffXmlDeclaration == true) {
resultStringWithXMLFilters = resultStringWithDestination.replace("<?xml version=\"1.0\" encoding=\"UTF-8\"?>", "");
}
Assert.assertEquals(resultStringWithDestination, resultStringWithXMLFilters);
}
public String saxonWithDestinations(InputStream dataStream, StreamSource stylesheetSource) throws SaxonApiException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
Processor processor = buildProcessor();
Serializer destination = processor.newSerializer(out);
net.sf.saxon.s9api.XsltTransformer transformer = processor.newXsltCompiler().compile(stylesheetSource).load();
transformer.setSource(new StreamSource(dataStream));
transformer.setDestination(destination);
transformer.transform();
return out.toString();
}
private String saxonWithXMLFilters(InputStream dataStream, StreamSource stylesheetSource) throws ParserConfigurationException, SAXException, TransformerException {
String implementationClassName = "net.sf.saxon.TransformerFactoryImpl"; // Force the usage of Saxon-HE
SAXTransformerFactory transformerFactory = (SAXTransformerFactory) TransformerFactory.newInstance(implementationClassName, null);
XMLReader reader = SAXParserFactory.newInstance().newSAXParser().getXMLReader();
// Build Filter and use reader as first parent
Templates template = transformerFactory.newTemplates(stylesheetSource);
XMLFilter filter = transformerFactory.newXMLFilter(template);
filter.setParent(reader);
//
// More filters to be added here
//
XMLFilter lastFilter = filter;
// Push data through filter chain into ByteArrayOutputStream
ByteArrayOutputStream out = new ByteArrayOutputStream();
transformerFactory.newTransformer().transform(new SAXSource(lastFilter, new InputSource(dataStream)), new StreamResult(out));
return out.toString();
}
public static Processor buildProcessor() {
Processor processor = new Processor(false);
processor.setConfigurationProperty(Feature.TIMING, false);
processor.setConfigurationProperty(Feature.COMPILE_WITH_TRACING, false);
return processor;
}
private static StreamSource getStylesheetSource(String styleSheetName) throws IOException {
switch (styleSheetName) {
case "nop":
return stringToStreamSource(
"""
<xsl:stylesheet version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="@*|node()">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
"""
);
case "text":
return stringToStreamSource(
"""
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output encoding="utf-8" method="text" indent="no" omit-xml-declaration="yes" xml:space="default"/>
<xsl:template match="/">
<xsl:apply-templates select="Data/Measurement" />
</xsl:template>
<xsl:template match="Data/Measurement">
<xsl:apply-templates select="x"/><xsl:text>|</xsl:text>
<xsl:apply-templates select="y"/><xsl:text>|</xsl:text>
<xsl:apply-templates select="z"/><xsl:text>
</xsl:text>
</xsl:template>
<xsl:template match="x|y|z">
<xsl:apply-templates select="*"/>
</xsl:template>
<xsl:template match="*">
<xsl:apply-templates select="text()"/>
<xsl:if test="not(position() = last())">
<xsl:text>;</xsl:text>
</xsl:if>
</xsl:template>
</xsl:stylesheet>
"""
);
default:
throw new IllegalArgumentException("Unknown stylesheet '" + styleSheetName + "'");
}
}
private InputStream getXMLData() {
return stringToInputStream(
"""
<?xml version="1.0" encoding="UTF-8"?>
<Data>
<Measurement>
<x>
<max>60.00</max>
<value>50.00</value>
<min>-40.00</min>
<unit>mm</unit>
</x>
<y>
<max>3.00</max>
<value>0.00</value>
<min>-3.00</min>
<unit>kN</unit>
</y>
<z>
<max>0.00</max>
<value>0.00</value>
<min>0.00</min>
<unit>ms</unit>
</z>
</Measurement>
<Measurement>
<x>
<max>260.00</max>
<value>250.00</value>
<min>160.00</min>
<unit>mm</unit>
</x>
<y>
<max>203.00</max>
<value>200.00</value>
<min>197.00</min>
<unit>kN</unit>
</y>
<z>
<max>600000.00</max>
<value>400000.00</value>
<min>200000.00</min>
<unit>ms</unit>
</z>
</Measurement>
</Data>
"""
);
}
private static StreamSource stringToStreamSource(String s) {
return new StreamSource(stringToInputStream(s));
}
private static InputStream stringToInputStream(String s) {
return new ByteArrayInputStream(s.getBytes(Charset.defaultCharset()));
}
}
首先观察到，omit-xml-declaration 对 method="text" 没有影响，因为文本输出方法不发出 XML 声明。
事实上，最终的序列化不是由任何 XSLT 过程完成的，而是由 JAXP 身份转换器完成的：
transformerFactory.newTransformer().transform(
new SAXSource(lastFilter, new InputSource(dataStream)),
new StreamResult(out));
根据您的类路径，可能会或可能不会使用 Saxon。您可以使用 JAXP API (
Transformer.setOutputProperty()我建议按照 Martin Honnen 的建议使用 s9api API。