XSLT - 调用 Java 方法 - 给出：非静态 Java 函数“doubleIntEcho”的第一个参数不是有效的对象引用

Question

我想从 XSLT 样式表调用 Java（扩展）方法。

错误信息是：

非静态 Java 函数“doubleIntEcho”的第一个参数不是有效的对象引用。

我的简化 POC 由 4 个部分组成：

1. XML：文件

 <?xml version="1.0"?> <value> <amount>1</amount> <amount>2</amount> <amount>3</amount> </value>

2. XSLT 样式表：

 <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:jcall="java:xyzXsltCallingJavaEchoTwice"> <xsl:output method="xml"/> <xsl:template match="/value"> <value> <xsl:apply-templates select="amount"/> </value> </xsl:template> <xsl:template match="amount"> <xsl:copy> <value> <xsl:value-of select="text()"/> </value> <value-int> <xsl:value-of select="jcall:doubleIntEcho(number(.))"/> </value-int> <value-string> <xsl:value-of select="jcall:doubleStringEcho(text())"/> </value-string> </xsl:copy> </xsl:template> </xsl:stylesheet>

3.Java类带扩展名：

package x.y.z;

public class XsltCallingJavaEchoTwice {
    public static String doubleStringEcho( String input) {
        return "Source=" + input + ", echo=" + input + ", echo2=" + input;
    }
    public static int doubleIntEcho( int input) {
        return input + input;
    }
}

4. Java 环境启动 XSLT 转换过程：

public class XsltFilterParentWithAllChildren {

  private static final String XML_FILENAME = "files/xslt-call-java-amounts.xml";
  private static final String XSLT_FILENAME = "files/xslt-call-java-xsl.xsl";
  private static final String XML_OUTPUT_FILENAME = "files/output.xml";

  public static void main(String[] args) {
    deleteFile( XML_OUTPUT_FILENAME);
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try (InputStream is = new FileInputStream(XML_FILENAME)) {
      DocumentBuilder db = dbf.newDocumentBuilder();
      Document doc = db.parse(is);
      try (FileOutputStream output = new FileOutputStream(XML_OUTPUT_FILENAME)) {
        transform(doc, output);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }   
  private static void transform(Document doc, OutputStream output) throws TransformerException {
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    Transformer transformer = transformerFactory.newTransformer(
            new StreamSource(new File(XSLT_FILENAME)));
    transformer.transform(new DOMSource(doc), new StreamResult(output));
  }   
  private static void deleteFile( String pathname) {
    new File( pathname).delete();
  }
}

Answer 1

看着https://xalan.apache.org/xalan-j/extensions.html#ext-func-calls我宁愿期待例如xmlns:java="http://xml.apache.org/xalan/java"和然后例如<xsl:value-of select="java:xyzXsltCallingJavaEchoTwice.doubleIntEcho(number(.))"/> 。