如何使用XSLT遍历字母表？

<?xml version="1.0" encoding="UTF-8"?>
<letters>
  <letter id="1">A</letter>
  <letter id="2">B</letter>
  <letter id="3">C</letter>
  <!-- 其他字母 -->
</letters>

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <xsl:apply-templates select="letters/letter"/>
  </xsl:template>
  
  <xsl:template match="letter">
    <xsl:value-of select="."/>
    <xsl:text> </xsl:text> <!-- 输出字母后添加一个空格 -->
  </xsl:template>
</xsl:stylesheet>

import javax.xml.transform.*;
import javax.xml.transform.stream.*;

public class XSLTExample {
  public static void main(String[] args) {
    try {
      TransformerFactory factory = TransformerFactory.newInstance();
      Source xslt = new StreamSource(new FileInputStream("letters.xslt"));
      Transformer transformer = factory.newTransformer(xslt);
      
      Source text = new StreamSource(new FileInputStream("letters.xml"));
      transformer.transform(text, new StreamResult(new FileOutputStream("output.txt")));
      
      System.out.println("XSLT transformation completed.");
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}