Saxon 中的 BaseUri 在尝试编译 xslt 内容时导致问题

Question

这是我的代码：

static void Main(string[] args)
{
    string xml = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/data.xml");
    string xslt = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/dataXslt.xsl");
    string xmlCopy = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/data.xml");

    TransformData(xml, xmlCopy, xslt);
}

static public void TransformData(string data, string xmlCopy, string xslt)
{
    // Create a Processor instance.
    Processor processor = new Processor();

    // Create a compiled stylesheet
    processor.NewXsltCompiler().BaseUri = new Uri("C:/Users/Davíð/source/Saxon/Saxon");
    XsltExecutable templates = processor.NewXsltCompiler().Compile(new XmlTextReader(new StringReader(xslt)));

    // Note: we could actually use the same Xslt30Transformer in this case.
    // But in principle, the two transformations could be done in parallel in separate threads.

    // Do the first transformation
    Console.WriteLine("\n\n----- transform of " + data + " -----");
    Xslt30Transformer transformer1 = templates.Load30();
    XdmNode input1 = processor.NewDocumentBuilder().Build(new XmlTextReader(new StringReader(data)));
    transformer1.ApplyTemplates(input1, processor.NewSerializer(Console.Out));     // default destination is Console.Out

    // Do the second transformation
    Console.WriteLine("\n\n----- transform of " + xmlCopy + " -----");
    Xslt30Transformer transformer2 = templates.Load30();
    XdmNode input2 = processor.NewDocumentBuilder().Build(new XmlTextReader(new StringReader(xmlCopy)));
    transformer2.ApplyTemplates(input2, processor.NewSerializer(Console.Out));     // default destination is Console.Out
}

无论我是否删除 BaseUri，这都是我不断收到的错误。

未处理的异常：System.ArgumentNullException：值不能为空。 参数名称：BaseUri 在 Saxon.Api.XsltCompiler.Compile（XmlReader 阅读器） 在 C:\Users\Davíð\source\Saxon\Saxon\Program.cs:line 33 中的 Saxon.Program.TransformData(String data, String xmlCopy, String xslt) 在 C:\Users\Davíð\source\Saxon\Saxon\Program.cs:line 22 中的 Saxon.Program.Main(String[] args) 处

---

基于 cmets，固定 & 工作代码如下：

static void Main(string[] args)

{
    string xml = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/data.xml");
    string xslt = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/dataXslt.xsl");

    TransformData(xml, xml, xslt);
}

static public void TransformData(string data, string xmlCopy, string xslt)
{
    // Create a Processor instance.
    Processor processor = new Processor();

    // Create a compiled stylesheet
    var compiler = processor.NewXsltCompiler();
    compiler.BaseUri = new Uri("C:/Users/Davíð/source/Saxon/Saxon");
    XsltExecutable templates = compiler.Compile(XmlReader.Create(new StringReader(xslt)));

    // Note: we could actually use the same Xslt30Transformer in this case.
    // But in principle, the two transformations could be done in parallel in separate threads.

    // Do the first transformation
    Console.WriteLine("\n\n----- transform of " + data + " -----");
    Xslt30Transformer transformer1 = templates.Load30();
    XdmNode input1 = processor.NewDocumentBuilder().Build(XmlReader.Create(new StringReader(data)));
    transformer1.ApplyTemplates(input1, processor.NewSerializer(Console.Out));     // default destination is Console.Out

    // Do the second transformation
    Console.WriteLine("\n\n----- transform of " + xmlCopy + " -----");
    Xslt30Transformer transformer2 = templates.Load30();
    XdmNode input2 = processor.NewDocumentBuilder().Build(new XmlTextReader(new StringReader(xmlCopy)));
    transformer2.ApplyTemplates(input2, processor.NewSerializer(Console.Out));     // default destination is Console.Out
}

Answer 1

你有几个问题：

• processor.NewXsltCompiler() 每次调用都会返回一个新的XsltCompiler。你称它两次：

  processor.NewXsltCompiler().BaseUri = new Uri("C:/Users/Davíð/source/Saxon/Saxon");
  XsltExecutable templates = processor.NewXsltCompiler().Compile(new XmlTextReader(new StringReader(xslt)));
  

  代码在第一个设置BaseUri，然后创建另一个进行编译。因此，BaseUri 永远不会设置在实际用于工作的 XsltCompiler 上。

  这是异常的直接原因未处理的异常：System.ArgumentNullException：值不能为空。参数名称：BaseUri at Saxon.Api.XsltCompiler.Compile(XmlReader reader)。

  您应该只创建一个XsltCompiler。

• 您使用的是 XmlTextReader，但 XmlTextReader has been deprecated since .Net 2.0 是 10 多年前的事了。相反，请使用XmlReader.Create(TextReader)。此外，请务必在之后处理它。

• 您将文件data.xml 内容的两个副本加载到内存中，分别加载到字符串xml 和xmlCopy 中。但是 .Net 中的字符串是不可变的，所以没有必要这样做。

因此您的代码应如下所示：

public static void Main(string[] args)
{
    string xml = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/data.xml");
    string xslt = File.ReadAllText("C:/Users/Davíð/source/Saxon/Saxon/dataXslt.xsl");

    TransformData(xml, xml, xslt);
}

static public void TransformData(string xml1, string xml2, string xslt)
{
    // Create a Processor instance.
    var processor = new Processor();

    // Create a compiled stylesheet
    var compiler = processor.NewXsltCompiler();
    compiler.BaseUri = new Uri("C:/Users/Davíð/source/Saxon/Saxon");
    XsltExecutable templates;
    using (var reader = XmlReader.Create(new StringReader(xslt)))
        templates = compiler.Compile(reader);

    // Note: we could actually use the same Xslt30Transformer in this case.
    // But in principle, the two transformations could be done in parallel in separate threads.

    // Do the first transformation
    Console.WriteLine("\n\n----- transform of " + xml1 + " -----");
    TransformData(processor, templates, xml1, Console.Out);

    // Do the second transformation
    Console.WriteLine("\n\n----- transform of " + xml2 + " -----");
    TransformData(processor, templates, xml2, Console.Out);
}

private static void TransformData(Processor processor, XsltExecutable templates, string xml, TextWriter output)
{
    var transformer = templates.Load30();
    using (var reader = XmlReader.Create(new StringReader(xml)))
    {
        var input = processor.NewDocumentBuilder().Build(reader);
        transformer.ApplyTemplates(input, processor.NewSerializer(output));
    }
}