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如何解析从字符串加载xsl的转换中包含的xsl?

xslcompiledtransform include .net-2.0 xslt c#

Cerebrus · 技术社区 · 15 年前

.NET 2.0/VS2005版

我想用 XslCompiledTransform 类来执行xsl转换。我有两个xsl文件,第一个文件包含对另一个文件的引用,其格式为 <xsl:include> 声明:

Main.xsl:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:include href="Included.xsl" />
  ...
  ...
</xsl:stylesheet>

现在,如果我可以将“main.xsl”文件本身加载为一个uri,那么我的转换代码将简单到:

// This is a function that works. For demo only.
private string Transform(string xslFileURI)
{
  XslCompiledTransform xslt = new XslCompiledTransform();

  // This load works just fine, if I provide the path to "Main.xsl".
  // The xsl:include is automatically resolved.
  xslTransform.Load(xslFileURI);

  StringWriter sw = new StringWriter();
  xslt.Transform(Server.MapPath("~/XML/input.xml"), null, sw);
  return sw.ToString();
}

问题是,我将main.xsl文件的内容作为字符串接收,并需要将该字符串作为 XmlReader/IXpathNavigable . 这是目前必要的限制。 当我试图使用 XmlReader/XpathDocument ,它失败,因为代码在 C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\ 文件夹!很明显, XmlResolver 无法解析相对url,因为它只接收字符串作为输入xsl。

我在这方面的努力看起来像:

// This doesn't work! Halp!
private string Transform(string xslContents)
{
  XslCompiledTransform xslt = new XslCompiledTransform();
  XmlUrlResolver resolver = new XmlUrlResolver();
  resolver.Credentials = CredentialCache.DefaultCredentials;

  //METHOD 1: This method does not work.
  XmlReaderSettings settings = new XmlReaderSettings();
  settings.XmlResolver = resolver;
  XmlReader xR = XmlReader.Create(new StringReader(xslContents), settings);
  xslt.Load(xR);    // fails

  // METHOD 2: Does not work either.
  XPathDocument xpDoc = new XPathDocument(new StringReader(xslContents));
  xslt.Load(xpDoc, new XsltSettings(true, true), resolver);  //fails.

  StringWriter sw = new StringWriter();
  xslt.Transform(Server.MapPath("~/XML/input.xml"), null, sw);
  return sw.ToString();
}

我试过用 ResolveUri XmlUrlResolver的方法来获取 Stream 引用要包含的xsl文件,但对如何使用此流感到困惑。听着,我该怎么告诉 XslCompiledTransform 对象以在main.xsl xmlreader之外使用此流:

Uri mainURI = new Uri(Request.PhysicalApplicationPath + "Main.xsl");
Uri uri = resolver.ResolveUri(mainURI, "Included.xsl");

// I can verify that the Included.xsl file loads in the Stream below.
Stream s = resolver.GetEntity(uri, null, typeof(Stream)) as Stream;

// How do I use this Stream in the function above??

任何帮助都非常感谢。对不起,我发了那么长的信!

为了供您参考,异常堆栈跟踪如下所示:

[FileNotFoundException: Could not find file 'C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\Included.xsl'.]
   System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) +328
   System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy) +1038
   System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize) +113
   System.Xml.XmlDownloadManager.GetStream(Uri uri, ICredentials credentials) +78
   System.Xml.XmlUrlResolver.GetEntity(Uri absoluteUri, String role, Type ofObjectToReturn) +51
   System.Xml.Xsl.Xslt.XsltLoader.CreateReader(Uri uri, XmlResolver xmlResolver) +22
   System.Xml.Xsl.Xslt.XsltLoader.LoadStylesheet(Uri uri, Boolean include) +33
   System.Xml.Xsl.Xslt.XsltLoader.LoadInclude() +349
   System.Xml.Xsl.Xslt.XsltLoader.LoadRealStylesheet() +704
   System.Xml.Xsl.Xslt.XsltLoader.LoadDocument() +293
   System.Xml.Xsl.Xslt.XsltLoader.LoadStylesheet(XmlReader reader, Boolean include) +173

4 回复 | 直到 9 年前

Gee 15 年前

使用自定义XmlUrlResolver

class MyXmlUrlResolver : XmlUrlResolver
    {
        public override Uri ResolveUri(Uri baseUri, string relativeUri)
        {
            if (baseUri != null)
                return base.ResolveUri(baseUri, relativeUri);
            else
                return base.ResolveUri(new Uri("http://mypath/"), relativeUri);
        }
    }

并将其用于xslcompiredtransform的加载函数中,

resolver=new MyXmlUrlResolver();
xslt.Load(xR,null,resolver);

David E 15 年前

我可能忽略了这一点,但是有没有理由不将included.xsl的uri更改为真正的url?这可以在xsl文档中完成,如果您有访问权限,或者使用字符串操作?

Kenny Evitt 12 年前

正如gee的回答所提到的,您需要使用 XmlResolver (其中 XmlUrlResolver 已派生),但如果还重写该方法 GetEntity 您可以以有趣和有趣的方式解析主XSLT文档中的引用。一个故意简单的例子,说明如何解析对 包含XSL :

public class CustomXmlResolver : XmlResolver
{
    public CustomXmlResolver() { }

    public override ICredentials Credentials
    {
        set { }
    }

    public override object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn)
    {
        MemoryStream entityStream = null;

        switch (absoluteUri.Scheme)
        {
            case "custom-scheme":

                string absoluteUriOriginalString = absoluteUri.OriginalString;
                string ctgXsltEntityName = absoluteUriOriginalString.Substring(absoluteUriOriginalString.IndexOf(":") + 1);
                string entityXslt = "";

                // TODO: Replace the following with your own code to load data for referenced entities.
                switch (ctgXsltEntityName)
                {
                    case "Included.xsl":
                        entityXslt = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<xsl:stylesheet version=\"1.0\" xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\">\n  <xsl:template name=\"Included\">\n\n  </xsl:template>\n</xsl:stylesheet>";
                        break;
                }

                UTF8Encoding utf8Encoding = new UTF8Encoding();
                byte[] entityBytes = utf8Encoding.GetBytes(entityXslt);
                entityStream = new MemoryStream(entityBytes);

                break;
        }

        return entityStream;
    }

    public override Uri ResolveUri(Uri baseUri, string relativeUri)
    {
        // You might want to resolve all reference URIs using a custom scheme.
        if (baseUri != null)
            return base.ResolveUri(baseUri, relativeUri);
        else
            return new Uri("custom-scheme:" + relativeUri);
    }
}

当你装载 MX.XSL 将相关代码更改为以下内容:

xslt.Load(xpDoc, new XsltSettings(true, true), new CustomXmlResolver());

上面的例子是基于MSDN文章中的信息 Resolving the Unknown: Building Custom XmlResolvers in the .NET Framework .

user3175146 9 年前

我已经成功地使用所有内存进行了转换:

包含以下内容的xslt包括:

导入ref=“common.xslt”和导入ref=“xhtml.xslt”

    private string Transform(string styleSheet, string xmlToParse)
            {
                XslCompiledTransform xslt = new XslCompiledTransform();

                MemoryResourceResolver resolver = new MemoryResourceResolver();            


                XmlTextReader xR = new XmlTextReader(new StringReader(styleSheet));           

                xslt.Load(xR, null, resolver);

                StringWriter sw = new StringWriter();                


                using (var inputReader = new StringReader(xmlToParse))
                {
                    var input = new XmlTextReader(inputReader);
                    xslt.Transform(input,
                                        null,
                                        sw);
                }

                return sw.ToString();

            }     

    public class MemoryResourceResolver : XmlResolver
        {

            public override object GetEntity(Uri absoluteUri,
              string role, Type ofObjectToReturn)
            {
                if (absoluteUri.ToString().Contains("Common"))
                {
                    return new MemoryStream(Encoding.UTF8.GetBytes("Xml with with common data"));
                }

                if (absoluteUri.ToString().Contains("Xhtml"))
                {
                    return new MemoryStream(Encoding.UTF8.GetBytes("Xml with with xhtml data"));
                }         

                return "";
            }
        }

注意,所有内容都是字符串:样式表、xmltparse和“common”和“xhtml”导入的内容