如何在C＃中使用XmlDocument停止空的XML元素自关闭？ [英] How can I stop empty XML elements self-closing using XmlDocument in C#?
问题描述
在我被人们说XML解析器不关心元素是空还是自封闭之前，我有一个原因不允许我自封闭XML元素。原因是我实际上是在使用SGML而不是XML，并且正在使用的SGML DTD非常严格并且不允许使用。
Before I get jumped on by people saying the XML parser shouldn’t care if the elements are empty or self-closed, there is a reason why I can’t allow self-closed XML elements. The reason is that I’m actually working with SGML not XML and the SGML DTD I’m working with is very strict and doesn't allow it.
我拥有的是运行XSLT所需的数千个SGML文件。因此，为了应用XSLT，我不得不暂时将SGML转换为XML。然后，我编写了一种将它们转换回SGML的方法（基本上只是将XML声明替换为SGML声明，然后写回其他任何实体声明，例如图形实体）。
What I have is several thousand SGML files which I’ve needed to run XSLT on. I’ve therefore had to convert the SGML to XML temporarily in order to apply the XSLT. I’ve then written a method that converts them back to SGML (essentially just replacing the XML declaration with the SGML declaration and writing back any other entity declarations such as graphic entities).
我的问题是，在转换回SGML之后，当我在SGML编辑器中打开文件时，由于空元素是自关闭。
My problem is that after this conversion back to SGML, when I open the files in my SGML editor, the files don’t parse as the empty elements have been self-closed.
有人知道我在使用XmlDocument时可以如何阻止这种情况吗？
Does anybody know how I can stop this happening please when using XmlDocument?
将SGML转换为XML并再次返回的方法如下所示：
The methods that convert the SGML to XML and back again are shown below
//converts the SGML file to XML – it’s during this conversion that the
//empty elements get self-closed, i think
private XmlDocument convertToXML(TextReader reader)
{
// setup SgmlReader
Sgml.SgmlReader sgmlReader = new Sgml.SgmlReader();
//sgmlReader.DocType = "HTML";
sgmlReader.WhitespaceHandling = WhitespaceHandling.All;
sgmlReader.CaseFolding = Sgml.CaseFolding.ToLower;
sgmlReader.InputStream = reader;
// create document
XmlDocument doc = new XmlDocument();
doc.PreserveWhitespace = true;
doc.XmlResolver = null;
doc.Load(sgmlReader);
return doc;
}
// method to apply the XSLT stylesheet to the XML document
private void filterApplic(string applicFilter)
{
string stylesheet = getRequiredStylesheet(); // do this just once
if (stylesheet != "")
{
foreach (string file in FilesToConvert)
{
fileName = Path.GetFileName(file); //gets just the file name from the path
fileNameNoExt = Path.GetFileNameWithoutExtension(file);
string ext = Path.GetExtension(file);
if (ext == ".sgm")
{
try
{
publicIdentifier = getDoctype(file); // gets the sgml declaration
entitiesList = getEntitites(file); // gets the list of entities
TextReader tr = new StreamReader(file);
myDoc = convertToXML(tr);
myDoc.Save(outputFolder + "\\temp.xml");
var myXslTrans = new XslCompiledTransform();
myXslTrans.Load(stylesheet);
myXslTrans.Transform(outputFolder + "\\temp.xml", Path.Combine(outputFolder, fileNameNoExt +".xml"));
XmlDocument convertedDoc = new XmlDocument();
convertedDoc.Load(Path.Combine(outputFolder, fileNameNoExt + ".xml"));
convertToSGM(convertedDoc);
filesTransformed++;
}
catch (Exception e)
{
MessageBox.Show(e.ToString());
}
}
}
}
else
{
MessageBox.Show("The stylesheet was retured empty. Cannot perform Applicability filter.");
return;
}
MessageBox.Show("Complete! " + filesTransformed.ToString() + " files filtered for " + applicFilter);
}
//convert files back to SGML
private void convertToSGM(XmlDocument myDoc)
{
using (var stringWriter = new StringWriter())
using (var xmlTextWriter = XmlWriter.Create(stringWriter, settings))
{
myDoc.WriteTo(xmlTextWriter);
xmlTextWriter.Flush();
string xmltext = stringWriter.GetStringBuilder().ToString();
xmltext = xmltext.Replace("<?xml version=\"1.0\" encoding=\"utf-16\"?>", "<!DOCTYPE DMODULE " + publicIdentifier + ">");
xmltext = xmltext.Replace("<?xml version=\"1.0\" encoding=\"utf-8\"?>", "<!DOCTYPE DMODULE " + publicIdentifier + ">");
if (entitiesList.Count != 0)
{
string entityListAsOne = "";
foreach (string entity in entitiesList)
{
entityListAsOne = entityListAsOne + "\r\n" + entity;
}
xmltext = xmltext.Replace("//EN\">", "//EN\" [" + entityListAsOne + "]>");
}
File.WriteAllText(Path.Combine(outputFolder, fileNameNoExt + ".sgm"), xmltext);
}
}
推荐答案
一种方法是将适当的 XmlWriter 并覆盖 WriteEndElement（） 来调用 WriteFullEndElement（） 。
One way to do it would be to subclass an appropriate XmlWriter and override WriteEndElement() to call WriteFullEndElement().
例如，这是 XmlTextWriter 完成任务：
For instance, here's a subclassed version of XmlTextWriter that does the job:
public class FullElementXmlTextWriter : XmlTextWriter
{
public FullElementXmlTextWriter(TextWriter w) : base(w) { }
public FullElementXmlTextWriter(Stream w, Encoding encoding) : base(w, encoding) { }
public FullElementXmlTextWriter(string filename, Encoding encoding) : base(filename, encoding) { }
public override void WriteEndElement()
{
base.WriteFullEndElement();
}
}
然后使用它：
string xmltext;
using (var stringWriter = new StringWriter())
{
using (var xmlTextWriter = new FullElementXmlTextWriter(stringWriter))
{
myDoc.WriteTo(xmlTextWriter);
}
xmltext = stringWriter.ToString();
}
或者，如果您需要 XmlWriterSettings提供的控件，您可以使用装饰器模式将任何 XmlWriter 封装在装饰器中，该装饰器会自动重新映射来自 WriteEndElement（）的调用到 WriteFullEndElement（）：
Or, if you need the control afforded by XmlWriterSettings, you can use the decorator pattern to encapsulate any XmlWriter in a decorator that automatically remaps calls from WriteEndElement() to WriteFullEndElement():
public class FullElementXmlWriterDecorator : XmlWriterDecorator
{
public FullElementXmlWriterDecorator(XmlWriter baseWriter) : base(baseWriter) { }
public override void WriteEndElement()
{
base.WriteFullEndElement();
}
}
public class XmlWriterDecorator : XmlWriter
{
readonly XmlWriter baseWriter;
public XmlWriterDecorator(XmlWriter baseWriter)
{
if (baseWriter == null)
throw new ArgumentNullException();
this.baseWriter = baseWriter;
}
protected virtual bool IsSuspended { get { return false; } }
public override void Close()
{
baseWriter.Close();
}
public override void Flush()
{
baseWriter.Flush();
}
public override string LookupPrefix(string ns)
{
return baseWriter.LookupPrefix(ns);
}
public override void WriteBase64(byte[] buffer, int index, int count)
{
if (IsSuspended)
return;
baseWriter.WriteBase64(buffer, index, count);
}
public override void WriteCData(string text)
{
if (IsSuspended)
return;
baseWriter.WriteCData(text);
}
public override void WriteCharEntity(char ch)
{
if (IsSuspended)
return;
baseWriter.WriteCharEntity(ch);
}
public override void WriteChars(char[] buffer, int index, int count)
{
if (IsSuspended)
return;
baseWriter.WriteChars(buffer, index, count);
}
public override void WriteComment(string text)
{
if (IsSuspended)
return;
baseWriter.WriteComment(text);
}
public override void WriteDocType(string name, string pubid, string sysid, string subset)
{
if (IsSuspended)
return;
baseWriter.WriteDocType(name, pubid, sysid, subset);
}
public override void WriteEndAttribute()
{
if (IsSuspended)
return;
baseWriter.WriteEndAttribute();
}
public override void WriteEndDocument()
{
if (IsSuspended)
return;
baseWriter.WriteEndDocument();
}
public override void WriteEndElement()
{
if (IsSuspended)
return;
baseWriter.WriteEndElement();
}
public override void WriteEntityRef(string name)
{
if (IsSuspended)
return;
baseWriter.WriteEntityRef(name);
}
public override void WriteFullEndElement()
{
if (IsSuspended)
return;
baseWriter.WriteFullEndElement();
}
public override void WriteProcessingInstruction(string name, string text)
{
if (IsSuspended)
return;
baseWriter.WriteProcessingInstruction(name, text);
}
public override void WriteRaw(string data)
{
if (IsSuspended)
return;
baseWriter.WriteRaw(data);
}
public override void WriteRaw(char[] buffer, int index, int count)
{
if (IsSuspended)
return;
baseWriter.WriteRaw(buffer, index, count);
}
public override void WriteStartAttribute(string prefix, string localName, string ns)
{
if (IsSuspended)
return;
baseWriter.WriteStartAttribute(prefix, localName, ns);
}
public override void WriteStartDocument(bool standalone)
{
baseWriter.WriteStartDocument(standalone);
}
public override void WriteStartDocument()
{
baseWriter.WriteStartDocument();
}
public override void WriteStartElement(string prefix, string localName, string ns)
{
if (IsSuspended)
return;
baseWriter.WriteStartElement(prefix, localName, ns);
}
public override WriteState WriteState
{
get { return baseWriter.WriteState; }
}
public override void WriteString(string text)
{
if (IsSuspended)
return;
baseWriter.WriteString(text);
}
public override void WriteSurrogateCharEntity(char lowChar, char highChar)
{
if (IsSuspended)
return;
baseWriter.WriteSurrogateCharEntity(lowChar, highChar);
}
public override void WriteWhitespace(string ws)
{
if (IsSuspended)
return;
baseWriter.WriteWhitespace(ws);
}
}
如果您正在进行异步写入，我相信（但是
If you were doing async writing, I believe (but have not tested) that you'd want to decorate the async methods as well.
然后像这样使用它：
string xmltext;
using (var stringWriter = new StringWriter())
{
using (var innerXmlWriter = XmlWriter.Create(stringWriter, settings))
using (var xmlTextWriter = new FullElementXmlWriterDecorator(innerXmlWriter))
{
myDoc.WriteTo(xmlTextWriter);
}
xmltext = stringWriter.ToString();
}
小提琴。
这篇关于如何在C＃中使用XmlDocument停止空的XML元素自关闭？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
