XML 中的双星号注释表示法

发布于 2024-12-14 20:29:34 字数 184 浏览 0 评论 0原文

在 XML 中使用双星号来指示行注释是否有效？我在分配给我解析的 XML 文件中经常看到这种情况。

例子：

</someClosingTag>
** This is my line comment in an XML file.
<someOpeningTag>

原文

Is it valid to use a double-asterisk to indicate a line-comment in XML? I see this a lot in the XML files I've been assigned to parse.

Example:

</someClosingTag>
** This is my line comment in an XML file.
<someOpeningTag>

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看透却不说透 2024-12-21 20:29:34

XML 标准中没有任何内容（ http://www.w3.org/TR/xml/ ）关于 ** 作为有效注释（正确的符号是：

<!-- My comment -->

）。

但是，我编写了一个 C#.Net 程序来使用 .Net 2.0 System.Xml.XmlReader 类来解析 XML，但它因我拥有的 ** 值而卡住了。我没有将其用作评论；这是一个合法的字符串值。经过进一步的实验，我发现它会被任何星号字符阻塞，甚至是一个星号字符，如下所示：

<?xml version="1.0" standalone="yes"?><HVACRJob Version="32">5 * 3 = 15</HVACRJob>

生成的异常是：

[XmlException: Unexpected end of file has occurred. The following elements are not closed: HVACRJob. Line 1, position 25.]
System.Xml.XmlTextReaderImpl.Throw(Exception e) +95
System.Xml.XmlTextReaderImpl.ThrowUnclosedElements() +354
System.Xml.XmlTextReaderImpl.ParseElementContent() +5088529
System.Xml.XmlReader.ReadToFollowing(String name) +92
MyApp.ParseXmlBytesIntoDictionary(Dictionary`2 Dict, Byte[] ItemAsUncompressedXmlBytes, Boolean AllowOverwrite) in c:\dev\bin\MyApp.aspx.cs:464
MyApp.CreateDictionaryFromXml(String Xml, Int32& Version) in c:\dev\bin\MyApp.aspx.cs:447
MyApp.GetEmailFromXml(String Xml) in c:\dev\bin\MyApp.aspx.cs:402
MyApp.btnSubmit_Click(Object sender, EventArgs e) in c:\dev\bin\MyApp.aspx.cs:2155
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +115
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +140
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +29
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2981

这里有两个奇怪的东西。首先，当我使用 XmlTextWriter 生成 XML 时，星号没有以任何方式分隔（但 XmlReader 无法将其读回）。其次，在谷歌搜索之后，我在网络上找不到其他人遇到这个问题。我无法想象为什么这么多年过去了，没有人会在 XML 值中使用星号，从而不报告这一点。

解决方法非常简单 - 只需将星号的任何实例替换为：

根据 XML 标准，这是合法的，并且 System.Xml.XmlReader 对此没有任何问题。如果您使用 XmlTextWriter 生成 XML，那么您必须在事后为此做一个创可贴；可能

Xml = Xml.Replace("*", "*")

没问题，因为我认为星号不会在 XML 中用于任何其他目的。

There is nothing in the XML standard ( http://www.w3.org/TR/xml/ ) about ** as a valid comment (the correct notation is:

<!-- My comment -->

However, I wrote a C#.Net program to parse XML using the .Net 2.0 System.Xml.XmlReader class, and it choked on a ** value that I had. I was not using it as a comment; it was a legitimate string value. After doing further experimentation, I found that it choked on ANY asterisk character, even a single one, like this:

<?xml version="1.0" standalone="yes"?><HVACRJob Version="32">5 * 3 = 15</HVACRJob>

The exception generated was:

[XmlException: Unexpected end of file has occurred. The following elements are not closed: HVACRJob. Line 1, position 25.]
System.Xml.XmlTextReaderImpl.Throw(Exception e) +95
System.Xml.XmlTextReaderImpl.ThrowUnclosedElements() +354
System.Xml.XmlTextReaderImpl.ParseElementContent() +5088529
System.Xml.XmlReader.ReadToFollowing(String name) +92
MyApp.ParseXmlBytesIntoDictionary(Dictionary`2 Dict, Byte[] ItemAsUncompressedXmlBytes, Boolean AllowOverwrite) in c:\dev\bin\MyApp.aspx.cs:464
MyApp.CreateDictionaryFromXml(String Xml, Int32& Version) in c:\dev\bin\MyApp.aspx.cs:447
MyApp.GetEmailFromXml(String Xml) in c:\dev\bin\MyApp.aspx.cs:402
MyApp.btnSubmit_Click(Object sender, EventArgs e) in c:\dev\bin\MyApp.aspx.cs:2155
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +115
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +140
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +29
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2981

Two weird things here. First, when I use XmlTextWriter to generate XML, the asterisk is not delimited in any way (yet XmlReader can't read it back in). Second, after Googling, I can't find anyone else on the web having this problem. I can't imagine why, after all these years, no one would ever use an asterisk in an XML value and thus not report this.

The workaround is quite simple - just replace any instance of an asterisk with:

This is legal according to the XML standard and System.Xml.XmlReader has no problems with it. If you're using XmlTextWriter to generate XML, you'll have to do a band-aid for this after the fact; probably