Xml Tips

Xml Tips



1. xml 中的注释

<!-- 这是注释 -->

并非用于 XML 分析器的内容（例如与文档结构或编辑有关的说明）可以包含在注释中。注释以 <!-- 开头，以 --> 结尾，例如<!--catalog last updated 2000-11-01-->。

注释可以出现在文档序言中，包括文档类型定义 (DTD)；文档之后；或文本内容中。注释不能出现在属性值中。不能出现在标记中。

分析器在遇到 > 时，就认为注释已结束；然后继续将文档作为正常的 XML 处理。因此，字符串 >

以下注释可以用于暂时除去标记。

<!--- <test pattern="SECAM" /><test pattern="NTSC" /> -->

2. 验证 xml 的合法性

??感觉不合适

public class MyXmlDocument: XmlDocument
{
  bool TryParseXml(string xml){
    try{
      ParseXml(xml);
      return true;
    }catch(XmlException e){
      return false;
    }
 }

Using a XmlValidatingReader will prevent the exceptions, if you provide your own ValidationEventHandler.

using System;
using System.Xml;
using System.Xml.Schema;
using System.Xml.XPath;

class XPathValidation
 {
     static void Main()
     {
         try
         {
             XmlReaderSettings settings = new XmlReaderSettings();
             settings.Schemas.Add("http://www.contoso.com/books", "contosoBooks.xsd");
             settings.ValidationType = ValidationType.Schema;

             XmlReader reader = XmlReader.Create("contosoBooks.xml", settings);
             XmlDocument document = new XmlDocument();
             document.Load(reader);

             ValidationEventHandler eventHandler = new ValidationEventHandler(ValidationEventHandler);

             // the following call to Validate succeeds.
             document.Validate(eventHandler);

             // add a node so that the document is no longer valid
             XPathNavigator navigator = document.CreateNavigator();
             navigator.MoveToFollowing("price", "http://www.contoso.com/books");
             XmlWriter writer = navigator.InsertAfter();
             writer.WriteStartElement("anotherNode", "http://www.contoso.com/books");
             writer.WriteEndElement();
             writer.Close();

             // the document will now fail to successfully validate
             document.Validate(eventHandler);
         }
         catch (Exception ex)
         {
             Console.WriteLine(ex.Message);
         }
     }

     static void ValidationEventHandler(object sender, ValidationEventArgs e)
     {
         switch (e.Severity)
         {
             case XmlSeverityType.Error:
                 Console.WriteLine("Error: {0}", e.Message);
                 break;
             case XmlSeverityType.Warning:
                 Console.WriteLine("Warning {0}", e.Message);
                 break;
         }

     }
 }