XmlReader和MemoryStream，返回的xml缺少标签

Question

有人可以向我解释这种行为吗？

如果您使用第一个字符串执行帖子底部的代码片段，它将返回与用于输入的字符串完全相同的字符串；这就是我所期望的。

输入 1：

<?xml version='1.0' encoding='UTF-8'?>
<Company>
  <Creator>Me</Creator>
  <CreationDateTime>2010-01-25T21:58:32.493</CreationDateTime>
  <Contacts>
    <Contact>
      <ContactID>365</ContactID>
    </Contact>
  </Contacts>
</Company>

输出 1：

<?xml version='1.0' encoding='UTF-8'?>
<Company>
  <Creator>Me</Creator>
  <CreationDateTime>2010-01-25T21:58:32.493</CreationDateTime>
  <Contacts>
    <Contact>
      <ContactID>365</ContactID>
    </Contact>
  </Contacts>
</Company>

现在，如果您使用第二行 (const string xml)，这与字符串完全相同，但在一行而不是两行上，则返回以下

输入 2

<?xml version='1.0' encoding='UTF-8'?>
<Company>
  <Creator>Me</Creator>
  <CreationDateTime>2010-01-25T21:58:32.493</CreationDateTime>
  <Contacts>
    <Contact>
      <ContactID>365</ContactID>
    </Contact>
  </Contacts>
</Company>

输出 2

<?xml version='1.0' encoding='UTF-8'?>
<Creator>Me</Creator>2010-01-25T21:58:32.493 
<Contacts>
  <Contact>
    <ContactID>365</ContactID>
  </Contact>
</Contacts>

唯一的区别两者之间的区别是，第一个输出在 xml 声明之后有一个换行符，但正如您所看到的，第二个输出缺少父标记和第三个标记。有什么想法吗？

这是我使用的代码：

public void XmlReader_Eats_Tags_IsTrue()
    {
        //this first xml declaration is on two lines - line break is right after the xml declaration (I am not sure how to add the line break using the markdown, so if you execute the code on your machine, please add it)
        const string xml = @"<?xml version='1.0' encoding='UTF-8'?><Company><Creator>Me</Creator><CreationDateTime>2010-01-25T21:58:32.493</CreationDateTime><Contacts><Contact><ContactID>365</ContactID></Contact></Contacts></Company>";

        //The seconde xml declaration is on one line
        //const string xml = @"<?xml version='1.0' encoding='UTF-8'?><Company><Creator>Me</Creator><CreationDateTime>2010-01-25T21:58:32.493</CreationDateTime><Contacts><Contact><ContactID>365</ContactID></Contact></Contacts></Company>";

        BufferedStream stream = new BufferedStream(new MemoryStream());
        stream.Write(Encoding.ASCII.GetBytes(xml), 0, xml.Length);
        stream.Seek(0, SeekOrigin.Begin);
        StreamReader streamReaderXml = new StreamReader(stream);

        XmlReader xmlR = XmlReader.Create(streamReaderXml);

        XmlReaderSettings xmlReaderset = 
                         new XmlReaderSettings{ValidationType = ValidationType.Schema};
        xmlReaderset.Schemas.ValidationEventHandler += ValidationCallBack;

        MemoryStream ms = new MemoryStream();
        XmlWriterSettings xmlWriterSettings = 
                          new XmlWriterSettings{
                                  Encoding = new UTF8Encoding(false),
                                  ConformanceLevel = ConformanceLevel.Fragment
                          };

        using (XmlWriter xmlTw = XmlWriter.Create(ms, xmlWriterSettings))
        {
            using (XmlReader xmlRead = XmlReader.Create(xmlR, xmlReaderset))
            {
                int i = 0;
                while (xmlRead.Read())
                {
                    Console.WriteLine("{0}:{1}; node type: {2}", i, xmlRead.Name, xmlRead.NodeType);
                    // Reads the whole file and will call the validation handler subroutine if an error is detected.
                    xmlTw.WriteNode(xmlRead, true);
                    i++;
                }

                xmlTw.Flush();
                xmlRead.Close();
            }
            string xmlString = Encoding.UTF8.GetString(ms.ToArray());
            Console.WriteLine(xmlString);
        }
    }

Answer 1

问题是您正在使用 XmlWriter.WriteNode(reader, true) 并调用 XmlReader.Read()。 WriteNode 已经将读取器移动到同级元素上，因此当您再次调用 Read 时，您实际上会跳过数据。

我怀疑它碰巧在第一个版本中工作，因为您在第二次调用Read时跳过了空格，然后在第二个版本中读取文档的其余部分调用WriteNode。