使用 c# 从 Xml 片段制定格式良好的 xml

Question

我正在从一个循环中制定 xmlnodes。所以它的作用是

   var settings = new XmlWriterSettings();
   settings.OmitXmlDeclaration = true;
   settings.Indent = true;
   var ns = new XmlSerializerNamespaces();
   ns.Add("", "");
   foreach (Person human in bar)
    {
        var serializer = new XmlSerializer(typeof(Person));
        using (var stream = new FileStream(filepath, FileMode.Append))
        using (var writer = XmlWriter.Create(stream, settings))
        {
            serializer.Serialize(writer, human, ns);
        }
    }

当循环完成时，它会制定 xml 片段，输出 XML 是这样的

    <Person>
  <Name>mar8a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar1a</Name>
  <Age>1</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar2a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar3a</Name>
  <Age>1</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person><Person>
  <Name>mar4a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar5a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar6a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar7a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>
<Person>
  <Name>mar8a</Name>
  <Age>11</Age>
  <Sex>MALE</Sex>
  <Address>TOP 92 BOTTOM</Address>
  <SingleYn>false</SingleYn>
</Person>

我正在运行的问题是如何修改它并使其成为具有根节点并在循环结束时声明的格式良好的 xml。

我尝试了以下概念，但没有运气，因为它限制了我在 writer 上不写任何根元素。

        StringBuilder output = new StringBuilder();
        XmlReaderSettings ws = new XmlReaderSettings();
        ws.ConformanceLevel = ConformanceLevel.Fragment;
        String xmlString =
                @"<Item>test with a child element stuff</Item>
                <Item>test with a child element stuff</Item>";
        // Create an XmlReader
        using (XmlReader reader = XmlReader.Create(new StringReader(xmlString), ws))
        {
            XmlWriterSettings ws2 = new XmlWriterSettings();
            ws2.Indent = true;
            using (XmlWriter writer = XmlWriter.Create(output, ws2))
            {
                writer.WriteStartDocument();
                // Parse the file and display each of the nodes.
                while (reader.Read())
                {
                    switch (reader.NodeType)
                    {
                        case XmlNodeType.Element:
                            writer.WriteStartElement(reader.Name);
                            break;
                        case XmlNodeType.Text:
                            writer.WriteString(reader.Value);
                            break;
                        case XmlNodeType.XmlDeclaration:
                        case XmlNodeType.ProcessingInstruction:
                            writer.WriteProcessingInstruction(reader.Name, reader.Value);
                            break;
                        case XmlNodeType.Comment:
                            writer.WriteComment(reader.Value);
                            break;
                        case XmlNodeType.EndElement:
                            writer.WriteFullEndElement();
                            break;
                    }
                }
                writer.WriteEndDocument();

            }
        }

更新！！

这是序列化我的序列化器实现的列表的代码

        public static async Task WriteXMLAsync<T>(this List<T> listRows, T entity, VMEXPORT[] arrVmExport, string filePath)
        where T : class
    {
        XmlWriterSettings Xmlsettings = new XmlWriterSettings();
        Xmlsettings.Indent = true;
        Xmlsettings.OmitXmlDeclaration = false;
        Xmlsettings.NewLineOnAttributes = true;
        Xmlsettings.Async = true;
        Xmlsettings.Encoding = Encoding.UTF8;
        Xmlsettings.CheckCharacters = false;

        XmlAttributeOverrides Xmloverrides = new XmlAttributeOverrides();
        XmlAttributes Xmlattribs = new XmlAttributes();
        Xmlattribs.XmlIgnore = true;
        Xmlattribs.XmlElements.Add(new XmlElementAttribute("SfiObjectState"));
        Xmloverrides.Add(typeof(T), "SfiObjectState", Xmlattribs);


        if (!File.Exists(filePath))
        {
            using (var fileStream = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None, 4096, true))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(List<T>), Xmloverrides);
                using (XmlWriter xmlWriter = XmlWriter.Create(fileStream, Xmlsettings))
                {
                    serializer.Serialize(xmlWriter, listRows);
                    await xmlWriter.FlushAsync();
                }
            }
        }
        else
        {

            using (var fileStream = new FileStream(filePath, FileMode.Append, FileAccess.Write, FileShare.None, 4096, true))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(List<T>), Xmloverrides);
                using (XmlWriter xmlWriter = XmlWriter.Create(fileStream, Xmlsettings))
                {
                    serializer.Serialize(xmlWriter, listRows);
                    await xmlWriter.FlushAsync();
                }
            }


        }

    }

下面是上面实现 take 和 skip 方法的迭代

 public async Task WriteXmlDataAsync<TEntity>(IQueryable<TEntity> listToWrite, [DataSourceRequest]DataSourceRequest dataRequest,
                                          int countno, VMEXPORT[] vmExportarr, CancellationToken token,
                                          TEntity entity, string csvFileNametx, string XmlFilePathtx)
      where TEntity : class
    {
        dataRequest.GroupingToSorting();
        int datapageno = (countno / GeneralConst.L_MAX_EXPORT_REC) + 1;
        for (int ctrno = 1; ctrno <= datapageno; )
        {
            if (token.IsCancellationRequested)
            {
                RemoveTask(csvFileNametx);
                token.ThrowIfCancellationRequested();
            }
            dataRequest.Page = ctrno;
            dataRequest.PageSize = GeneralConst.L_MAX_EXPORT_REC;
            var dataSourceResult = listToWrite.ToDataSourceResult(dataRequest);
            await dataSourceResult.Data.Cast<TEntity>().ToList().WriteXMLAsync(entity, vmExportarr, XmlFilePathtx);
            ctrno = ctrno + 1;
            int percentageno = (ctrno * 100) / datapageno;
            if (percentageno > 100) percentageno = 100;
            UpdateTask(csvFileNametx, percentageno);
        }

    }

Answer 1

选项 1

在编写 XML 文件后，您可以像这样快速而肮脏地做一些事情：

    public static void AddOuterElement(string fileName, string elementName)
    {
        var startElement = string.Format(@"<{0}>", elementName);
        var endElement = string.Format(@"</{0}>", elementName);

        var tmpName = Path.GetTempFileName();
        try
        {
            using (var writer = new StreamWriter(tmpName, false, Encoding.UTF8))
            {
                writer.WriteLine(startElement);
                foreach (var line in File.ReadLines(fileName))  // Reads lines incrementally rather than all at once.
                    writer.WriteLine(line);
                writer.WriteLine(endElement);
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex);
            try
            {
                System.IO.File.Delete(tmpName);
            }
            catch (Exception)
            {
            }
            throw;
        }
        System.IO.File.Delete(fileName);
        System.IO.File.Move(tmpName, fileName);
    }

这需要两次写入 XML 文件。

选项 2

假设您有一些方法可以分块返回 Person 类的列表，例如使用以下签名：

    IEnumerable<IEnumerable<Person>> GetPeopleInChunks()
    {
        // Query the database in chunks of 200 and yield return each list.
    }

然后您可以使用以下改编自this answer 的类来顺序序列化数据库中的所有人员，而无需一次将它们全部加载到内存中：

// Proxy class for any enumerable with the requisite `Add` methods.
public class EnumerableProxy<T> : IEnumerable<T>
{
    [XmlIgnore]
    public IEnumerable<T> BaseEnumerable { get; set; }

    public void Add(T obj)
    {
        throw new NotImplementedException();
    }

    #region IEnumerable<T> Members

    public IEnumerator<T> GetEnumerator()
    {
        if (BaseEnumerable == null)
            return Enumerable.Empty<T>().GetEnumerator();
        return BaseEnumerable.GetEnumerator();
    }

    #endregion

    #region IEnumerable Members

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
        return GetEnumerator();
    }

    #endregion
}

[XmlRoot("People")]
public class People
{
    [XmlIgnore]
    public IEnumerable<Person> Results { get; set; }

    [XmlElement("Person")]
    public EnumerableProxy<Person> ResultsProxy
    {
        get
        {
            return new EnumerableProxy<Person> { BaseEnumerable = Results };
        }
        set
        {
            throw new NotImplementedException();
        }
    }
}

然后：

    public void WriteXml(string fileName)
    {
        var people = new People { Results = GetPeopleInChunks().SelectMany(chunk => chunk) };
        using (var writer = XmlWriter.Create(fileName))
        {
            new XmlSerializer(typeof(People)).Serialize(writer, people);
        }
    }

Answer 2

试试下面的方法。您还需要在根级别只有一级标签。

            XmlDocument doc = new XmlDocument();
            doc.LoadXml(xmlStr);


            XmlDeclaration xDeclare = doc.CreateXmlDeclaration("1.0", "UTF-8", null);
            XmlNode docNode = doc.CreateXmlDeclaration("1.0", "UTF-8", null);

            doc.InsertBefore(xDeclare, doc.FirstChild);

            //or
            string xml1 ="<Root>" + "Your XML" + "</Root>";

            //or
            string xml2 = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><Root>" + "Your XML" + "</Root>"; 
​

Answer 3

假设您的所有 Person 节点都在某个描述的字符串中，将其转换为文档的简单方法如下：

    XmlDocument oXmlDocument = new XmlDocument();
    oXmlDocument.AppendChild(oXmlDocument.CreateXmlDeclaration("1.0", "UTF-8", ""));

    string sFileContents = "XML Fragments In Here";

    XmlNode oRootXmlNode = oXmlDocument.CreateElement("Root");
    oRootXmlNode.InnerXml = sFileContents;

    oXmlDocument.AppendChild(oRootXmlNode);
    oXmlDocument.Save("XMLFileName.xml");

如果碎片最终变得巨大，这可能不是一个好主意。