如何只创建一次根标签

本文关键字：一次 标签 创建 | 更新日期: 2023-09-27 17:53:09

尝试从FileStreame Writer类的XML文件创建XML文件，但它给了我一个错误文件Unexpected XML declaration. The XML declaration must be the first node in the document, and no white space characters are allowed to appear before it.

它创建了<?xml version='1.0' encoding='utf-8' standalone='yes'?>和根元素标签两次我的代码

using (FileStream fileStream = new FileStream(_logFilePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
                {
                    XmlDocument xmlDoc = new XmlDocument();
                    string currentDateTime = DateTime.Now.ToString("yyyyMMddHHmmss");
                    xmlDoc.Load(fileStream);
                    XmlElement newelement = xmlDoc.CreateElement("LogData");
                    XmlElement xmlLogID = xmlDoc.CreateElement("LogID");
                    XmlElement xmlLogDateTime = xmlDoc.CreateElement("LogDateTime");
                    XmlElement xmlLogType = xmlDoc.CreateElement("LogType");
                    XmlElement xmlLogFlag = xmlDoc.CreateElement("LogFlag");
                    XmlElement xmlLogApplication = xmlDoc.CreateElement("LogApplication");
                    XmlElement xmlLogModule = xmlDoc.CreateElement("LogModule");
                    XmlElement xmlLogLocation = xmlDoc.CreateElement("LogLocation");
                    XmlElement xmlLogText = xmlDoc.CreateElement("LogText");
                    XmlElement xmlLogStackTrace = xmlDoc.CreateElement("LogStackTrace");
                    xmlLogID.InnerText = _logIDPrefix + currentDateTime + randomNumber;
                    xmlLogDateTime.InnerText = currentDateTime;
                    xmlLogType.InnerText = ((LogTypes)Convert.ToInt32(logType)).ToString();
                    xmlLogFlag.InnerText = logFlag;
                    xmlLogApplication.InnerText = _logApplication;
                    xmlLogModule.InnerText = logModule;
                    xmlLogLocation.InnerText = logLocation;
                    xmlLogText.InnerText = logText;
                    xmlLogStackTrace.InnerText = logStackTrace;
                    newelement.AppendChild(xmlLogID);
                    newelement.AppendChild(xmlLogDateTime);
                    newelement.AppendChild(xmlLogType);
                    newelement.AppendChild(xmlLogFlag);
                    newelement.AppendChild(xmlLogApplication);
                    newelement.AppendChild(xmlLogModule);
                    newelement.AppendChild(xmlLogLocation);
                    newelement.AppendChild(xmlLogText);
                    xmlDoc.DocumentElement.AppendChild(newelement);
                    xmlDoc.Save(fileStream);

这些代码执行了不止一次，但我只是想防止创建<?xml version='1.0' encoding='utf-8' standalone='yes'?>和根元素wise

如何只创建一次根标签

调用Load(它将在现有文件的结束处离开流)，然后调用Save。不要在同一条流上这样做。您可以只是重新定位它，但如果新文档更短，那么您最终会遇到问题。(现在不会，将来可能会。)

我强烈建议你把它分成三个部分:

  • 创建只读取和加载现有文档的流
  • 修改内存中的文档
  • 创建一个只写(截断现有文件)的流，并保存文档
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