基于C#中XmlWriter写入Xml的深入分析

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假定创建了XmlWriter的实例变量xmlWriter，下文中将使用此实例变量写Xml
1.如何使用XmlWriter写Xml文档声明

// WriteStartDocument方法可以接受一个bool参数（表示standalone，是否为独立文档）或者不指定参数standalone保持默认值 
xmlWriter.WriteStartDocument(false|true); 

注意在使用WriteStartDocument方法后最好调用xmlWrite.WriteEndDocument()方法来关闭所有可能未关闭标签
2.如何使用XmlWriter写xml节点以及属性

复制代码代码如下:

//写节点 
xmlWriter.WriteStartElement("cat"); 
//给节点添加属性 
xmlWriter.WriteAttributeString("color", "white"); 
//给节点内部添加文本 
xmlWriter.WriteString("I'm a cat"); 
xmlWriter.WriteEndElement(); 

或者通过WriteElementString(string,string)方法写xml节点同时写下节点值，如下

复制代码代码如下:

//通过WriteElementString可以添加一个节点同时添加节点内容 
xmlWriter.WriteElementString("pig", "pig is great"); 

3.如何写CData

复制代码代码如下:

xmlWriter.WriteStartElement("dog"); 
//写CData 
xmlWriter.WriteCData("<strong>dog is dog</strong>"); 
xmlWriter.WriteEndElement(); 

4.如何使用XmlWriter添加注释

复制代码代码如下:

xmlWriter.WriteComment("this is an example writed by https://www.jb51.net ");

5.如何设置XmlWriter的输出格式，解决输出UTF-16问题
设置xml输出格式，需要通过XmlWriterSettings类，如下代码

复制代码代码如下:

XmlWriterSettings settings = new XmlWriterSettings(); 
//要求缩进 
settings.Indent = true; 
//注意如果不设置encoding默认将输出utf-16 
//注意这儿不能直接用Encoding.UTF8如果用Encoding.UTF8将在输出文本的最前面添加4个字节的非xml内容 
settings.Encoding = new UTF8Encoding(false); 

//设置换行符 
settings.NewLineChars = Environment.NewLine;

完整的代码示例如下：

复制代码代码如下:

using System; 
using System.Collections.Generic; 
using System.Text; 
using System.IO; 
using System.Xml; 

namespace UseXmlWriter 
{ 
    class Program 
    { 
        static void Main(string[] args) 
        { 
            using (MemoryStream ms = new MemoryStream()) 
            { 
                XmlWriterSettings settings = new XmlWriterSettings(); 
                //要求缩进 
                settings.Indent = true; 
                //注意如果不设置encoding默认将输出utf-16 
                //注意这儿不能直接用Encoding.UTF8如果用Encoding.UTF8将在输出文本的最前面添加4个字节的非xml内容 
                settings.Encoding = new UTF8Encoding(false); 

                //设置换行符 
                settings.NewLineChars = Environment.NewLine; 

                using (XmlWriter xmlWriter = XmlWriter.Create(ms, settings)) 
                { 

                    //写xml文件开始<?xml version="1.0" encoding="utf-8" ?> 
                    xmlWriter.WriteStartDocument(false); 
                    //写根节点 
                    xmlWriter.WriteStartElement("root"); 
                    //写字节点 
                    xmlWriter.WriteStartElement("cat"); 
                    //给节点添加属性 
                    xmlWriter.WriteAttributeString("color", "white"); 
                    //给节点内部添加文本 
                    xmlWriter.WriteString("I'm a cat"); 
                    xmlWriter.WriteEndElement(); 

  
                    //通过WriteElementString可以添加一个节点同时添加节点内容 
                    xmlWriter.WriteElementString("pig", "pig is great"); 

  
                    xmlWriter.WriteStartElement("dog"); 
                    //写CData 
                    xmlWriter.WriteCData("<strong>dog is dog</strong>"); 
                    xmlWriter.WriteEndElement(); 

                    xmlWriter.WriteComment("this is an example writed by  https://www.jb51.net "); 

                    xmlWriter.WriteEndElement(); 
                    xmlWriter.WriteEndDocument(); 

                } 

                //将xml内容输出到控制台中 
                string xml = Encoding.UTF8.GetString(ms.ToArray()); 
                Console.WriteLine(xml); 
            } 
            Console.Read(); 

        } 
    } 
}