如何读写拥有命名空间xmlns 属性的Xml文件(C#实现)

我们在进行C#项目Xml读写开发时经常遇到一些读写问题，今天我要介绍的是遇到多个命名空间xmlns属性时如何读写此类文件。

　　比如下面这个Xml文件：

<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
  <root>
    <branch Name="Branch10" Value="abc">
      <leaf Name="leaf11" Value="bcd" />
      <leaf Name="leaf12" Value="cde" />
      <leaf Name="leaf13" Value="def" />
    </branch>
  </root>
</project>

　　这个文件有一个默认的命名空间：

  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

还有两个拥有前缀x和d的命名空间：

  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"   xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

  这类Xml文件的读写方法如下：

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Xml;
using System.Xml.Linq;

namespace ReadXml
{
    class Program
    {
        static void Main(string[] args)
        {
            XmlDocument xmlDoc = new XmlDocument();
            XmlReaderSettings settings = new XmlReaderSettings();
            settings.IgnoreComments = true;
            XmlReader reader = XmlReader.Create("./test.xml");

            xmlDoc.Load(reader);
            reader.Close();

            XmlNamespaceManager xmlNamespaceManager = new XmlNamespaceManager(xmlDoc.NameTable);
            xmlNamespaceManager.AddNamespace("e", "http://schemas.microsoft.com/winfx/2006/xaml/presentation");
            xmlNamespaceManager.AddNamespace("x", "http://schemas.microsoft.com/winfx/2006/xaml");
            xmlNamespaceManager.AddNamespace("d", "http://schemas.microsoft.com/expression/blend/2008");

            //读xml
            XmlNodeList nodeList = xmlDoc.SelectNodes("e:project/e:root/e:branch/e:leaf", xmlNamespaceManager);
            foreach (XmlNode item in nodeList)
            {
                Console.WriteLine(item.OuterXml);
            }

            //增加一条leaf
            XmlNode xmlNode = xmlDoc.SelectSingleNode("e:project/e:root/e:branch", xmlNamespaceManager);
            var ns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation";

            XmlElement leafElement = xmlDoc.CreateElement("leaf", ns);

            leafElement.SetAttribute("Name", "leaf14");
            leafElement.SetAttribute("value", "efg");

            xmlNode.AppendChild(leafElement);

            xmlDoc.Save("./test.xml");

            Console.WriteLine("增加一条leaf后：");

            XmlNodeList nodeListAdd = xmlDoc.SelectNodes("e:project/e:root/e:branch/e:leaf", xmlNamespaceManager);

            foreach (XmlNode item in nodeListAdd)
            {
                Console.WriteLine(item.OuterXml);
            }

            //修改一条leaf
            XmlNodeList nodeList1 = xmlDoc.SelectNodes("e:project/e:root/e:branch/e:leaf", xmlNamespaceManager);

            for (int i = (nodeList1.Count - 1); i >= 0; i--)
            {
                XmlElement xe = (XmlElement)nodeList1[i];

                if (xe.GetAttribute("Name") == "leaf11")
                {
                    xe.SetAttribute("Value", "aaa");
                }
            }

            xmlDoc.Save("./test.xml");

            Console.WriteLine("修改第一条leaf后：");
            XmlNodeList nodeListUpdate = xmlDoc.SelectNodes("e:project/e:root/e:branch/e:leaf", xmlNamespaceManager);

            foreach (XmlNode item in nodeListUpdate)
            {
                Console.WriteLine(item.OuterXml);
            }

            Console.ReadKey();
        }
    }
}

　　程序运行后控制台显示如下：

<leaf Name="leaf11" Value="bcd" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf12" Value="cde" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf13" Value="def" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
增加一条leaf后：
<leaf Name="leaf11" Value="bcd" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf12" Value="cde" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf13" Value="def" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf14" value="efg" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
修改第一条leaf后：
<leaf Name="leaf11" Value="aaa" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf12" Value="cde" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf13" Value="def" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />
<leaf Name="leaf14" value="efg" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" />

　　新的Xml显示如下：

<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
  <root>
    <branch Name="Branch10" Value="abc">
      <leaf Name="leaf11" Value="aaa" />
      <leaf Name="leaf12" Value="cde" />
      <leaf Name="leaf13" Value="def" />
      <leaf Name="leaf14" value="efg" />
    </branch>
  </root>
</project>

部分启发来自于：https://www.programering.com/a/MjMyUDNwATk.html