C# 创建XML文档

有些时候我们需要生成一个xml文档作为数据交换的容器。当然我们用拼接字符串的方法来进行构建xml，但是这种方法虽然简单有效，但是如果xml文档结构过于复杂，拼接字符串会让人眼花缭乱。这时候就需要C#给我们提供现成的类库，以供我们自由的创建xml文档。

比如我们要创建如下的xml文档

<?xml version="1.0" encoding="UTF-8"?>
<ns0:Z_AVS_UPLOAD_WEIGHT_Request xmlns:ns0="http://schemas.microsoft.com/BizTalk/2003">   
    <ZWERKS>ZFM1</ZWERKS>
    <TAB1>
        <ZNO>13022101</ZNO>
        <ZORDER>2013238955</ZORDER>
        <ZWEIGHT>4140</ZWEIGHT>
    </TAB1>
    <TAB1>
        <ZNO>13022101</ZNO>
        <ZORDER>2013239627</ZORDER>
        <ZWEIGHT>4140</ZWEIGHT>
    </TAB1>
</ns0:Z_AVS_UPLOAD_WEIGHT_Request>

选取这样的结构，一方面是因为它来自于论坛某位坛友实际的需求，另一方面它足够简单却有代表性。

下面我将以这个例子用两种方法（XmlDocument和Linq to XML）进行讲解。

1、XmlDocument

            XmlDocument document = new XmlDocument();

            XmlDeclaration declaration = document.CreateXmlDeclaration("1.0", "UTF-8", "");//xml文档的声明部分
            document.AppendChild(declaration);

            XmlElement root = document.CreateElement("ns0", "Z_AVS_UPLOAD_WEIGHT_Request", "http://schemas.microsoft.com/BizTalk/2003");
            document.AppendChild(root);

            XmlElement zwerks = document.CreateElement("ZWERKS");
            zwerks.InnerText = "ZFM1";
            root.AppendChild(zwerks);

            XmlElement tab1 = document.CreateElement("TAB1");
            root.AppendChild(tab1);

            XmlElement zno = document.CreateElement("ZNO");
            zno.InnerText = "13022101";
            tab1.AppendChild(zno);

            XmlElement zorder = document.CreateElement("ZORDER");
            zorder.InnerText = "2013238955";
            tab1.AppendChild(zorder);

            XmlElement zweight = document.CreateElement("ZWEIGHT");
            zweight.InnerText = "4140";
            tab1.AppendChild(zweight);

            XmlElement tab2 = document.CreateElement("TAB1");
            root.AppendChild(tab2);

            XmlElement zno2 = document.CreateElement("ZNO");
            zno2.InnerText = "13022101";
            tab2.AppendChild(zno2);

            XmlElement zorder2 = document.CreateElement("ZORDER");
            zorder2.InnerText = "2013238955";
            tab2.AppendChild(zorder2);

            XmlElement zweight2 = document.CreateElement("ZWEIGHT");
            zweight2.InnerText = "4140";
            tab2.AppendChild(zweight2);

            document.Save("test.xml");//将生成好的xml保存到test.xml文件中

2、Linq to XML

            XDocument document = new XDocument();
            document.Declaration = new XDeclaration("1.0", "UTF-8", "");

            XNamespace ns = "http://schemas.microsoft.com/BizTalk/2003";

            XElement root = new XElement(ns + "Z_AVS_UPLOAD_WEIGHT_Request",
                new XAttribute(XNamespace.Xmlns + "ns0", "http://schemas.microsoft.com/BizTalk/2003"));

            root.Add(new XElement("ZWERKS", "ZFM1"),
                new XElement("TAB1",
                    new XElement("ZNO", 13022101),
                    new XElement("ZORDER", 2013238955),
                    new XElement("ZWEIGHT", 4140)),
                new XElement("TAB1",
                    new XElement("ZNO", 13022101),
                    new XElement("ZORDER", 2013238955),
                    new XElement("ZWEIGHT", 4140))
                    );

            document.Add(root);
            document.Save("test.xml");//保存xml到文件

可以发现Linq to XML的方法比较简洁，代码量也足够小。当然了XmlDocument的方法可以进一步的简化，这里重点展示一下Linq to XML的魅力。如上只当给需要的朋友提供一下思路和解决方案。关于Linq to xml的更多信息可以参考：XNamespace。

再提供一个例子：

有a.xml：

<a>
    <xingming>
        <item>
            <name>张三</name>
            <code>1</code>
        </item>
        <item>
            <name>李四</name>
            <code>2</code>
        </item>
        <item>
            <name>王五</name>
            <code>3</code>
        </item>
        <item>
            <name>赵四</name>
            <code>4</code>
        </item>
        <item>
            <name>王二麻子</name>
            <code>5</code>
        </item>
    </xingming>
    <nianji>
        <item>
            <name>一年级</name>
            <banji>一班</banji>
        </item>
    </nianji>
</a>

想转换成b.xml：

<b>
  <xingming>
    <items>
      <item>
        <Xingname1>张三</Xingname1>
        <Xingcode1>1</Xingcode1>
        <Xingname2>李四</Xingname2>
        <Xingcode2>2</Xingcode2>
      </item>
      <item>
        <Xingname1>王五</Xingname1>
        <Xingcode1>3</Xingcode1>
        <Xingname2>赵四</Xingname2>
        <Xingcode2>4</Xingcode2>
      </item>
      <item>
        <Xingname1>王二麻子</Xingname1>
        <Xingcode1>5</Xingcode1>
      </item>
    </items>
  </xingming>
  <nianji>
    <item>
      <name>一年级</name>
      <name>一班</name>
    </item>
  </nianji>
</b>

代码如下：

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string xml = @"<a>
    <xingming>
        <item>
            <name>张三</name>
            <code>1</code>
        </item>
        <item>
            <name>李四</name>
            <code>2</code>
        </item>
        <item>
            <name>王五</name>
            <code>3</code>
        </item>
        <item>
            <name>赵四</name>
            <code>4</code>
        </item>
        <item>
            <name>王二麻子</name>
            <code>5</code>
        </item>
    </xingming>
    <nianji>
        <item>
            <name>一年级</name>
            <banji>一班</banji>
        </item>
    </nianji>
</a>";

            XmlDocument newXmlDoc = new XmlDocument();
            XmlElement b = newXmlDoc.CreateElement("b");
            newXmlDoc.AppendChild(b);

            XmlElement xingming = newXmlDoc.CreateElement("xingming");
            b.AppendChild(xingming);

            XmlElement items = newXmlDoc.CreateElement("items");
            xingming.AppendChild(items);

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.LoadXml(xml);

            XmlElement item = null;

            //直接定位到/a/xingming节点下的子节点
            var nodes = xmlDoc.SelectSingleNode("/a/xingming").ChildNodes;

            for (int i = 0; i < nodes.Count; i++)
            {
                XmlNode node = nodes.Item(i);

                //节点项为偶数时，创建item节点
                if (i % 2 == 0)
                {
                    item = newXmlDoc.CreateElement("item");
                    items.AppendChild(item);
                }

                //item节点追加Xingname节点
                XmlElement Xingname = newXmlDoc.CreateElement("Xingname" + (i % 2 + 1));
                Xingname.InnerText = node.SelectSingleNode("name").InnerText;
                item.AppendChild(Xingname);

                //item节点追加Xingcode节点
                XmlElement Xingcode = newXmlDoc.CreateElement("Xingcode" + (i % 2 + 1));
                Xingcode.InnerText = node.SelectSingleNode("code").InnerText;
                item.AppendChild(Xingcode);

            }

            XmlElement nianji = newXmlDoc.CreateElement("nianji");
            b.AppendChild(nianji);

            XmlElement item1 = newXmlDoc.CreateElement("item");
            nianji.AppendChild(item1);

            XmlElement name = newXmlDoc.CreateElement("name");
            name.InnerText = xmlDoc.SelectSingleNode("/a/nianji/item/name").InnerText;
            item1.AppendChild(name);

            XmlElement banji = newXmlDoc.CreateElement("name");
            banji.InnerText = xmlDoc.SelectSingleNode("/a/nianji/item/banji").InnerText;
            item1.AppendChild(banji);

            newXmlDoc.Save("b.xml");
        }
    }
}

再附一个例子，生成指定格式的xml文档：

<?xml version="1.0" encoding="utf-8"?>
<response>
  <code>0</code>
  <date_list>
    <godate>2017-08-09</godate>
    <godate>2017-08-19</godate>
  </date_list>
</response>

代码如下：

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            response r = new response()
            {
                code = 0,
                date_list = new date_list()
                {
                    godate = new string[]
                    {
                        "2017-08-09",
                        "2017-08-19"
                    }
                }
            };
            XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
            ns.Add("", "");

            XmlWriterSettings settings = new XmlWriterSettings();
            settings.Encoding = Encoding.UTF8;
            settings.Indent = true;

            XmlWriter writer = XmlWriter.Create("test.xml", settings);
            XmlSerializer s = new XmlSerializer(typeof(response));
            s.Serialize(writer, r, ns);
            writer.Close();
        }
    }

    [Serializable]
    public class response
    {
        public int code { get; set; }
        public date_list date_list { get; set; }
    }

    [Serializable]
    public class date_list
    {
        [XmlElement("godate")]
        public string[] godate { get; set; }
    }
}