asp.net操作xml（增删查改）

asp.net操作xml

1.xml文档Products.xml

 <?xml version="1.0" encoding="utf-8"?>
 <products xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.pro.org/2001/products" xsi:schemaLocation="http://www.pro.org/2001/products products.xsd">
   <item belong="数码">
     <id>1</id>
     <name>手机</name>
     <price>1000</price>
   </item>
   <item belong="服装">
     <id>2</id>
     <name>男装</name>
     <price>200</price>
   </item>
   <item belong="食品">
     <id>3</id>
     <name>黄瓜</name>
     <price>4</price>
   </item>
 </products>

 2.schema约束文档 products.xml

 <?xml version="1.0" encoding="utf-8"?>
 <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.pro.org/2001/products" xmlns:pro="http://www.pro.org/2001/products" elementFormDefault="qualified">
   <element name="products" type="pro:pro"></element>
   <complexType name="pro">
     <sequence>
       <element name="item" maxOccurs="unbounded">
         <complexType>
           <sequence>
             <element name="id" type="string"></element>
             <element name="name" type="string"></element>
             <element name="price">
               <simpleType>
                 <restriction base="float">
                   <maxExclusive value="10000"></maxExclusive>
                   <minInclusive value="0"></minInclusive>
                 </restriction>
               </simpleType>
             </element>
           </sequence>
           <attribute name="belong" type="string"></attribute>
         </complexType>
       </element>
     </sequence>
   </complexType>
 </schema>

3.定义实体类 DBPro.cs

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;

 /// <summary>
 ///DBPro 的摘要说明
 /// </summary>
 public class DBPro
 {
     string belong;
     string id;
     string name;
     string price;
     public DBPro(string belong,string id,string name,string price)
     {
         this.belong = belong;
         this.id = id;
         this.name = name;
         this.price = price;
     }
     public string Belong
     {
         get { return belong; }
         set { belong = value; }
     }
     public string ID
     {
         get { return id; }
         set { id = value; }
     }
     public string Name
     {
         get { return name; }
         set{name=value;}
     }
     public string Price
     {
         get { return price; }
         set { price = value; }
     }
 }

4.新建一个web窗体Defaut.aspx，在Default.aspx.cs中编写核心代码

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Web.UI;
 using System.Web.UI.WebControls;
 using System.Xml;

 public partial class _Default : System.Web.UI.Page
 {
     protected void Page_Load(object sender, EventArgs e)
     {   //选择方法进行测试
         //SearchXml();
         DBPro pro = new DBPro("家电","10", "电视", "3999");
         AddToXml(pro);
         //UpdateOneXml(pro);
         //DeleteXml("10");
     }
     /// <summary>
     /// 遍历xml文档
     /// </summary>
     /// <param name="pro"></param>
     private void SearchXml()
     {
         //提取xml文档
         XmlDocument xd = new XmlDocument();
         xd.Load(System.Web.HttpContext.Current.Server.MapPath("Products.xml"));
         //获取根节点
         XmlNode root = xd.DocumentElement;
         //获取节点列表
         XmlNodeList items = root.ChildNodes;
         //遍历item项
         Response.Write("<pre>");
         foreach (XmlNode item in items)
         {
          //输出属性
             Response.Write(item.Attributes["belong"].Name + "=" + item.Attributes["belong"].InnerText);
             //遍历输出子节点
             foreach (XmlNode p in item)
             {
                 Response.Write(p.Name + "=" + p.InnerText);
             }
         }
         Response.Write("</pre>");
     }
     /// <summary>
     /// xml添加
     /// </summary>
     /// <param name="pro"></param>
     private void AddToXml(DBPro pro)
     {
         //提取xml文档
         XmlDocument xd = new XmlDocument();
         xd.Load(System.Web.HttpContext.Current.Server.MapPath("Products.xml"));
         //获取根节点
         XmlNode root = xd.DocumentElement;
         //创建元素
         XmlElement newItem = xd.CreateElement("item");
         XmlElement newID = xd.CreateElement("id");
         XmlElement newName = xd.CreateElement("name");
         XmlElement newPrice = xd.CreateElement("price");
         //配置参数
         newItem.SetAttribute("belong", pro.Belong);
         newID.InnerText = pro.ID;
         newName.InnerText = pro.Name;
         newPrice.InnerText = pro.Price;
         //装配
         root.AppendChild(newItem);
         newItem.AppendChild(newID);
         newItem.AppendChild(newName);
         newItem.AppendChild(newPrice);
         xd.Save(System.Web.HttpContext.Current.Server.MapPath("Products.xml"));
     }
     /// <summary>
     /// 修改xml一项
     /// </summary>
     /// <param name="pro"></param>
     private void UpdateOneXml(DBPro pro)
     {
         //提取xml文档
         XmlDocument xd = new XmlDocument();
         xd.Load(System.Web.HttpContext.Current.Server.MapPath("Products.xml"));
         //获取根节点
         XmlNode root = xd.DocumentElement;
         //获取节点列表
         XmlNodeList items = root.ChildNodes;
         //遍历节点列表
         foreach (XmlNode item in items)
         {
             //遍历item
             foreach (XmlNode p in item)
             {
                 if (p.Name == "id" && p.InnerText == pro.ID)
                 {
                     item.Attributes["belong"].InnerText = pro.Belong;
                     p.NextSibling.InnerText = pro.Name;
                     p.NextSibling.NextSibling.InnerText = pro.Price;
                 }
             }
         }
     }
     /// <summary>
     /// 删除xml一项
     /// </summary>
     /// <param name="pro"></param>
     private void DeleteXml(string id)
     {
          //提取xml文档
         XmlDocument xd = new XmlDocument();
         xd.Load(System.Web.HttpContext.Current.Server.MapPath("Products.xml"));
         //获取根节点
         XmlNode root = xd.DocumentElement;
         //获取节点列表
         XmlNodeList items = root.ChildNodes;
         //遍历节点列表
         foreach (XmlNode item in items)
         {
             //遍历item
             foreach (XmlNode p in item)
             {
                 if (p.Name == "id" && p.InnerText == id)
                 {
                     root.RemoveChild(item);
                 }
             }
         }
     }
 }

此处应注意：用XMLDocument添加元素，遇到了这样一个问题：
当根节点具有 xmlns 属性时，用 XMLDocument 创建子元素时如果不指定 xmlns 或指定 xmlns 为 null 时，子元素将自动具有 xmlns="" 属性

<item belong="家电" xmlns="">
    <id>10</id>
    <name>电视</name>
    <price>3999</price>
  </item>
问题原因：

当父节点具有 xmlns 属性时，子节点必须指定 xmlns 属性，仅当子节点的 xmnls 属性与父节点相同时，子节点才不显示 xmlns 属性，最终就不会在 .xml 文件中显示出来

解决办法:

XmlElement newItem = xd.CreateElement("item",xd.DocumentElement.NamespaceURI);
        XmlElement newID = xd.CreateElement("id",xd.DocumentElement.NamespaceURI);
        XmlElement newName = xd.CreateElement("name",xd.DocumentElement.NamespaceURI);
        XmlElement newNumber = xd.CreateElement("number",xd.DocumentElement.NamespaceURI);

在每一个下级节点，都要继续指定命名空间，否则仍会出现 xmlns="" 属性。

///新手上道，若有不足或错误之处，敬请各位大神批评指正！