如何取得XML节点的值

Question

我得到了如下的字符串，它是以XML形式表现的。如何取得 retweeted_status 下的 text 的值呢？
-------------
  <?xml version="1.0" encoding="UTF-8" ?> 
- <statuses>
- <status>
  <created_at>Fri Mar 25 16:46:11 +0800 2011</created_at> 
  <id>3444</id> 
  <text>文字文字......</text> 
- <source>
  <a href="http://1">uiououou</a> 
  </source>
  <favorited>false</favorited> 
  <truncated>false</truncated> 
  <geo /> 
  <in_reply_to_status_id /> 
  <in_reply_to_user_id /> 
  <in_reply_to_screen_name /> 
  <mid>898989889</mid> 
- <user>
  <id>7777755</id> 
  <screen_name>yuiuiu</screen_name> 
  <name>无脚鸟v</name> 
  <province>44</province> 
  <city>3</city> 
  <location>iuouo</location> 
  <description>fhgfhhgfhgfh．．．．．</description> 
  <url>http://1</url> 
  <profile_image_url>http://1</profile_image_url> 
  <domain /> 
  <gender>m</gender> 
  <followers_count>132</followers_count> 
  <friends_count>683</friends_count> 
  <statuses_count>388</statuses_count> 
  <favourites_count>0</favourites_count> 
  <created_at>Sat Oct 16 00:00:00 +0800 2010</created_at> 
  <following>false</following> 
  <verified>false</verified> 
  <allow_all_act_msg>false</allow_all_act_msg> 
  <geo_enabled>true</geo_enabled> 
  </user>
- <retweeted_status>
  <created_at>Fri Mar 25 16:25:40 +0800 2011</created_at> 
  <id>8040898773</id> 
  <text>uuuuuuuuuuukljlklkj</text> 
- <source>
  <a href="http://1">sdgfdsfsdfd</a> 
  </source>
  <favorited>false</favorited> 
  <truncated>false</truncated> 
  <geo /> 
  <in_reply_to_status_id /> 
  <in_reply_to_user_id /> 
  <in_reply_to_screen_name /> 
  <mid>6666666767</mid> 
- <user>
  <id>1645979402</id> 
  <screen_name>yutu</screen_name> 
  <name>tyuytu</name> 
  <province>31</province> 
  <city>15</city> 
  <location>上海 浦东新区</location> 
  <description>gfhfhgfhfh</description> 
  <url>http://2</url> 
  <profile_image_url>http://1</profile_image_url> 
  <domain>ghfghgfh</domain> 
  <gender>m</gender> 
  <followers_count>15339</followers_count> 
  <friends_count>349</friends_count> 
  <statuses_count>4195</statuses_count> 
  <favourites_count>0</favourites_count> 
  <created_at>Fri Mar 26 00:00:00 +0800 2010</created_at> 
  <following>false</following> 
  <verified>true</verified> 
  <allow_all_act_msg>true</allow_all_act_msg> 
  <geo_enabled>true</geo_enabled> 
  </user>
- <annotations>
- <annotation class="object">
  <cartoon type="boolean">false</cartoon> 
  </annotation>
  </annotations>
  </retweeted_status>
  <annotations /> 
  </status>
  </statuses>

Answer 1

XML操作类
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;namespace PuTianCheng
{
    /// <summary>
    /// XmlHelper 的摘要说明
    /// </summary>
    public class XmlHelper
    {
        public XmlHelper()
        {
        }        /// <summary>
        /// 读取数据
        /// </summary>
        /// <param name="path">路径</param>
        /// <param name="node">节点</param>
        /// <param name="attribute">属性名，非空时返回该属性值，否则返回串联值</param>
        /// <returns>string</returns>
        /**************************************************
         * 使用示列:
         * XmlHelper.Read(path, "/Node", "")
         * XmlHelper.Read(path, "/Node/Element[@Attribute='Name']", "Attribute")
         ************************************************/
        public static string Read(string path, string node, string attribute)
        {
            string value = "";
            try
            {
                XmlDocument doc = new XmlDocument();
                doc.Load(path);
                XmlNode xn = doc.SelectSingleNode(node);
                value = (attribute.Equals("") ? xn.InnerText : xn.Attributes[attribute].Value);
            }
            catch { }
            return value;
        }        /// <summary>
        /// 插入数据
        /// </summary>
        /// <param name="path">路径</param>
        /// <param name="node">节点</param>
        /// <param name="element">元素名，非空时插入新元素，否则在该元素中插入属性</param>
        /// <param name="attribute">属性名，非空时插入该元素属性值，否则插入元素值</param>
        /// <param name="value">值</param>
        /// <returns></returns>
        /**************************************************
         * 使用示列:
         * XmlHelper.Insert(path, "/Node", "Element", "", "Value")
         * XmlHelper.Insert(path, "/Node", "Element", "Attribute", "Value")
         * XmlHelper.Insert(path, "/Node", "", "Attribute", "Value")
         ************************************************/
        public static void Insert(string path, string node, string element, string attribute, string value)
        {
            try
            {
                XmlDocument doc = new XmlDocument();
                doc.Load(path);
                XmlNode xn = doc.SelectSingleNode(node);
                if (element.Equals(""))
                {
                    if (!attribute.Equals(""))
                    {
                        XmlElement xe = (XmlElement)xn;
                        xe.SetAttribute(attribute, value);
                    }
                }
                else
                {
                    XmlElement xe = doc.CreateElement(element);
                    if (attribute.Equals(""))
                        xe.InnerText = value;
                    else
                        xe.SetAttribute(attribute, value);
                    xn.AppendChild(xe);
                }
                doc.Save(path);
            }
            catch { }
        }        /// <summary>
        /// 修改数据
        /// </summary>
        /// <param name="path">路径</param>
        /// <param name="node">节点</param>
        /// <param name="attribute">属性名，非空时修改该节点属性值，否则修改节点值</param>
        /// <param name="value">值</param>
        /// <returns></returns>
        /**************************************************
         * 使用示列:
         * XmlHelper.Insert(path, "/Node", "", "Value")
         * XmlHelper.Insert(path, "/Node", "Attribute", "Value")
         ************************************************/
        public static void Update(string path, string node, string attribute, string value)
        {
            try
            {
                XmlDocument doc = new XmlDocument();
                doc.Load(path);
                XmlNode xn = doc.SelectSingleNode(node);
                XmlElement xe = (XmlElement)xn;
                if (attribute.Equals(""))
                    xe.InnerText = value;
                else
                    xe.SetAttribute(attribute, value);
                doc.Save(path);
            }
            catch { }
        }        /// <summary>
        /// 删除数据
        /// </summary>
        /// <param name="path">路径</param>
        /// <param name="node">节点</param>
        /// <param name="attribute">属性名，非空时删除该节点属性值，否则删除节点值</param>
        /// <param name="value">值</param>
        /// <returns></returns>
        /**************************************************
         * 使用示列:
         * XmlHelper.Delete(path, "/Node", "")
         * XmlHelper.Delete(path, "/Node", "Attribute")
         ************************************************/
        public static void Delete(string path, string node, string attribute)
        {
            try
            {
                XmlDocument doc = new XmlDocument();
                doc.Load(path);
                XmlNode xn = doc.SelectSingleNode(node);
                XmlElement xe = (XmlElement)xn;
                if (attribute.Equals(""))
                    xn.ParentNode.RemoveChild(xn);
                else
                    xe.RemoveAttribute(attribute);
                doc.Save(path);
            }
            catch { }
        }
    }
}

Answer 2

试过了，提示“System.NullReferenceException: 未将对象引用设置到对象的实例。”
那个node参数是什么？如果按我给出那些字符串？

Answer 3

那个node参数是什么？
是节点

Answer 4

"retweeted_status/text" 格式这样？

Answer 5

        XmlDocument xml = new XmlDocument();
        xml.Load(Server.MapPath("XMLFile.xml"));
        XmlNodeList node = xml.SelectNodes("//*/retweeted_status/text");
        foreach (XmlNode n in node)
        {
            Response.Write(n.InnerText);
        }
/*
uuuuuuuuuuukljlklkj 
*/

Answer 6

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Xml;
private XmlDocument xmlDoc;        //load xml file
        private void LoadXml()
        {
            xmlDoc=new XmlDocument();
            xmlDoc.Load(Server.MapPath("User.xml"));
        }
        //添加节点
        private void AddElement()
        {
            
            LoadXml();            XmlNode xmldocSelect=xmlDoc.SelectSingleNode("user");
            
            XmlElement el=xmlDoc.CreateElement("person"); //添加person节点
            el.SetAttribute("name","风云"); //添加person节点的属性"name"
            el.SetAttribute("sex","女");   //添加person节点的属性 "sex"
            el.SetAttribute("age","25");   //添加person节点的属性 "age"
            
             XmlElement xesub1=xmlDoc.CreateElement("pass"); //添加person节点的里的节点
             xesub1.InnerText="123";//设置文本节点
             el.AppendChild(xesub1);
             XmlElement xesub2=xmlDoc.CreateElement("Address");
             xesub2.InnerText="昆明";//设置文本节点
             el.AppendChild(xesub2);            xmldocSelect.AppendChild(el);
            xmlDoc.Save(Server.MapPath("user.xml"));
        }
                //修改节点
        private void UpdateElement()
        {
            LoadXml();
            XmlNodeList nodeList=xmlDoc.SelectSingleNode("user").ChildNodes;//获取bookstore节点的所有子节点
            foreach(XmlNode xn in nodeList)//遍历所有子节点
            {
                XmlElement xe=(XmlElement)xn;//将子节点类型转换为XmlElement类型
                if(xe.GetAttribute("name")=="风云")//如果name属性值为“风云”
                {
                    xe.SetAttribute("name","发明");                    
                    //如果下面有子节点在下走
                     XmlNodeList nls=xe.ChildNodes;//继续获取xe子节点的所有子节点
                    foreach(XmlNode xn1 in nls)//遍历
                    {
                       XmlElement xe2=(XmlElement)xn1;//转换类型
                        if(xe2.Name=="pass")//如果找到
                        {
                            xe2.InnerText="66666";//则修改
                            break;                        }
                    }                    break;
                }
            }
           xmlDoc.Save(Server.MapPath("user.xml"));//保存
        }
        //删出节点
        private void deleteNode()
        {
            
            LoadXml();
            XmlNodeList xnl=xmlDoc.SelectSingleNode("user").ChildNodes;
 
            foreach(XmlNode xn in xnl)
            {
                XmlElement xe=(XmlElement)xn;
                
                if(xe.GetAttribute("name")=="发明")
                {
                    //xe.RemoveAttribute("name");//删除name属性
                   // xe.RemoveAll();//删除该节点的全部内容
                    xe.ParentNode.RemoveChild(xe);
                    
                    break;
                }
                
            }
            xmlDoc.Save(Server.MapPath("user.xml"));//保存
        }        private void showIt()
        {
            LoadXml();
            XmlNode xn=xmlDoc.SelectSingleNode("user");
 
            XmlNodeList xnl=xn.ChildNodes;
   
            foreach(XmlNode xnf in xnl)
            {
                XmlElement xe=(XmlElement)xnf;
//                Console.WriteLine(xe.GetAttribute("name"));//显示属性值
//                Console.WriteLine(xe.GetAttribute("sex"));
// 
//                XmlNodeList xnf1=xe.ChildNodes;
//                foreach(XmlNode xn2 in xnf1)
//                {
//                    Console.WriteLine(xn2.InnerText);//显示子节点点文本
//                }            }        }
<?xml version="1.0" encoding="gb2312"?>
<user>
  <person>
  </person>
  <person name="ss" sex="男" age="25">
    <pass>123</pass>
    <Address>a</Address>
  </person>
  <person name="ff" sex="女" age="25">
    <pass>123</pass>
    <Address>g</Address>
  </person>
</user>

Answer 7

你看看机器人给你给你回复。
LINQ2XML