C#操作XML

已知有一个XML文件（bookstore.xml）如下： 
<? xml version = " 1.0 "  encoding = " gb2312 " ?>  
< bookstore >  
     < book genre = " fantasy "  ISBN = " 2-3631-4 " >  
         < title > Oberon ' s Legacy</title> 
         < author > Corets, Eva </ author >  
         < price > 5.95 </ price >  
     </ book >  
</ bookstore >  

1 、往 < bookstore > 节点中插入一个 < book > 节点： 
XmlDocument xmlDoc = new  XmlDocument(); 
xmlDoc.Load( " bookstore.xml " ); 
XmlNode root = xmlDoc.SelectSingleNode( " bookstore " ); // 查找<bookstore> 
XmlElement xe1 = xmlDoc.CreateElement( " book " ); // 创建一个<book>节点 
xe1.SetAttribute( " genre " , " 李赞红 " ); // 设置该节点genre属性 
xe1.SetAttribute( " ISBN " , " 2-3631-4 " ); // 设置该节点ISBN属性 

XmlElement xesub1 = xmlDoc.CreateElement( " title " ); 
xesub1.InnerText = " CS从入门到精通 " ; // 设置文本节点 
xe1.AppendChild(xesub1); // 添加到<book>节点中 
XmlElement xesub2 = xmlDoc.CreateElement( " author " ); 
xesub2.InnerText = " 候捷 " ; 
xe1.AppendChild(xesub2); 
XmlElement xesub3 = xmlDoc.CreateElement( " price " ); 
xesub3.InnerText = " 58.3 " ; 
xe1.AppendChild(xesub3); 

root.AppendChild(xe1); // 添加到<bookstore>节点中 
xmlDoc.Save( " bookstore.xml " ); 
// =============================================== 
结果为： 
<? xml version = " 1.0 "  encoding = " gb2312 " ?>  
< bookstore >  
     < book genre = " fantasy "  ISBN = " 2-3631-4 " >  
         < title > Oberon ' s Legacy</title> 
         < author > Corets, Eva </ author >  
         < price > 5.95 </ price >  
     </ book >  
     < book genre = " 李赞红 "  ISBN = " 2-3631-4 " >  
         < title > CS从入门到精通 </ title >  
         < author > 候捷 </ author >  
         < price > 58.3 </ price >  
     </ book >  
</ bookstore >  

2 、修改节点：将genre属性值为“李赞红“的节点的genre值改为“update李赞红”，将该节点的子节点 < author > 的文本修改为“亚胜”。 
XmlNodeList nodeList = xmlDoc.SelectSingleNode( " bookstore " ).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("genre")=="李赞红")//如果genre属性值为“李赞红” 
{ 
xe.SetAttribute("genre","update李赞红");//则修改该属性为“update李赞红” 

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=="author")//如果找到 
{ 
xe2.InnerText="亚胜";//则修改 
break;//找到退出来就可以了 
} 
} 
break; 
} 
}  

xmlDoc.Save( " bookstore.xml " ); // 保存。 
// ================================================== 
最后结果为： 
<? xml version = " 1.0 "  encoding = " gb2312 " ?>  
< bookstore >  
< book genre = " fantasy "  ISBN = " 2-3631-4 " >  
< title > Oberon ' s Legacy</title> 
< author > Corets, Eva </ author >  
< price > 5.95 </ price >  
</ book >  
< book genre = " update李赞红 "  ISBN = " 2-3631-4 " >  
< title > CS从入门到精通 </ title >  
< author > 亚胜 </ author >  
< price > 58.3 </ price >  
</ book >  
</ bookstore >  

3 、删除  < book genre = " fantasy "  ISBN = " 2-3631-4 " > 节点的genre属性，删除  < book genre = " update李赞红 "  ISBN = " 2-3631-4 " > 节点。 
XmlNodeList xnl = xmlDoc.SelectSingleNode( " bookstore " ).ChildNodes; 

foreach (XmlNode xn  in  xnl) 
{ 
XmlElement xe=(XmlElement)xn; 
if(xe.GetAttribute("genre")=="fantasy") 
{ 
xe.RemoveAttribute("genre");//删除genre属性 
} 
else if(xe.GetAttribute("genre")=="update李赞红") 
{ 
xe.RemoveAll();//删除该节点的全部内容 
} 
}  
xmlDoc.Save( " bookstore.xml " ); 
// =========================================== 
最后结果为： 
<? xml version = " 1.0 "  encoding = " gb2312 " ?>  
< bookstore >  
< book ISBN = " 2-3631-4 " >  
< title > Oberon ' s Legacy</title> 
< author > Corets, Eva </ author >  
< price > 5.95 </ price >  
</ book >  
< book >  
</ book >  
</ bookstore >  

4 、显示所有数据。 
XmlNode xn = xmlDoc.SelectSingleNode( " bookstore " ); 

XmlNodeList xnl = xn.ChildNodes; 

foreach (XmlNode xnf  in  xnl) 
{ 
XmlElement xe=(XmlElement)xnf; 
Console.WriteLine(xe.GetAttribute("genre"));//显示属性值 
Console.WriteLine(xe.GetAttribute("ISBN")); 

XmlNodeList xnf1=xe.ChildNodes; 
foreach(XmlNode xn2 in xnf1) 
{ 
Console.WriteLine(xn2.InnerText);//显示子节点点文本 
} 
}