C# 创建，读取，写入XML文件

<?xml version="1.0" encoding="utf-8"?> 
<advertisements> 
 <ad> 
 <imageurl>001.jpg</imageurl> 
 <navigateurl>001.aspx</navigateurl> 
 <impressions>10</impressions> 
 <keyword>gucas01</keyword> 
 </ad> 
 <ad> 
 <imageurl>002.jpg</imageurl> 
 <navigateurl>002.aspx</navigateurl> 
 <impressions>20</impressions> 
 <keyword>gucas02</keyword> 
 </ad> 
 <ad> 
 <imageurl>003.jpg</imageurl> 
 <navigateurl>003.aspx</navigateurl> 
 <impressions>30</impressions> 
 <keyword>gucas03</keyword> 
 </ad> 
 <ad> 
 <imageurl>004.jpg</imageurl> 
 <navigateurl>004.aspx</navigateurl> 
 <impressions>40</impressions> 
 <keyword>gucas04</keyword> 
 </ad> 
 <ad> 
 <imageurl>005.jpg</imageurl> 
 <navigateurl>005.aspx</navigateurl> 
 <impressions>50</impressions> 
 <keyword>gucas05</keyword> 
 </ad> 
 <ad> 
 <imageurl>google.gif</imageurl> 
 <navigateurl>http://www.google.com</navigateurl> 
 <impressions>30</impressions> 
 <keyword>google</keyword> 
 </ad> 
</advertisements> 

/// <summary> 
 /// 创建xml文件 
 /// </summary> 
 /// <param name="filename"></param> 
 public void createxmlfile(string filename) 
 { 
  xmldocument xmldoc = new xmldocument(); 
  xmlnode node; 
  node = xmldoc.createxmldeclaration("1.0", "utf-8", null); 
  xmldoc.appendchild(node); 
  xmlnode root = xmldoc.createelement("users"); 
  xmldoc.appendchild(root); 
  createnode(xmldoc, root, "username", "zhengyd"); 
  createnode(xmldoc, root, "email", "zhengyd@gucas.ac,cn"); 
  createnode(xmldoc, root, "url", "www.gucas.an,cn"); 
  createnode(xmldoc, root, "age", "27"); 
  try 
  { 
   xmldoc.save(server.mappath(filename)); 
   response.write("创建xml文件myxml.xml成功!"); 
  } 
  catch (exception ex) 
  { 
   response.write(ex.message); 
  } 
 } 
 /// <summary> 
 /// 写入xml文件 
 /// </summary> 
 /// <param name="file"></param> 
 public void writexmlfile(string file) 
 { 
  xmldocument xmdoc = new xmldocument(); 
  try 
  { 
   xmdoc.load(server.mappath(file)); 
   xmlnode root = xmdoc.selectsinglenode("advertisements"); 
   if (root != null) 
   { 
    xmlnode node = xmdoc.createnode(xmlnodetype.element, "ad", null); 
    createnode(xmdoc, node, "imageurl", "google.gif"); 
    createnode(xmdoc, node, "navigateurl", "http://www.google.com"); 
    createnode(xmdoc, node, "impressions", "30"); 
    createnode(xmdoc, node, "keyword", "google"); 
    root.appendchild(node); 
   } 
   xmdoc.save(server.mappath(file)); 
   response.write("写入xml文件xmlfile.xml成功。<br>"); 
  } 
  catch(exception ex) { 
   response.write(ex.message); 
  } 
 } 
 /// <summary> 
 /// 创建节点 
 /// </summary> 
 /// <param name="xmldoc"></param> 
 /// <param name="parentnode"></param> 
 /// <param name="name"></param> 
 /// <param name="value"></param> 
 public void createnode(xmldocument xmldoc, xmlnode parentnode, string name, string value) 
 { 
  xmlnode node = xmldoc.createnode(xmlnodetype.element, name, null); 
  node.innertext = value; 
  parentnode.appendchild(node); 
 } 
 /// <summary> 
 /// 读取xml文件 
 /// </summary> 
 /// <param name="file"></param> 
 private void readfile(string file) 
 { 
  xmldocument xmldoc = new xmldocument(); 
  try 
  { 
   xmldoc.load(server.mappath(file)); 
   xmlnode node = xmldoc.selectsinglenode("advertisements"); 
   if (node != null) 
   { 
    treenode root = new treenode(); 
    root.text = node.name; 
    tvxml.nodes.add(root); 
    foreach (xmlnode xnode in xmldoc.selectnodes("advertisements/ad")) 
    { 
     treenode tnode = new treenode(); 
     tnode.text = server.htmlencode("<" + xnode.name + ">"); 
     root.childnodes.add(tnode); 
      foreach (xmlnode xcnode in xnode.childnodes) 
      { 
       treenode tcnode = new treenode(); 
       tcnode.text = server.htmlencode("<" + xcnode.name + ">" + xcnode.innertext + "</" + xcnode.name + ">"); 
       tnode.childnodes.add(tcnode); 
      } 
     treenode ttnode = new treenode(); 
     ttnode.text = server.htmlencode("</" + xnode.name + ""); 
     root.childnodes.add(ttnode); 
    } 
    treenode tpnode = new treenode(); 
    tpnode.text = server.htmlencode("</" + node.name + ">"); 
    tvxml.nodes.add(tpnode); 
   } 
  } 
  catch (exception ex) 
  { 
   response.write(ex.message); 
  } 
 }