PHP实现动态添加XML中数据的方法

?php
  class Message_XML extends DomDocument{//定义类Message_XML并继承DomDocument类
   private $Root;
   public function __construct(){//构造函数
    parent:: __construct();
    if(!file_exists("message.xml")){//判断文件是否存在
     $xmlstr="?xml version='1.0' encoding='GB2312'?>message>/message>";
     $this->loadXML($xmlstr);
     $this->save("message.xml");//生成XML文档
    }else{
     $this->load("message.xml");//如果存在则载入XML文档
    }
   }
   public function add_message($user,$address){//创建方法
    $Root=$this->documentElement;//定义根节点
    $admin_id=date("Ynjhis");
    $Node_admin_id=$this->createElement("admin_id");//创建节点admin_id
    $text=$this->createTextNode(iconv("GB2312","UTF-8",$admin_id));//创建一个文本节点
    $Node_admin_id->appendChild($text);//将文本节点添加到admin_id节点中
    $Node_user=$this->createElement("user");//创建节点user
    $text=$this->createTextNode(iconv("GB2312","UTF-8",$user));//创建一个文本节点
    $Node_user->appendChild($text);//将文本节点添加到user节点中
    $Node_address=$this->createElement("address");//创建节点address
    $text=$this->createTextNode(iconv("GB2312","UTF-8",$address));//创建一个文本节点
    $Node_address->appendChild($text);//将文本节点添加到address节点中
    $Node_Record=$this->createElement("record");//创建节点record
    $Node_Record->appendChild($Node_admin_id);//将admin_id节点添加到record节点中
    $Node_Record->appendChild($Node_user);//将user节点添加到record节点中
    $Node_Record->appendChild($Node_address);//将address节点添加到record节点中
    $Root->appendChild($Node_Record);//将record节点添加到根节点中
    $this->save("message.xml");//生成XML文档
    echo "script>alert('添加成功');location.href='".$_SERVER['PHP_SELF']."'/script>";
   }
   public function show_message(){//定义输出XML文件中的内容函数
    $Root=$this->documentElement;//定义根节点
    $xpath=new DOMXPath($this);//定义DOMXPath
    $Node_Record=$this->getElementsByTagName("record");//获取节点record的标签
    $Node_Record_length=$Node_Record->length;//获取标签的数量
    print"table width='506' bgcolor='#FFFFCC'>tr>";
    print"td width='106' height='22' align='center'>";
    print"b>用户名/b>";
    print"/td>td width='400' align='center'>";
    print"b>留言信息/b>/td>/tr>";
    for($i=0;$i$Node_Record->length;$i++){//应用for循环输出查询结果
     $k=0;
     foreach($Node_Record->item($i)->childNodes as $articles){  //通过foreach语句读取返回对象中的数据
      $field[$k]=iconv("UTF-8","GB2312",$articles->textContent);//实现编码格式的转换
      $k++;
     }
     print"table width='506' bgcolor='#FFFFCC'>tr>";
     print"td width='106' height='22' align='center'>";
     print"$field[1]";
     print"/td>td width='400' align='center'>";
     print"$field[2]";
     print"/td>/tr>/table>";
    }
   }
   public function post_message(){//定义输出表单的函数
    print"table width='506' bgcolor='#FFFFCC'>form method='post' action='?Action=add_message'>";
    print"tr>td width='106' height='22'>nbsp;nbsp;nbsp;nbsp;用户名：/td>td>input type='text' name='user' size=50>/td>/tr>";
    print"tr>td width='106' height='22'>nbsp;nbsp;nbsp;nbsp;留言信息：/td>td width='400'>textarea name='address' cols='48' rows='5' id='address'>/textarea>/td>/tr>";
    print"tr>td width='106' height='30'>nbsp;nbsp;input type='submit' value='添加数据'>/td>td align='right'>a href='?Action=show_message'>查看数据/a>nbsp;nbsp;nbsp;nbsp;/td>/tr>/form>/table>";
   }
  }
?>
html>
head>
meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
title>添加XML数据/title>
style type="text/css">
!--
body,td,th {
  font-size: 12px;
}
-->
/style>/head>
body>
table width="506" height="50" border="0" cellpadding="0" cellspacing="0" bgcolor="#33BE6B">
 tr>
  td width="506" height="50" valign="bottom" background="title.gif">
   table width="506">
    tr>
     td height="24" align="right" scope="col">nbsp;nbsp;a href="?Action=post_message" rel="external nofollow" >添加数据/a>nbsp;nbsp;nbsp;/td>/tr>/table>/td>/tr>/table>
     ?php
      $HawkXML=new Message_XML;//实例化Message_XML类
      $Action="";//初始化为空值
      if(isset($_GET['Action'])) $Action=$_GET['Action'];
      switch($Action){
       case "show_message":
       $HawkXML->show_message();//当参数值为show_message时执行show_message()函数
       break;
       case "post_message":
       $HawkXML->post_message();//当参数值为post_message时执行post_message()函数
       break;
       case "add_message":
       $HawkXML->add_message($_POST['user'],$_POST['address']);//当参数值为add_message时执行add_message()函数
       break;
      }
     ?>
/body>
/html>