PHP creates linked lists and adds, deletes, updates and traverses linked list nodes

<?php
/**
 * @author MzXy
 * @copyright 2011
 * @param PHP链表
 */
/**
*
*节点类
*/
class Node
{
  private $Data;//节点数据
  private $Next;//下一节点
  public function setData($value){
    $this->Data=$value;
  }
  public function setNext($value){
     $this->Next=$value;
  }  
  public function getData(){
    return $this->Data;
  }
  public function getNext(){
    return $this->Next;
  }
  public function __construct($data,$next){
    $this->setData($data);
    $this->setNext($next);
  }
}//功能类
class LinkList
{
  private $header;//头节点
  private $size;//长度
  public function getSize(){
    $i=0;
    $node=$this->header;
    while($node->getNext()!=null)
    {  $i++;
      $node=$node->getNext();
    }
   return $i;
  }
  public function setHeader($value){
    $this->header=$value;
  }
  public function getHeader(){
    return $this->header;
  }
  public function __construct(){
     header("content-type:text/html; charset=utf-8");
    $this->setHeader(new Node(null,null));
  }
  /**
  *@author MzXy
  *@param $data--要添加节点的数据
  * 
  */
  public function add($data)
  {
    $node=$this->header;
    while($node->getNext()!=null)
    {
      $node=$node->getNext();
    }
    $node->setNext(new Node($data,null));
  }
   /**
  *@author MzXy
  *@param $data--要移除节点的数据
  * 
  */
  public function removeAt($data)
  {
    $node=$this->header;
    while($node->getData()!=$data)
    {
      $node=$node->getNext();
    }
    $node->setNext($node->getNext());
    $node->setData($node->getNext()->getData());
  }
   /**
  *@author MzXy
  *@param 遍历
  * 
  */
  public function get()
  {
    $node=$this->header;
    if($node->getNext()==null){
      print("数据集为空!");
      return;
    }
    while($node->getNext()!=null)
    {
      print($node->getNext()->getData());
      if($node->getNext()->getNext()==null){break;}
      $node=$node->getNext();
    }
  }
   /**
  *@author MzXy
  *@param $data--要访问的节点的数据
  * @param 此方法只是演示不具有实际意义
  * 
  */
  public function getAt($data)
  {
    $node=$this->header->getNext();
     if($node->getNext()==null){
      print("数据集为空!");
      return;
    }
    while($node->getData()!=$data)
    {
      if($node->getNext()==null){break;}
      $node=$node->getNext();
    }
    return $node->getData();    
  }
   /**
  *@author MzXy
  *@param $value--需要更新的节点的原数据 --$initial---更新后的数据
  * 
  */
  public function update($initial,$value)
  {
     $node=$this->header->getNext();
     if($node->getNext()==null){
      print("数据集为空!");
      return;
    }
    while($node->getData()!=$data)
    {
      if($node->getNext()==null){break;}
      $node=$node->getNext();
    }
     $node->setData($initial);   
  }
}
?>