create table 'venue' (   'id' int(11) not null auto_increment,   'name' text,   primary key ('id'))create table 'space' (   'id' int(11) not null auto_increment,   'venue' int(11) default null,   'name' text,   primary key ('id'))create table 'event' (   'id' int(11) not null auto_increment,   'space' int(11) default null,   'start' mediumtext,   'duration' int(11) default null,   'name' text,   primary key ('id'))

//領域模型(這里只建了一個Venue類用于理解)namespace woo/domain;abstract class DomainObject{      //抽象基類    private $id;    function __construct ($id=null){    $this->id = $id;  }    function getId(){    return $this->id;  }    //原書沒有具體實現，應該是用于獲取對象的從屬對象的，比如venue(場所)相關的space(空間)對象  //具體的代碼實現中應該從數據庫中查詢了相關數據并調用了Collection類，下面看到這個類的時候會有一個了解  //而且這個方法的實現應該放在子類中才對  static function getCollection($type){       return array();  }    function collection(){    return self::getCollection(get_class($this));  }  }class Venue extends DomainObject {  private $name;  private $spaces;    function __construct ($id = null,$name=null){    $this->name= $name;    $this->spaces = self::getCollection('//woo//domain//space'); //這里應該證明了我上述的猜測    parent::__construct($id);  }    function setSpaces(SpaceCollection $spaces){    $this->spaces = $spaces;  }    function addSpace(Space $space){    $this->spaces->add($space);    $space->setVenue($this);  }    function setName($name_s){    $this->name = $name_s;    $this->markDirty();  }    function getName(){    return $this->name;  }}//數據映射器(正如原文的解釋數據映射器是一個負責將數據庫數據映射到對象的類)namespace woo/mapper;abstract class Mapper{      //抽象基類  abstract static $PDO;    //操作數據庫的pdo對象  function __construct (){    if(!isset(self::$PDO){      $dsn = /woo/base/ApplicationRegistry::getDSN();      if(is_null($dsn)){        throw new /woo/base/AppException("no dns");      }      self::$PDO = new /PDO($dsn);      self::$PDO->setAttribute(/PDO::ATTR_ERRMODE,/PDO::ERRMODE_EXCEPTION);    }  }    function createObject($array){          //將數組創建為上述領域模型中的對象    $obj = $this->doCreateObject($array);    //在子類中實現    return $obj;  }    function find($id){                //通過ID從數據庫中獲取一條數據并創建為對象    $this->selectStmt()->execute(array($id));    $array= $this->selectStmt()->fetch();    $this->selectStmt()->closeCursor();    if(!is_array($array)){      return null;    }    if(!isset($array['id'])){      return null;    }    $object = $this->createObject($array);    return $object;    }    function insert(/woo/domain/DomainObject $obj){      //將對象數據插入數據庫    $this->doInsert($obj);  }    //需要在子類中實現的各抽象方法  abstract function update(/woo/domain/DomainObject $objet);  protected abstract function doCreateObject(array $array);  protected abstract function selectStmt();  protected abstract function doInsert(/woo/domain/DomainObject $object);}//這里只建立一個VenueMapper類用于理解class VenueMapper extends Mapper {  function __construct (){        parent::__construct();  //各種sql語句對象      $this->selectStmt = self::$PDO->prepare("select * from venue where id=?");    $this->updateStmt = self::$PDO->prepare("update venue set name=?,id=? where id=?");    $this->insertStmt = self::$PDO->prepare("insert into venue (name) values(?)");  }    protected function getCollection(array $raw){    //將Space數組轉換成對象    return new SpaceCollection($raw,$this);      //這個類的基類在下面      }    protected function doCreateObject (array $array){  //創建對象    $obj = new /woo/domain/Venue($array['id']);    $obj->setname($array['name']);    return $obj;  }    protected function doInsert(/woo/domain/DomainObject $object){ //將對象插入數據庫    print 'inserting';    debug_print_backtrace();    $values = array($object->getName());    $this->insertStmt->execute($values);    $id = self::$PDO->lastInsertId();    $object->setId($id);  }    function update(/woo/domain/DomainObject $object){    //修改數據庫數據    print "updation/n";    $values = array($object->getName(),$object->getId(),$object->getId());    $this->updateStmt->execute($values);  }    function selectStmt(){          //返回一個sql語句對象    return $this->selectStmt;  }  }

abstract class Collection implements /Iterator{  protected $mapper;      //數據映射器  protected $total = 0;    //集合元素總數量  protected $raw = array();  //原始數據    private $result;  private $pointer = 0;    //指針  private $objects = array();  //對象集合    function __construct (array $raw = null,Mapper $mapper= null){    if(!is_null($raw)&& !is_null($mapper)){      $this->raw = $raw;      $this->total = count($raw);    }    $this->mapper = $mapper;  }    function add(/woo/domain/DmainObject $object){  //這里是直接添加對象    $class = $this->targetClass();    if(!($object instanceof $class)){      throw new Exception("This is a {$class} collection");    }    $this->notifyAccess();    $this->objects[$this->total] = $object;    $this->total ++;  }    abstract function targetClass();  //子類中實現用來在插入對象時檢查類型的    protected function notifyAccess(){  //不知道干嘛的      }    private function getRow($num){    //獲取集合中的單條數據，就是這里通過數據映射器將數據創建成對象    $this->notifyAccess();    if($num >= $this->total || $num < 0){      return null;    }    if(isset($this->objects[$num]){      return $this->objects[$num];    }    if(isset($this->raw[$num]){      $this->objects[$num] = $this->mapper->createObject($this->raw[$num]);      return $this->objects[$num];    }  }    public function rewind(){      //重置指針    $this->pointer = 0;  }    public function current(){      //獲取當前指針對象    return $this->getRow($this->pointer);  }    public function key(){        //獲取當前指針    return $this->pointer;  }    public function next(){      //獲取當前指針對象,并將指針下移      $row = $this->getRow($this->pointer);    if($row){$this->pointer ++}    return $row;  }    public function valid(){    //驗證    return (!is_null($this->current()));  }  }//子類class VenueColletion extends Collection implements /woo/domain/VenueCollection{  function targetClass(){    return "/woo/domain/Venue";  }}//客戶端$mapper = new /woo/mapper/VenueMapper();$venue = $mapper->find(12);print_r($venue);$venue = new /woo/domain/Venue();$venue->setName("the likey lounge-yy");//插入對象到數據庫$mapper->insert($venue);//從數據庫中讀出剛才插入的對象$venue = $mapper->find($venue->getId());print_r($venue);//修改對象$venue->setName("the bibble beer likey lounge-yy");//調用update來更新記錄$mapper->update($venue);//再次讀出對象數據$venue = $mapper->find($venue->getId());print_r($venue);//結束