PHP面向对象之工作单元(实例讲解)

namespace woo/domain;//标识映射class ObjectWatcher{    private $all = array();        //存放对象的小仓库  private $dirty = array();      //存放需要在数据库中修改的对象  private $new = array();        //存放需要在数据库中新增的对象  private $delete = array();      //存放需要在数据库中删除的对象  private static $instance;      //单例      private function __construct (){}    static function instance(){    if(!self::$instance){      self::$instance = new ObjectWatcher();    }    return self::$instance;  }    //获取一个唯一的标识,这里采用了领域类类名+ID的方式创建一个唯一标识，避免多个数据库表调用这个类时出现ID重复的问题  function globalKey(DomainObject $obj){    $key = get_class($obj) . "." . $obj->getId();    return $key;  }    //添加对象  static function add(DomainObject $obj){    $inst = self::instance();    $inst->all[$inst->globalKey($obj)] = $obj;  }    //获取对象  static function exists($classname,$id){    $inst = self::instance();    $key = "$classname.$id";    if(isset($inst->all[$key]){      return $inst->all[$key];    }    return null;  }    //标记为需要删除的对象  static function addDelete(DomainObject $obj){    $self = self::instance();    $self->delete[$self->globalKey($obj)] = $obj;  }    //标记为需要修改的对象  static function addDirty(DomainObject $obj){    $inst = self::instance();    if(!in_array($obj,$inst->new,true)){      $inst->dirty[$inst->globalKey($obj)] = $obj;    }  }    //标记为需要新增的对象  static function addNew(DomainObject $obj){    $inst = self::instance();    $inst->new[] = $obj;  }    //标记为干净的对象  static function addClean(DomainObject $obj){    $self = self::instance();    unset($self->delete[$self->globalKey($obj)]);    unset($self->dirty[$self->globalKey($obj)]);    $self->new = array_filter($self->new,function($a) use($obj) {return !($a === $obj);});  }      //将上述需要增删改的对象与数据库交互进行处理    function performOperations(){    foreach($this->dirty as $key=>$obj){      $obj->finder()->update($obj);    //$obj->finder()获取一个数据映射器    }    foreach($this->new as $key=>$obj){      $obj->finder()->insert($obj);    }    $this->dirty = array();    $this->new = array();  }}//领域模型abstract class DomainObject{      //抽象基类    private $id = -1;    function __construct ($id=null){    if(is_null($id)){      $this->markNew();      //初始化时即被标记为需要新增的对象了    } else {      $this->id = $id;    }    }    //调用了标识映射的标记对象的方法  function markNew(){    ObjectWatcher::addNew($this);  }    function markDeleted(){    ObjectWatcher::addDelete($this);  }    function markDirty(){    ObjectWatcher::addDirty($this);  }    function markClean(){    ObjectWatcher::addClean($this);  }    function setId($id){    $this->id = $id;  }    function getId(){    return $this->id;  }      function finder(){    return self::getFinder(get_class($this));  }    //通过工厂类来实例化一个特定类型的数据映射器对象，例如VenueMapper  //这个对象将被标识映射器中的performOperations方法调用用于与数据库交互进行增删改的操作  static function getFinder($type){    return HelperFactory::getFinder($type);  }  }class Venue extends DomainObject {  private $name;  private $spaces;    function __construct ($id = null,$name=null){    $this->name= $name;    $this->spaces = self::getCollection('//woo//domain//space');     parent::__construct($id);  }    function setSpaces(SpaceCollection $spaces){    $this->spaces = $spaces;    $this->markDirty();            //标记为需要修改的对象  }    function addSpace(Space $space){    $this->spaces->add($space);    $space->setVenue($this);    $this->markDirty();            //标记为需要修改的对象  }    function setName($name_s){    $this->name = $name_s;    $this->markDirty();            //标记为需要修改的对象  }    function getName(){    return $this->name;  }}//领域模型class Space extends DomainObject{  //.........  function setName($name_s){    $this->name = $name_s;    $this->markDirty();  }    function setVenue(Venue $venue){    $this->venue = $venue;    $this->markDirty();  }}//数据映射器abstract class Mapper{    abstract static $PDO;    //操作数据库的pdo对象  function __construct (){    if(!isset(self::$PDO){      $dsn = /woo/base/ApplicationRegistry::getDSN();      if(is_null($dsn)){        throw new /woo/base/AppException("no dns");      }      self::$PDO = new /PDO($dsn);      self::$PDO->setAttribute(/PDO::ATTR_ERRMODE,/PDO::ERRMODE_EXCEPTION);    }  }    //获取标记的对象  private function getFroMap($id){    return /woo/domain/ObjectWatcher::exists($this->targetClass(),$id);  }      //新增标记的对象  private function addToMap(/woo/domain/DomainObject $obj){//////    return /woo/domain/ObjectWatcher::add($obj);  }      //将数据库数据映射为对象  function createObject($array){    $old = $this->getFromMap($array['id']);    if($old){return $old;}    $obj = $this->doCreateObject($array);    $this->addToMap($obj);    $obj->markClean();    return $obj;  }    function find($id){                //通过ID从数据库中获取一条数据并创建为对象      $old = $this->getFromMap($id);            if($old){return $old}                    $this->selectStmt()->execute(array($id));    $array= $this->selectStmt()->fetch();    $this->selectStmt()->closeCursor();    if(!is_array($array)){      return null;    }    if(!isset($array['id'])){      return null;    }    $object = $this->createObject($array);    $this->addToMap($object);              return $object;    }      function insert(/woo/domain/DomainObject $obj){      //将对象数据插入数据库    $this->doInsert($obj);    $this->addToMap($obj);              }    //需要在子类中实现的各个抽象方法  abstract function targetClass();                    //获取类的类型  abstract function update(/woo/domain/DomainObject $objet);        //修改操作  protected abstract function doCreateObject(array $array);        //创建对象  protected abstract function selectStmt();                //查询操作  protected abstract function doInsert(/woo/domain/DomainObject $object);  //插入操作  }class VenueMapper extends Mapper {  function __construct (){        parent::__construct();      //预处理对象    $this->selectStmt = self::$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 $raw){    //将Space数组转换成对象集合    return new SpaceCollection($raw,$this);          }    protected function doCreateObject (array $array){  //创建对象    $obj = new /woo/domain/Venue($array['id']);    $obj->setname($array['name']);    return $obj;  }    protected function doInsert(/woo/domain/DomainObject $object){ //将对象插入数据库    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){    //修改数据库数据    print "updation/n";    $values = array($object->getName(),$object->getId(),$object->getId());    $this->updateStmt->execute($values);  }    function selectStmt(){          //返回一个预处理对象    return $this->selectStmt;  }  }//客户端$venue = new /woo/domain/Venue(null,"The Green Tree");        //在初始化时就被标记为新增对象了$venue->addSpace(new /woo/domain/Space(null,"The Space Upstairs"));  //这二行addSpace方法因为venue已经被标记新增所以不会再标记为修改对象,但是space在初始化的时候会被标记为新增对象$venue->addSpace(new /woo/domain/Space(null,"The Bar Stage"));　　　　　　/woo/domain/ObjectWatcher::instance()->performOperations();      //与数据库交互新增一条Venue数据,以及二条space数据