PHP面向对象之工作单元(实例讲解)

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