php面向对象中的选择工厂以及更新工厂的代码示例分享

选择工厂和更新工厂模式,这个模式的类(UpdateFactory和SelectionFactory类)就是用来创建SQL语句的.

因为涉及到之前学习的内容比较多,这里就尽量将之前相关模式的示例代码放在一起来进行学习和回顾了。

以下的代码都是代码片段而且涉及到连接数据库,无法进行整体的调试(某些部分单独拿出来的话就可以),因此重在理解。

//更新工厂 abstract class UpdateFactory{ abstract function newUpdate(\woo\domain\DomainObject $obj); //拼接更新或插入的sql语句 protected function buildStatement($table,array $fields ,array $condition = null){ $terms = array(); //SQL语句中占位符所代表的实际值 if(!is_null($condition)){ //有条件则拼接更新语句,无条件则拼接插入语句 $query = "UPDATE {$table} SET"; $query .= implode(" = ? " ,array_keys($fields)) . " = ? "; $terms = array_values($fields); $cond = array(); $query .= " WHERE "; foreach($condition as $key=>$val){ $cond[] = " $key = ? "; $terms[] = $val; } $query .= implode(" AND ",$cond); } else { $query = " INSERT INTO {$table} ("; $query .= implode(",",array_keys($fields)); $query .= " ) VALUES ( "; foreach($fields as $name => $value){ $terms[] = $value; $qs[] = "?"; } $query .= implode(",",$qs); $query .=" ) "; } return array($query,$terms); } } //通过领域模型生成SQL语句 class VenueUpdateFactory extends UpdateFactory{ function newUpdate(\woo\domain\DomainObject $obj){ $id = $obj->getId(); $cond = null; $values['name'] = $obj->getName(); if($id > -1 ){ $cond["id"] = $id; } return $this->buildStatement("venue",$values,$cond); } } //选择工厂 abstract class SelectionFactory{ abstract function newSelection(IdentityObject $obj); //通过标识对象拼接sql语句的where条件语句 function buildWhere (IdentityObject $obj){ if($obj->isVoid){ return array("",array()); } $compstrings = array(); $values = array(); foreach($obj->getComps() as $comp){ $compstrings[] = "{$comp['name']} {$comp['operator']} ?"; $values[] = $comp['value']; } $where = " WHERE " . implode(" AND ",$compstrings); return array($where,$values); } } //拼接select语句 class VenuSelectionFactory extends SelectionFactory { function newSelection(IdentityObject $obj){ $field = implode(',',$obj->getObjectFields()); $core = "SELECT $fields FROM venue"; list($where,$values) = $this->buildWhere($obj); return array($core." ".$where,$values); } } //现在来回顾一下之前学习过的相关知识 //字段对象 class Field { protected $name = null; //字段名称 protected $operator = null; //操作符 protected $comps = array(); //存放条件的数组 protected $incomplete = false; //检查条件数组是否有值 function __construct ($name){ $this->name= $name; } //添加where 条件 function addTest($operator,$value){ $this->comps[] = array('name'=>$this->name,'operator'=>$operator,'value'=>$value); } //获取存放条件的数组 function getComps(){ return $this->comps; } function isIncomplete(){ return empty($this->comps); } } //标识对象,主要功能就是拼接where条件语句 class IdentityObject { protected $currentfield = null; //当前操作的字段对象 protected $fields = array(); //字段对象集合 private $and = null; private $enforce = array(); //限定的合法字段 function __construct($field = null, array $enforce = null){ if(!is_null($enforce)){ $this->enforce = $enforce; } if(!is_null($field)){ $this->field($field); } } //获取限定的合法字段 function getObjectFields(){ return $this->enforce; } //主要功能为设置当前需要操作的字段对象 function field($fieldname){ if(!$this->isVoid()&& $this->currentfield->isIncomplete()){ throw new \Exception("Incomplete field"); } $this->enforceField($fieldname); if(isset($this->fields[$fieldname]){ $this->currentfield = $this->fields[$fieldname]; } else { $this->currentfield = new Field($fieldname); $this->fields[$fieldname] = $this->currentfield; } return $this; //采用连贯语法 } //字段集合是否为空 function isVoid(){ return empty($this->fields); } //检查字段是否合法 function enforceField ($fieldname){ if(!in_array($fieldname,$this->enforce) && !empty($this->enforce)){ $forcelist = implode(',',$this->enforce); throw new \Exception("{$fieldname} not a legal field {$forcelist}"); } } //向字段对象添加where条件 function eq($value){ return $this->operator("=",$value); } function lt($value){ return $this->operator("<",$value); } function gt($value){ return $this->operator(">",$value); } //向字段对象添加where条件 private function operator($symbol,$value){ if($this->isVoid){ throw new \Exception("no object field defined"); } $this->currentfield->addTest($symbol,$value); return $this; //采用连贯语法 } //获取此类中所有字段对象集合的where条件数组 function getComps(){ $ret = array(); foreach($this->fields as $key => $field){ $ret = array_merge($ret,$field->getComps()); } return $ret; } } //数据映射器 class DomainObjectAssembler { protected static $PDO; //PersistenceFactory本例中并未实现,按原书的说法读者自己完成 //其主要功能就是生成相应类型的选择工厂类、更新工厂类或Collection对象 //在初始化的时候根据传入的PersistenceFactory对象决定了这个类是映射那个数据库表和领域模型的 function __construct (PersistenceFactory $factory){ $this->factory = $factory; if(!isset(self::$PDO)){ $dsn = \woo\base\ApplicationRegistry::getDSN(); if(is_null($dsn)){ throw new \woo\base\AppException("NO DSN"); } self::$PDO = new \PDO ($dsn); self::$PDO->setAttribute(\PDO::ATTR_ERRMODE,\PDO::ERRMODE_EXCEPTION); } } //获取预处理对象,用sql语句本身做为对象数组的键 function getStatement($str){ if(!isset($this->statements[$str])){ $this->statements[$str] = self::$PDO->prepare($str); } return $this->statements[$str]; } //根据where条件返回一条数据 function findOne(IdentityObject $idobj){ $collection = $this->find($idobj); return $collection->next(); } //根据where条件返回一个数据集合 function find(IdentityObject $idobj){ $selfact = $this->factory->getSelectionFactory(); //获取选择工厂对象 list($selection,$values) = $selfact->newSelection($idobj); //获取sql语句 $stmt = $this->getStatement($selection); //获取预处理对象 $stmt->execute($values); $raw = $stmt->fetchAll(); return $this->factory->getCollection($raw); //还记得Collection对象吗,下面粘出代码回顾一下 } //根据where条件插入或更新一条数据 function insert(\woo\domain\DomainObject $obj){ $upfact = $this->factory->getUpdateFactory(); //获取更新工厂对象 list($update,$values) = $upfact->newUpdate($obj); //获取sql语句 $stmt = $this->getStatement($update); //获取预处理对象 $stmt->execute($values); if($obj->getId()<0){ $obj->setId(self::$PDO->lastInsertId); } $obj->markClean(); } }

这里在回顾一下Collection类,当然这个类和上面使用的Collection类是有差别的,因为至少这里的Mapper类与之前相比发生了一些变化

Iterator接口定义的方法:

rewind() 指向列表开头 current() 返回当前指针处的元素 key() 返回当前的键(比如,指针的指) next() valid()