PHP面向对象之标识对象的实例讲解

/*标识对象模式
这个模式主要功能就是创建sql语句中的wehre条件字符串的，下面直接看代码和注释:*/namespace woo\mapper;//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class IdentityObject {protected $currentfield = null;        //当前操作的字段对象protected $fields = array();        //字段集合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 $ret;
    }
}//客户端代码$idobj = new IdentityObject ();$idobj->field("name")->eq("The Good Show")->field("start")->gt(time())->lt(time()+(24*60*60));$test = $idobj->getComps();var_dump($test);//输出类似下面的内容/*array{
    array('name'=>'name','operator'=>'=','value'=>'The Good Show'),
    array('name'=>'start','operator'=>'>','value'=>'123456'),   //123456表示time()函数输出的时间戳
    array('name'=>'start','operator'=>'<','value'=>'123456')
}*/