简单谈谈PHP面向对象之标识对象

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')}*/