PHP ORM 实现

<?phpabstractclass Model{   protected$pk = 'id';   protected$_ID = null;    protected$_tableName;   protected$_arRelationMap;   protected$_modifyMap;   protected$is_load = false;   protected$_blForDeletion;   protected$_DB;   publicfunction __consturct($id = null){       $this->_DB = mysql_connect('127.0.0.1','root','') ;       $this->_tableName = $this->getTableName();       $this->_arRelationMap = $this->getRelationMap();       if(isset($id))$this->_ID = $id;   }   abstractprotectedfunction getTableName();   abstractprotectedfunction getRelationMap();   publicfunction Load(){       if(isset($this->_ID)){           $sql = "SELECT ";           foreach($this->_arRelationMap as$k => $v){               $sql .= '`'.$k.'`,';           }           $sql .= substr($sql,0,strlen($sql)-1);           $sql .= "FROM ".$this->_tableName." WHERE ".$this->pk." = ".$this->_ID;           $result =$this->_DB->mysql_query($sql);           foreach($result[0] as$k1 => $v1){              $member = $this->_arRelationMap[$key];              if(property_exists($this,$member)){                 if(is_numeric($member)){                     eval('$this->'.$member.' = '.$value.';');                 }else{                     eval('$this->'.$member.' = "'.$value.'";');                 }              }           }       }       $this->is_load = true;   }   publicfunction __call($method,$param){      $type   = substr($method,0,3);      $member = substr($method,3);      switch($type){         case 'get':             return$this->getMember($member);             break;         case 'set':             return$this->setMember($member,$param[0]);      }      returnfalse;   }   publicfunction setMember($key){       if(property_exists($this,$key)){          if(is_numeric($val)){             eval('$this->'.$key.' = '.$val.';');          }else{             eval('$this->'.$key.' = "'.$val.'";');          }          $this->_modifyMap[$key] = 1;       }else{          returnfalse;       }   }      publicfunction getMember($key,$val){       if(!$this->is_load){          $this->Load();       }       if(property_exists($this,$key)){          eval('$res = $this->'.$key.';' );          return$this->$key;       }       returnfalse;   }   publicfunction save(){      if(isset($this->_ID)){          $sql = "UPDATE ".$this->_tableName." SET ";          foreach($this->arRelationMap as$k2 => $v2){              if(array_key_exists( $k2, $this->_modifyMap)){                  eval( '$val = $this->'.$v2.';');                  $sql_update .=  $v2." = ".$val;              }          }          $sql .= substr($sql_update,0,strlen($sql_update));          $sql .= 'WHERE '.$this->pk.' = '.$this->_ID;      }else{          $sql = "INSERT INTO ".$this->_tableName." (";          foreach($this->arRelationMap as$k3 => $v3){              if(array_key_exists( $k3,$this->_modifyMap)){                  eval('$val = $this->'.$v3.';');                  $field  .= "`".$v3."`,";                   $values .= $val;              }          }          $fields = substr($field,0,strlen($field)-1);          $vals   = substr($values,0,strlen($values)-1);          $sql .= $fields." ) VALUES (".$vals.")";      }      echo$sql;      //$this->_DB->query($sql);   }   publicfunction __destory(){      if(isset($this->ID)){         $sql = "DELETE FROM ".$this->_tableName." WHERE ".$this->pk." = ".$this->_ID;        // $this->_DB_query($sql);      }   }}class User extends Model{    protectedfunction getTableName(){       return "test_user";    }    protectedfunction getRelationMap(){        returnarray(                       'id'       => USER_ID,                      'user_name'=> USER_NAME,                      'user_age' => USER_AGE                    );    }    publicfunction getDB(){       return$this->_DB;    }}$UserIns = new User();print_r($UserIns);?>