0606-工厂模式、单例模式、DBDA的单例和完整功能

工厂模式：只要指定类名，就可以据此获取一个该类的对象。

单例模式：某个类，只允许其“创建”出一个对象。

单例的方法：三私一公（一个私有化对象，一个私有化构造方法，一个私有化克隆方法，一个公共方法返回对象）。

DBDA类的单例模式和完整功能：

  1 <?php
  2 //$db = new mysqli('localhost:3306','root','','per_position');
  3 echo '<meta charset="utf-8">';
  4 class DBDA{
  5     //定义数据库链接参数
  6     public $host = 'localhost';
  7     public $user = 'root';
  8     public $pwd = '';
  9     public $database = 'per_position';
 10     public $charset = 'utf8';
 11     
 12     //数据库连接对象
 13     public $db = null;
 14     //DBDA对象
 15     private static $link = null;
 16     
 17     //禁止构造：初始化数据
 18     private function __construct($configArr=array()){
 19         $this->host = isset($configArr['host']) ? $configArr['host'] : 'localhost';
 20         $this->user = isset($configArr['user']) ? $configArr['user'] : 'root';
 21         $this->pwd = isset($configArr['pwd']) ? $configArr['pwd'] : '';
 22         $this->database = isset($configArr['database']) ? $configArr['database'] : 'per_position';
 23         $this->charset = isset($configArr['charset']) ? $configArr['charset'] : 'utf8';
 24         //链接数据库
 25         $this->connect();
 26     }
 27     //禁止克隆
 28     private function __clone(){}
 29     //提供公有方法返回对象
 30     static function getDb($config=array()){
 31         if(!isset(self::$link)){
 32             self::$link = new self($config);
 33         }
 34         return self::$link;
 35     }
 36     //链接数据库的方法
 37     function connect(){
 38         $this->db = new mysqli($this->host,$this->user,$this->pwd,$this->database);
 39         !mysqli_connect_error() or die('连接失败');
 40         $this->db->query('set names '.$this->charset);
 41     }
 42     //执行sql语句的方法
 43     function query($sql){
 44         $res = $this->db->query($sql);
 45         if(!$res){
 46             echo ("<br />执行失败。");
 47             echo "<br />失败的sql语句为：" . $sql;
 48             echo "<br />出错信息为：" . mysqli_error($this->db);
 49             echo "<br />错误代号为：" . mysqli_errno($this->db);
 50             die();
 51         }
 52         return $res;
 53     }
 54     //返回二维数组
 55     function getAll($sql){
 56         $res = $this->query($sql);
 57         return $res->fetch_all();
 58     }
 59     //返回字符串
 60     function getStr($sql){
 61         $res = $this->query($sql);
 62         $arr = $res->fetch_all();
 63         $str = '';
 64         foreach($arr as $v){
 65             foreach($v as $vv){
 66                 $str .= $vv.",";
 67             }
 68             $str = substr($str,0,-1);
 69             $str .= "^";
 70         }
 71         $str =  substr($str,0,-1);
 72         return $str;
 73     }
 74     //返回json
 75     function getJson($sql){
 76         $res = $this->query($sql);
 77         $arr = $res->fetch_all();
 78         return json_encode($arr);
 79     }
 80     //返回关联数组
 81     function getAssoc($sql){
 82         $res = $this->query($sql);
 83         $arr = array();
 84         while($row = $res->fetch_assoc()){
 85             $arr[$row['department']]=$row;
 86         }
 87         return $arr;
 88     }
 89 }
 90 //$config = array(
 91 //    //'database' => 'mysql'
 92 //);
 93 //$DBDA = new DBDA();
 94 //var_dump($DBDA->getJson('select * from user'));
 95 //看错误提示
 96 //$DBDA->query('select * from 123');
 97 //$res = $DBDA->db->query('select * from user');
 98 //var_dump($res->fetch_all());
 99 
100 
101 
102 //禁用了构造方法，直接new会报错。
103 //$DBDA = DBDA::getDb();
104 //var_dump($DBDA);
105 //echo "<br>";
106 //$DBDA = DBDA::getDb();
107 //var_dump($DBDA);

DBDA类的单例模式和完整功能

1 <?php
2 include('DBDA.class.php');
3 $dbda = DBDA::getDb();
4 var_dump($dbda->getAll('select * from user'));

类的引用