PHP Development App Interface Learning notes and summary-app interface example [1]

Single-Case mode

The three principles of the singleton pattern:

The ① constructor needs to be marked as non-public (prevents external use of the new operator from being created), and the Singleton class cannot be instantiated in other classes, but only by itself.

② has a static member variable that holds an instance of the class $_instance

③ has a public static method that accesses this instance

Singleton mode (see PHP Singleton Pattern code snippet):

<?PHP/** Single case mode*/classdb{Static Private $_instance; Private function__construct () {}Static  Public functiongetinstance () {if(!self::$_instanceinstanceof Self) { Self::$_instance=NewSelf (); }        returnSelf::$_instance; }}

Single-instance mode connection database:

1<?PHP2 /*3 * Single-instance mode connection database4  */5 classdb{6     Static Private $_instance;//static member variables for instances of non-public classes7     Static Private $_connectsource;//the resource handle returned by the connection database8     Private $_dbconfig=Array(9' Host ' = ' 127.0.0.1 ',Ten' Username ' = ' root ', One' pwd ' = ', A' Database ' = ' chat ' -     ); -  the     Private function__construct () {//non-public constructors -     } -  -     Static  Public functionGetInstance () {//public static methods for accessing instances +         if(!self::$_instanceinstanceof Self) { -Self::$_instance=NewSelf (); +         } A         returnSelf::$_instance; at     } -  -      Public functionConnect () { -         if(!self::$_connectsource){ -             //Connect to MySQL service -Self::$_connectsource=mysql_connect($this->_dbconfig[' Host '],$this->_dbconfig[' username '),$this->_dbconfig[' pwd ']); in             if(!self::$_connectsource){ -                  die(' MySQL connect error '.Mysql_error()); to             } +             //Select Database -             mysql_select_db($this->_dbconfig[' database '],self::$_connectsource); the             //Set character sets *             mysql_query(' Set names ' UTF8 "', Self::$_connectsource); $         }Panax Notoginseng         returnSelf::$_connectsource;//Back to Resources -     } the } +  A $connect= Db::getinstance ()Connect (); the Var_dump($connect); +  - $sql= ' SELECT * from messages '; $ $res=mysql_query($sql,$connect); $ $num=mysql_num_rows($res); - Var_dump($num);

Page output:

Resource (3, mysql link)

int 2

PHP Development App Interface Learning notes and summary-app interface example [1]