PHP Common Design Patterns

• Singleton mode (ensures that a class is instantiated only once and can be instantiated by itself)
• Factory mode (replaces the new operation)
• Strategy mode (use different methods to achieve the same purpose)
• Observer mode (When an object changes, other objects also trigger the corresponding action)
• Adapter mode (encapsulates different methods into a unified approach)
• Registration mode (putting an instance into an array for invocation)

These design patterns are useful in common PHP frameworks: thinkphp, Yii2, and so on.

 /* * * Singleton mode * Ensure that there is only one instance of this class and can instantiate it by itself * used in: Database operations, log objects, etc. */class single{public $db = NULL;    static $instance = null;        Public Function __construct () {$this->db = new mysqli (' 127.0.0.1 ', ' root ', ' root ', ' test ');        if ($this->db->connect_error) {die (' Connect error: '. $this->db->connect_error);    } echo "MySQL connect successful\n"; } static Public Function getinstance () {if (!) (            Self:: $instance instanceof Self)} {self:: $instance = new self ();        echo "aaa\n";        } echo "bbb\n";    Return self:: $instance;    Public Function __destruct () {$this->db->close (); }}single::getinstance (); single::getinstance ();//output:/* MySQL connect successful AAA BBB bbb*/ 

 /** * Factory mode * Use Factory method instead of a mode of new operation */interface people{public function Say ();}    Class Man implements people{public function say () {echo ' I am man \ n ';    }}class woman implements people{public function say () {echo "I am woman \ n";    }}class factory{Public Function Createman () {Return to New Man ();    } public Function Createwoman () {return new woman (); }} $f = new factory (), $f->createman ()->say (), $f->createwoman ()->say (),//output//I am man I am woman */ 

 /** * Strategy mode [use different ways to achieve the same purpose] * scene: Take different means of transport to the company */abstract Class tools{abstract function working ();} Class Bicyle extends tools{public Function working () {echo __method__.    "\ n"; }}class Car extends tools{public Function working () {echo __method__.    "\ n";    }}class transport{Public Function running ($obj) {$obj->working (); }/** * Use magic Method can also achieve the above effect * @param type $name * @param type $arguments */Public function __call ($name    , $arguments) {$arguments [0]-> $name (); }} $t = new transport (), $t->running (New Car ()), $t->running (New Bicyle ()), $t->working (New Car ());// The above effects can also be achieved using the Magic method//Output//car::working bicyle::working car::working */ 

 /* Observer mode * When an object state changes, all objects that depend on it receive a trigger action * occurrence scene: Yii2 's behavior,event */interface event{function Run ();} Class E1 implements event{Public function run () {echo __method__.    "\ n"; }}class E2 implements event{Public function run () {echo __method__.    "\ n";        }}class observer{static $obs;    function Addobs ($name, $obj) {self:: $obs [$name] = $obj;        } function trigger () {foreach (self:: $obs as $val) {$val->run (); }}} $o = new observer (), $o->addobs (' E1 ', New E1 ()), $o->addobs (' E2 ', New E2 ()), $o->trigger ();//output//E1::run E2: : Run */ 

 /* * Adapter Mode * Encapsulates different methods into a unified method for invocation * used in database MySQL, mysqli, PDO, etc. */interface db{public function connect ();    Public function query (); Public function Close ();}        Class Mysqla implements db{public $db;    Public Function Connect () {$this->db = Mysqli_connect ($host, $user, $password, $database, $port, $socket);    Public Function query () {} public Function close () {mysqli_close ($this->db);        }}class MYSQLB implements db{public $db;    Public Function Connect () {$this->db = new PDO ($DSN, $username, $password);    Public Function query () {} public Function close () {$this->db = null; }}

/*  * 注册模式 * 把已有对象放入一个数组里以供调用 */class register{    static $objects;        public static function set($name, $obj){        self::$objects[$name] = $obj;    }    public static function get($name){        return self::$objects[$name];    }}class log{};register::set(‘log‘, new log());$log = register::get(‘log‘);

PHP Common Design Patterns