<?php abstract class Employee { // 雇员 protected $name; function __construct( $name ) { $this->name = $name; } abstract function fire(); } class Minion extends Employee { // 奴隶 继承 雇员 function fire() { print "{$this->name}: I'll clear my desk\n"; } } class NastyBoss { // 坏老板 private $employees = array(); function addEmployee( $employeeName ) { // 添加员工 $this->employees[] = new Minion( $employeeName ); // 代码灵活性受到限制 } function projectFails() { if ( count( $this->employees ) > 0 ) { $emp = array_pop( $this->employees ); $emp->fire(); // 炒鱿鱼 } } } $boss = new NastyBoss(); $boss->addEmployee( "harry" ); $boss->addEmployee( "bob" ); $boss->addEmployee( "mary" ); $boss->projectFails(); // output: // mary: I'll clear my desk ?>
再看一个更具有灵活性的案例
<?php abstract class Employee { protected $name; function __construct( $name ) { $this->name = $name; } abstract function fire(); } class Minion extends Employee { function fire() { print "{$this->name}: I'll clear my desk\n"; } } class NastyBoss { private $employees = array(); function addEmployee( Employee $employee ) { // 传入对象 $this->employees[] = $employee; } function projectFails() { if ( count( $this->employees ) ) { $emp = array_pop( $this->employees ); $emp->fire(); } } } // new Employee class... class CluedUp extends Employee { function fire() { print "{$this->name}: I'll call my lawyer\n"; } } $boss = new NastyBoss(); $boss->addEmployee( new Minion( "harry" ) ); // 直接以对象作为参数，更具有灵活性 $boss->addEmployee( new CluedUp( "bob" ) ); $boss->addEmployee( new Minion( "mary" ) ); $boss->projectFails(); $boss->projectFails(); $boss->projectFails(); // output: // mary: I'll clear my desk // bob: I'll call my lawyer // harry: I'll clear my desk ?>
单例
<?php class Preferences { private $props = array(); private static $instance; // 私有的，静态属性 private function __construct() { } // 无法实例化，私有的构造函数 public static function getInstance() { // 返回对象 静态方法才可以被类访问，静态方法中要有静态属性 if ( empty( self::$instance ) ) { self::$instance = new Preferences(); } return self::$instance; } public function setProperty( $key, $val ) { $this->props[$key] = $val; } public function getProperty( $key ) { return $this->props[$key]; } } $pref = Preferences::getInstance(); $pref->setProperty( "name", "matt" ); unset( $pref ); // remove the reference $pref2 = Preferences::getInstance(); print $pref2->getProperty( "name" ) ."\n"; // demonstrate value is not lost ?>
点评：不能随意创建对象，只能通过Preferences::getInstance()来创建对象。
工厂模式
<?php abstract class ApptEncoder { abstract function encode(); } class BloggsApptEncoder extends ApptEncoder { function encode() { return "Appointment data encoded in BloggsCal format\n"; } } class MegaApptEncoder extends ApptEncoder { function encode() { return "Appointment data encoded in MegaCal format\n"; } } class CommsManager { // 负责生产Bloggs对象 function getApptEncoder() { return new BloggsApptEncoder(); } } $obj = new CommsManager(); $bloggs = $obj->getApptEncoder(); // 获取对象 print $bloggs->encode(); ?>
output:
Appointment data encoded in BloggsCal format
进一步增加灵活性设置
<?php abstract class ApptEncoder { abstract function encode(); } class BloggsApptEncoder extends ApptEncoder { function encode() { return "Appointment data encoded in BloggsCal format\n"; } } class MegaApptEncoder extends ApptEncoder { function encode() { return "Appointment data encoded in MegaCal format\n"; } } class CommsManager { const BLOGGS = 1; const MEGA = 2; private $mode ; function __construct( $mode ) { $this->mode = $mode; } function getHeaderText() { switch ( $this->mode ) { case ( self::MEGA ): return "MegaCal header\n"; default: return "BloggsCal header\n"; } } function getApptEncoder() { switch ( $this->mode ) { case ( self::MEGA ): return new MegaApptEncoder(); default: return new BloggsApptEncoder(); } } } $man = new CommsManager( CommsManager::MEGA ); print ( get_class( $man->getApptEncoder() ) )."\n"; $man = new CommsManager( CommsManager::BLOGGS ); print ( get_class( $man->getApptEncoder() ) )."\n"; ?>
output:
MegaApptEncoder
BloggsApptEncoder
工厂方法模式要把创建者类与要生产的产品类分离开来。
抽象工厂
通过抽象来来约束，成为一定的规矩。
<?php abstract class ApptEncoder { abstract function encode(); } class BloggsApptEncoder extends ApptEncoder { function encode() { return "Appointment data encoded in BloggsCal format\n"; } } class MegaApptEncoder extends ApptEncoder { function encode() { return "Appointment data encoded in MegaCal format\n"; } } abstract class CommsManager { // 预约 abstract function getHeaderText(); abstract function getApptEncoder(); abstract function getTtdEncoder(); abstract function getContactEncoder(); abstract function getFooterText(); } class BloggsCommsManager extends CommsManager { function getHeaderText() { return "BloggsCal header\n"; } function getApptEncoder() { return new BloggsApptEncoder(); } function getTtdEncoder() { return new BloggsTtdEncoder(); } function getContactEncoder() { return new BloggsContactEncoder(); } function getFooterText() { return "BloggsCal footer\n"; } } class MegaCommsManager extends CommsManager { function getHeaderText() { return "MegaCal header\n"; } function getApptEncoder() { return new MegaApptEncoder(); } function getTtdEncoder() { return new MegaTtdEncoder(); } function getContactEncoder() { return new MegaContactEncoder(); } function getFooterText() { return "MegaCal footer\n"; } } $mgr = new MegaCommsManager(); print $mgr->getHeaderText(); print $mgr->getApptEncoder()->encode(); // 对象调用方法，返回对象，继续调用方法。 print $mgr->getFooterText(); ?>
output:
MegaCal header
Appointment data encoded in MegaCal format
MegaCal footer
更加牛逼的实现