PHP面向对象程序设计之对象生成方法详解

　　本文实例讲述了PHP面向对象程序设计之对象生成方法。分享给大家供大家参考，具体如下：

　　对象

　　看个例子

　　 <?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}: Ill 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: Ill 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}: Ill 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}: Ill 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: Ill clear my desk // bob: Ill call my lawyer // harry: Ill 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

　　 <?php // 根据类图，规划类的代码。从大局入手。 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 { const APPT = 1; const TTD = 2; const CONTACT = 3; abstract function getHeaderText(); abstract function make( $flag_int ); // int标记 abstract function getFooterText(); } class BloggsCommsManager extends CommsManager { function getHeaderText() { return BloggsCal header\n; } function make( $flag_int ) { switch ( $flag_int ) { case self::APPT: // self直接控制常量 return new BloggsApptEncoder(); case self::CONTACT: return new BloggsContactEncoder(); case self::TTD: return new BloggsTtdEncoder(); } } function getFooterText() { return BloggsCal footer\n; } } $mgr = new BloggsCommsManager(); print $mgr->getHeaderText(); print $mgr->make( CommsManager::APPT )->encode(); print $mgr->getFooterText(); ?>

　　output:

　　BloggsCal header
Appointment data encoded in BloggsCal format
BloggsCal footer

　　原型模式

　　改造成一个保存具体产品的工厂类。

　　 <?php class Sea {} // 大海 class EarthSea extends Sea {} class MarsSea extends Sea {} class Plains {} // 平原 class EarthPlains extends Plains {} class MarsPlains extends Plains {} class Forest {} // 森林 class EarthForest extends Forest {} class MarsForest extends Forest {} class TerrainFactory { // 地域工厂 private $sea; private $forest; private $plains; function __construct( Sea $sea, Plains $plains, Forest $forest ) { // 定义变量为类对象 $this->sea = $sea; $this->plains = $plains; $this->forest = $forest; } function getSea( ) { return clone $this->sea; // 克隆 } function getPlains( ) { return clone $this->plains; } function getForest( ) { return clone $this->forest; } } $factory = new TerrainFactory( new EarthSea(), new EarthPlains(), new EarthForest() ); print_r( $factory->getSea() ); print_r( $factory->getPlains() ); print_r( $factory->getForest() ); ?>

　　output:

　　 EarthSea Object ( ) EarthPlains Object ( ) EarthForest Object ( )

　　更多关于PHP相关内容感兴趣的读者可查看本站专题：《php面向对象程序设计入门教程》、《PHP基本语法入门教程》、《PHP运算与运算符用法总结》、《PHP网络编程技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》

　　希望本文所述对大家PHP程序设计有所帮助。