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}: 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
<?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 ( )
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