PHP面向对象程序设计之对象生成方法详解
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2024-04-01 22:06:10
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
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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