php常用几种设计模式的应用场景
1.单例设计模式
<?PHP /** * Singleton of Database */ class Database { // We need a static private variable to store a Database instance. privatestatic $instance; // Mark as private to prevent it from being instanced. private function__construct() { // Do nothing. } private function__clone() { // Do nothing. } public static function getInstance() { if (!(self::$instance instanceof self)) { self::$instance = new self(); } return self::$instance; } } $a =Database::getInstance(); $b =Database::getInstance(); // true var_dump($a === $b);
2.工厂设计模式
<?Php interface InterfaceShape { function getArea(); function getCircumference(); } /** * 矩形 */ class Rectangle implements InterfaceShape { private $width; private $height; public function __construct($width, $height) { $this->width = $width; $this->height = $height; } public function getArea() { return $this->width* $this->height; } public function getCircumference() { return 2 * $this->width + 2 * $this->height; } } /** * 圆形 */ class Circle implements InterfaceShape { private $radius; function __construct($radius) { $this->radius = $radius; } public function getArea() { return M_PI * pow($this->radius, 2); } public function getCircumference() { return 2 * M_PI * $this->radius; } } /** * 形状工厂类 */ class FactoryShape { public static function create() { switch (func_num_args()) { case1: return newCircle(func_get_arg(0)); case2: return newRectangle(func_get_arg(0), func_get_arg(1)); default: # code... break; } } } $rect =FactoryShape::create(5, 5); // object(Rectangle)#1 (2) { ["width":"Rectangle":private]=> int(5) ["height":"Rectangle":private]=> int(5) } var_dump($rect); echo "<br>"; // object(Circle)#2 (1) { ["radius":"Circle":private]=> int(4) } $circle =FactoryShape::create(4); var_dump($circle);
3.观察者设计模式
<?php /* 观察者接口 */ interface InterfaceObserver { function onListen($sender, $args); function getObserverName(); } // 可被观察者接口 interface InterfaceObservable { function addObserver($observer); function removeObserver($observer_name); } // 观察者抽象类 abstract class Observer implements InterfaceObserver { protected $observer_name; function getObserverName() { return $this->observer_name; } function onListen($sender, $args) { } } // 可被观察类 abstract class Observable implements InterfaceObservable { protected $observers = array(); public function addObserver($observer) { if ($observer instanceof InterfaceObserver) { $this->observers[] = $observer; } } public function removeObserver($observer_name) { foreach ($this->observersas $index => $observer) { if ($observer->getObserverName() === $observer_name) { array_splice($this->observers, $index, 1); return; } } } } // 模拟一个可以被观察的类 class A extends Observable { public function addListener($listener) { foreach ($this->observers as $observer) { $observer->onListen($this, $listener); } } } // 模拟一个观察者类 class B extends Observer { protected $observer_name = 'B'; public function onListen($sender, $args) { var_dump($sender); echo "<br>"; var_dump($args); echo "<br>"; } } // 模拟另外一个观察者类 class C extends Observer { protected $observer_name = 'C'; public function onListen($sender, $args) { var_dump($sender); echo "<br>"; var_dump($args); echo "<br>"; } } $a = new A(); // 注入观察者 $a->addObserver(new B()); $a->addObserver(new C()); // 可以看到观察到的信息 $a->addListener('D'); // 移除观察者 $a->removeObserver('B'); // 打印的信息： // object(A)#1 (1) { ["observers":protected]=> array(2) { [0]=> object(B)#2 (1) { ["observer_name":protected]=> string(1) "B" } [1]=> object(C)#3 (1) { ["observer_name":protected]=> string(1) "C" } } } // string(1) "D" // object(A)#1 (1) { ["observers":protected]=> array(2) { [0]=> object(B)#2 (1) { ["observer_name":protected]=> string(1) "B" } [1]=> object(C)#3 (1) { ["observer_name":protected]=> string(1) "C" } } } // string(1) "D"
4.适配器模式
//老的代码
class User {
private $name;
function __construct($name) {
$this->name = $name;
}
public function getName() {
return $this->name;
}
}
//新代码，开放平台标准接口
interface UserInterface {
function getUserName();
}
class UserInfo implements UserInterface {
protected $user;
function __construct($user) {
$this->user = $user;
}
public function getUserName() {
return $this->user->getName();
}
}
$olduser = new User('张三');
echo $olduser->getName()."n";
$newuser = new UserInfo($olduser);
echo $newuser->getUserName()."n";5.策略模式
<?php
namespace IMooc;
class MaleUserStrategy implements UserStrategy {
function showAd()
{
echo "IPhone6";
}
function showCategory()
{
echo "电子产品";
}
}<?php
namespace IMooc;
class FemaleUserStrategy implements UserStrategy {
function showAd()
{
echo "2014新款女装";
}
function showCategory()
{
echo "女装";
}
}<?php
namespace IMooc;
interface UserStrategy {
function showAd();
function showCategory();
}<?php
interface FlyBehavior{
public function fly();
}
class FlyWithWings implements FlyBehavior{
public function fly(){
echo "Fly With Wings \n";
}
}
class FlyWithNo implements FlyBehavior{
public function fly(){
echo "Fly With No Wings \n";
}
}
class Duck{
private $_flyBehavior;
public function performFly(){
$this->_flyBehavior->fly();
}
public function setFlyBehavior(FlyBehavior $behavior){
$this->_flyBehavior = $behavior;
}
}
class RubberDuck extends Duck{
}
// Test Case
$duck = new RubberDuck();
/* 想让鸭子用翅膀飞行 */
$duck->setFlyBehavior(new FlyWithWings());
$duck->performFly();
/* 想让鸭子不用翅膀飞行 */
$duck->setFlyBehavior(new FlyWithNo());
$duck->performFly();6.装饰器模式
<?php
namespace IMooc;
interface DrawDecorator
{
function beforeDraw();
function afterDraw();
}<?php
namespace IMooc;
class Canvas
{
public $data;
protected $decorators = array();
//Decorator
function init($width = 20, $height = 10)
{
$data = array();
for($i = 0; $i < $height; $i++)
{
for($j = 0; $j < $width; $j++)
{
$data[$i][$j] = '*';
}
}
$this->data = $data;
}
function addDecorator(DrawDecorator $decorator)
{
$this->decorators[] = $decorator;
}
function beforeDraw()
{
foreach($this->decorators as $decorator)
{
$decorator->beforeDraw();
}
}
function afterDraw()
{
$decorators = array_reverse($this->decorators);
foreach($decorators as $decorator)
{
$decorator->afterDraw();
}
}
function draw()
{
$this->beforeDraw();
foreach($this->data as $line)
{
foreach($line as $char)
{
echo $char;
}
echo "<br />\n";
}
$this->afterDraw();
}
function rect($a1, $a2, $b1, $b2)
{
foreach($this->data as $k1 => $line)
{
if ($k1 < $a1 or $k1 > $a2) continue;
foreach($line as $k2 => $char)
{
if ($k2 < $b1 or $k2 > $b2) continue;
$this->data[$k1][$k2] = ' ';
}
}
}
}<?php
namespace IMooc;
class ColorDrawDecorator implements DrawDecorator
{
protected $color;
function __construct($color = 'red')
{
$this->color = $color;
}
function beforeDraw()
{
echo "<div style='color: {$this->color};'>";
}
function afterDraw()
{
echo "</div>";
}
}<?php
define('BASEDIR', __DIR__);
include BASEDIR.'/IMooc/Loader.php';
spl_autoload_register('\\IMooc\\Loader::autoload');
$canvas = new IMooc\Canvas();
$canvas->init();
$canvas->addDecorator(new \IMooc\ColorDrawDecorator('green'));
$canvas->rect(3,6,4,12);
$canvas->draw();原文链接：https://blog.csdn.net/z15818264727/article/details/52354263
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