装饰器模式
允许向一个已有的对象动态添加新的功能,又不改变其结构,使用子类继承的方法去实现添加新功能,会不可避免的出现子类过多,继承链很长额情况.
目录结构
|decorator #项目根目录
|--Think #核心类库
|----Loder.php #自动加载类
|----decorator.php #装饰器接口
|----colorDecorator.php #颜色装饰器
|----sizeDecorator.php #字体大小装饰器
|----echoText.php #被装饰者
|--index.php #单一的入口文件
代码实践
装饰器接口 Think/decorator.php
<?php
/**
* 装饰器接口
* Interface decorator
* @package Think
*/
namespace Think;
interface decorator{
public function beforeDraw();
public function afterDraw();
}
颜色装饰器 Think/colorDecorator.php
<?php
/**
* 颜色装饰器
*/
namespace Think;
class colorDecorator implements decorator{
protected $color;
public function __construct($color) {
$this->color = $color;
}
public function beforeDraw() {
echo "color decorator :{$this->color}\n";
}
public function afterDraw() {
echo "end color decorator\n";
}
}
字体大小装饰器 Think/sizeDecorator.php
<?php
/**
* 字体大小装饰器
*/
namespace Think;
class sizeDecorator implements decorator{
protected $size;
public function __construct($size) {
$this->size = $size;
}
public function beforeDraw() {
echo "size decorator {$this->size}\n";
}
public function afterDraw() {
echo "end size decorator\n";
}
}
被装饰者 Think/echoText.php
<?php
/**
* 被装饰者
*/
namespace Think;
class echoText {
protected $decorator = array(); //存放装饰器
//装饰方法
public function index() {
//调用装饰器前置操作
$this->before();
echo "你好,我是装饰器\n";
//执行装饰器后置操作
$this->after();
}
public function addDecorator(Decorator $decorator) {
$this->decorator[] = $decorator;
}
//执行装饰器前置操作 先进先出
public function before() {
foreach ($this->decorator as $decorator){
$decorator->beforeDraw();
}
}
//执行装饰器后置操作 先进后出
public function after() {
$decorators = array_reverse($this->decorator);
foreach ($decorators as $decorator){
$decorator->afterDraw();
}
}
}
自动加载 Think/Loder.php
<?php
namespace Think;
class Loder{
static function autoload($class){
require BASEDIR . '/' .str_replace('\\','/',$class) . '.php';
}
}
入口文件index.php
<?php
define('BASEDIR',__DIR__);
include BASEDIR . '/Think/Loder.php';
spl_autoload_register('\\Think\\Loder::autoload');
//实例化输出类
$echo = new \Think\echoText();
//增加装饰器
$echo->addDecorator(new \Think\colorDecorator('red'));
//增加装饰器
$echo->addDecorator(new \Think\sizeDecorator('12'));
//装饰方法
$echo->index();
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