php设计模式 装饰器模式，php设计模式
装饰器模式，可以动态地添加修改类的功能。
一个类提供了一项功能，如果要修改并添加额外的功能，传统的编程模式需要写一个子类继承它，并重新实现类的方法。使用装饰器模式，仅需要在运行时添加一个装饰器对象即可实现，可以实现最大的灵活性。
<span>DrawDecorator</span>.php
<?<span>php
namespace Baobab;
</span><span>/*</span><span>*
* Interface DrawDecorator
* @package Baobab
* 装饰器接口，定义两个方法,渲染画布之前和之后可添加额外的能力
</span><span>*/</span>
<span>interface</span><span> DrawDecorator{
</span><span>function</span><span> beforeDraw();
</span><span>function</span><span> afterDraw();
}</span><span>Canvas</span>.php
<?<span>php
namespace Baobab;
<br><span>/**</span><br><span>*Canvas类，绘制图形</span><br><span>**/</span><br>
</span><span>class</span><span> Canvas
{
</span><span>public</span> <span>$data</span><span>;
</span><strong><span>protected</span> <span>$decorators</span> = <span>array</span><span>();
</span></strong><span>//</span><span>Decorator</span>
<span>function</span> init(<span>$width</span> = 20, <span>$height</span> = 10<span>)
{
</span><span>$data</span> = <span>array</span><span>();
</span><span>for</span>(<span>$i</span> = 0; <span>$i</span> < <span>$height</span>; <span>$i</span>++<span>)
{
</span><span>for</span>(<span>$j</span> = 0; <span>$j</span> < <span>$width</span>; <span>$j</span>++<span>)
{
</span><span>$data</span>[<span>$i</span>][<span>$j</span>] = '*'<span>;
}
}
</span><span>$this</span>->data = <span>$data</span><span>;
}
</span><strong><span>function</span> addDecorator(DrawDecorator <span>$decorator</span><span>){
</span><span>$this</span>->decorators[] = <span>$decorator</span><span>;
}
</span><span>function</span><span> beforeDraw(){
</span><span>foreach</span>(<span>$this</span>->decorators <span>as</span> <span>$decorator</span><span>){
</span><span>$decorator</span>-><span>beforeDraw();
}
}
</span><span>function</span><span> afterDraw(){
</span><span>$decorators</span> = <span>array_reverse</span>(<span>$this</span>-><span>decorators);
</span><span>foreach</span>(<span>$decorators</span> <span>as</span> <span>$decorator</span><span>){
</span><span>$decorator</span>-><span>afterDraw();
}
}
</span></strong><span>function</span><span> draw()
{
</span><strong><span>$this</span>-><span>beforeDraw();
</span></strong><span>foreach</span>(<span>$this</span>->data <span>as</span> <span>$line</span><span>)
{
</span><span>foreach</span>(<span>$line</span> <span>as</span> <span>$char</span><span>)
{
</span><span>echo</span> <span>$char</span><span>;
}
</span><span>echo</span> "<br />\n"<span>;
}
</span><strong><span>$this</span>-></strong><span><strong>afterDraw();</strong>
}
</span><span>function</span> rect(<span>$a1</span>, <span>$a2</span>, <span>$b1</span>, <span>$b2</span><span>)
{
</span><span>foreach</span>(<span>$this</span>->data <span>as</span> <span>$k1</span> => <span>$line</span><span>)
{
</span><span>if</span> (<span>$k1</span> < <span>$a1</span> or <span>$k1</span> > <span>$a2</span>) <span>continue</span><span>;
</span><span>foreach</span>(<span>$line</span> <span>as</span> <span>$k2</span> => <span>$char</span><span>)
{
</span><span>if</span> (<span>$k2</span> < <span>$b1</span> or <span>$k2</span> > <span>$b2</span>) <span>continue</span><span>;
</span><span>$this</span>->data[<span>$k1</span>][<span>$k2</span>] = ' '<span>;
}
}
}
}</span><span>ColorDrawDecorator</span>.php
<?<span>php
namespace Baobab;
<span>/**</span><br><span>*修改图形颜色的装饰器</span><br><span>*/
</span></span><span>class</span> ColorDrawDecorator <span>implements</span><span> \Baobab\DrawDecorator{
</span><span>protected</span> <span>$color</span><span>;
</span><span>function</span> __construct(<span>$color</span> = 'black'<span>){
</span><span>$this</span>->color = <span>$color</span><span>;
}
</span><span>function</span><span> beforeDraw(){
</span><span>echo</span> "<div style='color: {<span>$this</span>->color};'>"<span>;
}<br>
</span><span>function</span><span> afterDraw(){
</span><span>echo</span> "</div>"<span>;
}
}</span><span>SizeDrawDecorator</span>.php
<?<span>php
namespace Baobab;
<span><span>/**<br><span>*修改图形大小的装饰器<br><span>*/
</span></span></span></span>
</span><span>class</span> SizeDrawDecorator <span>implements</span><span> \Baobab\DrawDecorator{
</span><span>protected</span> <span>$size</span><span>;
</span><span>function</span> __construct(<span>$size</span> = '12px'<span>){
</span><span>$this</span>->size = <span>$size</span><span>;
}
</span><span>function</span><span> beforeDraw()
{
</span><span>echo</span> "<div style='font-size: {<span>$this</span>->size};'>"<span>;
}<br>
</span><span>function</span><span> afterDraw()
{
</span><span>echo</span> "</div>"<span>;
}
}</span>index.php
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<span>$canvas</span> = <span>new</span><span> Baobab\Canvas();
</span><span>$canvas</span>-><span>init();
</span><span>$canvas</span>->rect(3, 6,4,12<span>);
</span><span>$canvas</span>->addDecorator(<span>new</span> \Baobab\ColorDrawDecorator('blue'<span>));
</span><span>$canvas</span>->addDecorator(<span>new</span> \Baobab\SizeDrawDecorator('10px'<span>));<br>......<br>//可添加其他更多装饰器<br>
</span><span>$canvas</span>->draw();
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