php设计模式 装饰器模式 - tianxintian22

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 style="color: #000000;">php
namespace Baobab;
</span><span style="color: #008000;">/*</span><span style="color: #008000;">*
 * 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 style="color: #008000;">*/</span>
<span style="color: #0000ff;">interface</span><span style="color: #000000;"> DrawDecorator{
    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> beforeDraw();
    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> afterDraw();
}</span>

<span>Canvas</span>.php

<span style="color: #000000;">php
namespace Baobab;
<br><span style="color: #008000;">/**</span><br><span style="color: #008000;">*Canvas类，绘制图形</span><br><span style="color: #008000;">**/</span><br>
</span><span style="color: #0000ff;">class</span><span style="color: #000000;"> Canvas
{
    </span><span style="color: #0000ff;">public</span> <span style="color: #800080;">$data</span><span style="color: #000000;">;
    </span><strong><span style="color: #0000ff;">protected</span> <span style="color: #800080;">$decorators</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">();

    </span></strong><span style="color: #008000;">//</span><span style="color: #008000;">Decorator</span>
    <span style="color: #0000ff;">function</span> init(<span style="color: #800080;">$width</span> = 20, <span style="color: #800080;">$height</span> = 10<span style="color: #000000;">)
    {
        </span><span style="color: #800080;">$data</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">();
        </span><span style="color: #0000ff;">for</span>(<span style="color: #800080;">$i</span> = 0; <span style="color: #800080;">$i</span> $height; <span style="color: #800080;">$i</span>++<span style="color: #000000;">)
        {
            </span><span style="color: #0000ff;">for</span>(<span style="color: #800080;">$j</span> = 0; <span style="color: #800080;">$j</span> $width; <span style="color: #800080;">$j</span>++<span style="color: #000000;">)
            {
                </span><span style="color: #800080;">$data</span>[<span style="color: #800080;">$i</span>][<span style="color: #800080;">$j</span>] = '*'<span style="color: #000000;">;
            }
        }
        </span><span style="color: #800080;">$this</span>->data = <span style="color: #800080;">$data</span><span style="color: #000000;">;
    }

    </span><strong><span style="color: #0000ff;">function</span> addDecorator(DrawDecorator <span style="color: #800080;">$decorator</span><span style="color: #000000;">){
        </span><span style="color: #800080;">$this</span>->decorators[] = <span style="color: #800080;">$decorator</span><span style="color: #000000;">;
    }

    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> beforeDraw(){
        </span><span style="color: #0000ff;">foreach</span>(<span style="color: #800080;">$this</span>->decorators <span style="color: #0000ff;">as</span> <span style="color: #800080;">$decorator</span><span style="color: #000000;">){
            </span><span style="color: #800080;">$decorator</span>-><span style="color: #000000;">beforeDraw();
        }
    }

    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> afterDraw(){
        </span><span style="color: #800080;">$decorators</span> = <span style="color: #008080;">array_reverse</span>(<span style="color: #800080;">$this</span>-><span style="color: #000000;">decorators);
        </span><span style="color: #0000ff;">foreach</span>(<span style="color: #800080;">$decorators</span> <span style="color: #0000ff;">as</span> <span style="color: #800080;">$decorator</span><span style="color: #000000;">){
            </span><span style="color: #800080;">$decorator</span>-><span style="color: #000000;">afterDraw();
        }
    }

    </span></strong><span style="color: #0000ff;">function</span><span style="color: #000000;"> draw()
    {
        </span><strong><span style="color: #800080;">$this</span>-><span style="color: #000000;">beforeDraw();
        </span></strong><span style="color: #0000ff;">foreach</span>(<span style="color: #800080;">$this</span>->data <span style="color: #0000ff;">as</span> <span style="color: #800080;">$line</span><span style="color: #000000;">)
        {
            </span><span style="color: #0000ff;">foreach</span>(<span style="color: #800080;">$line</span> <span style="color: #0000ff;">as</span> <span style="color: #800080;">$char</span><span style="color: #000000;">)
            {
                </span><span style="color: #0000ff;">echo</span> <span style="color: #800080;">$char</span><span style="color: #000000;">;
            }
            </span><span style="color: #0000ff;">echo</span> "<br>\n"<span style="color: #000000;">;
        }
        </span><strong><span style="color: #800080;">$this</span>-></strong><span style="color: #000000;"><strong>afterDraw();</strong>
    }

    </span><span style="color: #0000ff;">function</span> rect(<span style="color: #800080;">$a1</span>, <span style="color: #800080;">$a2</span>, <span style="color: #800080;">$b1</span>, <span style="color: #800080;">$b2</span><span style="color: #000000;">)
    {
        </span><span style="color: #0000ff;">foreach</span>(<span style="color: #800080;">$this</span>->data <span style="color: #0000ff;">as</span> <span style="color: #800080;">$k1</span> => <span style="color: #800080;">$line</span><span style="color: #000000;">)
        {
            </span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$k1</span> $a1 or <span style="color: #800080;">$k1</span> > <span style="color: #800080;">$a2</span>) <span style="color: #0000ff;">continue</span><span style="color: #000000;">;
            </span><span style="color: #0000ff;">foreach</span>(<span style="color: #800080;">$line</span> <span style="color: #0000ff;">as</span> <span style="color: #800080;">$k2</span> => <span style="color: #800080;">$char</span><span style="color: #000000;">)
            {
                </span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$k2</span> $b1 or <span style="color: #800080;">$k2</span> > <span style="color: #800080;">$b2</span>) <span style="color: #0000ff;">continue</span><span style="color: #000000;">;
                </span><span style="color: #800080;">$this</span>->data[<span style="color: #800080;">$k1</span>][<span style="color: #800080;">$k2</span>] = ' '<span style="color: #000000;">;
            }
        }
    }
}</span>

<span>ColorDrawDecorator</span>.php

<span style="color: #000000;">php
namespace Baobab;
<span style="color: #008000;">/**</span><br><span style="color: #008000;">*修改图形颜色的装饰器</span><br><span style="color: #008000;">*/
</span></span><span style="color: #0000ff;">class</span> ColorDrawDecorator <span style="color: #0000ff;">implements</span><span style="color: #000000;"> \Baobab\DrawDecorator{
    </span><span style="color: #0000ff;">protected</span> <span style="color: #800080;">$color</span><span style="color: #000000;">;
    </span><span style="color: #0000ff;">function</span> __construct(<span style="color: #800080;">$color</span> = 'black'<span style="color: #000000;">){
        </span><span style="color: #800080;">$this</span>->color = <span style="color: #800080;">$color</span><span style="color: #000000;">;
    }

    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> beforeDraw(){
        </span><span style="color: #0000ff;">echo</span> "<div style='color: {<span style="color: #800080;">$this</span>->color};'>"<span style="color: #000000;">;
    }<br>
    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> afterDraw(){
        </span><span style="color: #0000ff;">echo</span> "</div>"<span style="color: #000000;">;
    }
}</span>

<span>SizeDrawDecorator</span>.php

<span style="color: #000000;">php
namespace Baobab;
<span style="color: #000000;"><span style="color: #008000;">/**<br><span style="color: #008000;">*修改图形大小的装饰器<br><span style="color: #008000;">*/
</span></span></span></span>
</span><span style="color: #0000ff;">class</span> SizeDrawDecorator <span style="color: #0000ff;">implements</span><span style="color: #000000;"> \Baobab\DrawDecorator{
    </span><span style="color: #0000ff;">protected</span> <span style="color: #800080;">$size</span><span style="color: #000000;">;
    </span><span style="color: #0000ff;">function</span> __construct(<span style="color: #800080;">$size</span> = '12px'<span style="color: #000000;">){
        </span><span style="color: #800080;">$this</span>->size = <span style="color: #800080;">$size</span><span style="color: #000000;">;
    }

    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> beforeDraw()
    {
        </span><span style="color: #0000ff;">echo</span> "<div style='font-size: {<span style="color: #800080;">$this</span>->size};'>"<span style="color: #000000;">;
    }<br>
    </span><span style="color: #0000ff;">function</span><span style="color: #000000;"> afterDraw()
    {
        </span><span style="color: #0000ff;">echo</span> "</div>"<span style="color: #000000;">;
    }
}</span>

index.php

<span style="color: #800080;">$canvas</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> Baobab\Canvas();
</span><span style="color: #800080;">$canvas</span>-><span style="color: #000000;">init();
</span><span style="color: #800080;">$canvas</span>->rect(3, 6,4,12<span style="color: #000000;">);

</span><span style="color: #800080;">$canvas</span>->addDecorator(<span style="color: #0000ff;">new</span> \Baobab\ColorDrawDecorator('blue'<span style="color: #000000;">));
</span><span style="color: #800080;">$canvas</span>->addDecorator(<span style="color: #0000ff;">new</span> \Baobab\SizeDrawDecorator('10px'<span style="color: #000000;">));<br>......<br>//可添加其他更多装饰器<br>
</span><span style="color: #800080;">$canvas</span>->draw();