php設計模式 裝飾器模式，php設計模式_PHP教程

php設計模式 裝飾器模式，php設計模式

裝飾器模式，可以動態地添加修改類的功能。

一個類提供了一項功能，如果要修改並添加額外的功能，傳統的編程模式需要寫一個子類繼承它，並重新實作類別的方法。使用裝飾器模式，僅需要在運行時添加一個裝飾器對象即可實現，可以實現最大的靈活性。

DrawDecorator.php

phpnamespace Baobab;/** * Interface DrawDecorator * @package Baobab * 裝飾器介面，定義兩個方法,渲染畫布之前和之後可添加額外的能力 */interface DrawDecorator{    function beforeDraw();    function afterDraw();}

Canvas.php

phpnamespace Baobab;
/**
*Canvas類，繪製圖形
**/
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 "
\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] = ' ';            }        }    }}

ColorDrawDecorator.php

phpnamespace Baobab;/**
*修改圖形顏色的裝飾器
*/class ColorDrawDecorator implements \Baobab\DrawDecorator{    protected $color;    function __construct($color = 'black'){        $this->color = $color;    }    function beforeDraw(){        echo "$this->color};'>";    }
    function afterDraw(){        echo "";    }}

SizeDrawDecorator.php

phpnamespace Baobab;/**
*修改圖形大小的裝飾器
*/class SizeDrawDecorator implements \Baobab\DrawDecorator{    protected $size;    function __construct($size = '12px'){        $this->size = $size;    }    function beforeDraw()    {        echo "$this->size};'>";    }
    function afterDraw()    {        echo "";    }}

index.php

$canvas = new Baobab\Canvas();$canvas->init();$canvas->rect(3, 6,4,12);$canvas->addDecorator(new \Baobab\ColorDrawDecorator('blue'));$canvas->addDecorator(new \Baobab\SizeDrawDecorator('10px'));
......
//可添加其他更多裝飾器
$canvas->draw();

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