委托模式代码,PHP代码库,德仔网

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【PHP】委托模式
作者:PHP设计模式 / 发布于2011/11/29/ 633
<div>?<?php
/**
* 转自 《PHP设计模式》 第七章： 委托模式
* 当一个对象包含复杂单独立的，必须基于判决执行的功能性的若干部分时，最佳的方法是适用基于委托设计模式的对象。 
*
*/</div>
<div>/**
* 示例： Web站点具有创建MP3文件播放列表的功能， 也具有选择以 M3U 或 PLS 格式下载播放列表的功能。
*
* 以下代码示例展示常规与委托两种模式实现
*
*/
//常规实现 
class Playlist {

private $_songs; 

public function __construct() {
$this->_songs = array();
}

public function addSong($location, $title) {
$song = array("location" => $location, "title" => $title);
$this->_songs[] = $song;
}

public function getM3U() {
$m3u = "#EXTM3U\n\n";

foreach ($this->_songs as $song) {
$m3u .= "#EXTINF: -1, {$song['title']}\n";
$m3u .= "{$song['location']}\n";
}

return $m3u;
}

public function getPLS() {
$pls = "[playlist]]\nNumberOfEntries = ". count($this->_songs) . "\n\n";

foreach ($this->_songs as $songCount => $song) {
$counter = $songCount + 1;
$pls .= "File{$counter} = {$song['location']}\n";
$pls .= "Title{$counter} = {$song['title']}\n";
$pls .= "LengthP{$counter} = -1 \n\n";
}

return $pls;
}
}
<div>$playlist = new Playlist();</div>
<div>$playlist->addSong("/home/aaron/music/brr.mp3", "Brr");
$playlist->addSong("/home/aaron/music/goodbye.mp3", "Goodbye");</div>
<div>$externalRetrievedType = "pls";</div>
if ($externalRetrievedType == "pls") {
$playlistContent = $playlist->getPLS();
} else {
$playlistContent = $playlist->getM3U();
}
<div>echo $playlistContent;</div>
<div>//委托模式实现 
class newPlaylist {</div>
<div>private $_songs;
private $_tyepObject;</div>
<div>public function __construct($type) {
$this->_songs = array();
$object = "{$type}Playlist";
$this->_tyepObject = new $object;
}

public function addSong($location, $title) {
$song = array("location" => $location, "title" => $title);
$this->_songs[] = $song;
}

public function getPlaylist() {
$playlist = $this->_tyepObject->getPlaylist($this->_songs);
return $playlist;
}
}
<div>class m3uPlaylist {
public function getPlaylist($songs) {
$m3u = "#EXTM3U\n\n";

foreach ($songs as $song) {
$m3u .= "#EXTINF: -1, {$song['title']}\n";
$m3u .= "{$song['location']}\n";
}

return $m3u;
}
}
<div>class plsPlaylist {
public function getPlaylist($songs) {
$pls = "[playlist]]\nNumberOfEntries = ". count($songs) . "\n\n";

foreach ($songs as $songCount => $song) {
$counter = $songCount + 1;
$pls .= "File{$counter} = {$song['location']}\n";
$pls .= "Title{$counter} = {$song['title']}\n";
$pls .= "LengthP{$counter} = -1 \n\n";
}

return $pls;
}
}
<div>$externalRetrievedType = "pls";
$playlist = new newPlaylist($externalRetrievedType);</div>
<div>$playlist->addSong("/home/aaron/music/brr.mp3", "Brr");
$playlist->addSong("/home/aaron/music/goodbye.mp3", "Goodbye");</div>
<div>$playlistContent = $playlist->getPlaylist();</div>
<div>echo $playlistContent;</div>
<div>/* End of Delegate.class.php */
/* Location the file Design/Delegate.class.php */</div>
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