PHP設計模式學習筆記： 命令模式（Command）

// 書本信息操縱類，包括書本的所有操作命令的方法
class BookCommandee {
    private $author;
    private $title;
    function __construct($title_in, $author_in) {
        $this->setAuthor($author_in);
        $this->setTitle($title_in);
    }
    function getAuthor() {
        return $this->author;
    }
    function setAuthor($author_in) {
        $this->author = $author_in;
    }
    function getTitle() {
        return $this->title;
    }
    function setTitle($title_in) {
        $this->title = $title_in;
    }
    function setStarsOn() {
        $this->setAuthor(str_replace(' ','',$this->getAuthor()));
        $this->setTitle(str_replace(' ','',$this->getTitle()));
    }
    function setStarsOff() {
        $this->setAuthor(str_replace('',' ',$this->getAuthor()));
        $this->setTitle(str_replace('',' ',$this->getTitle()));
    }
    function getAuthorAndTitle() {
        return $this->getTitle().' by '.$this->getAuthor();
    }
}

// 抽象類，規定必須有書本操縱類屬性和exexute()方法
abstract class BookCommand {
    protected $bookCommandee;
    function __construct($bookCommandee_in) {
        $this->bookCommandee = $bookCommandee_in;
    }
    abstract function execute();
}
// 繼承自BookCommand抽象類的專門加星標的類
class BookStarsOnCommand extends BookCommand {
    function execute() {
        $this->bookCommandee->setStarsOn();
    }
}
// 繼承自BookCommand抽象類的專門去星標的類
class BookStarsOffCommand extends BookCommand {
    function execute() {
        $this->bookCommandee->setStarsOff();
    }
}
writeln('開始測試命令模式');
  writeln('');
// 創建一個書本操縱類
  $book = new BookCommandee('Design Patterns', 'Gamma, Helm, Johnson, and Vlissides');
// 可以用這個類得到它的書名等屬性
  writeln('創建book之后: ');
  writeln($book->getAuthorAndTitle());
  writeln('');
// 創建一個專門加星標的類
  // 調用它的execute()方法，給書本加星標
  $starsOn = new BookStarsOnCommand($book);
  callCommand($starsOn);
  writeln('book加星標之后: ');
  writeln($book->getAuthorAndTitle());
  writeln('');
// 創建一個專門去星標的類
  // 調用它的execute()方法，給書本去星標
  $starsOff = new BookStarsOffCommand($book);
  callCommand($starsOff);
  writeln('book去星標之后: ');
  writeln($book->getAuthorAndTitle());
  writeln('');
writeln('結束測試命令模式');
function callCommand(BookCommand $bookCommand_in) {
    $bookCommand_in->execute();
  }
function writeln($line_in) {
    echo $line_in.PHP_EOL;
  }
// 我想這個精髓就是，把針對某個類的操作命令，全部放在一個專門的類里面去，調用這個專門的命令類的執行（execute()）方法，
// 就給需要操作的類執行了相應的命令</pre>結果： 
開始測試命令模式

創建book之后: 
Design Patterns by Gamma, Helm, Johnson, and Vlissides
book加星標之后: 
DesignPatterns by Gamma,Helm,Johnson,and*Vlissides
book去星標之后: 
Design Patterns by Gamma, Helm, Johnson, and Vlissides
結束測試命令模式</pre> 
原文地址：http://sourcemaking.com/design_patterns/command