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 程式師世界 >> 編程語言 >> 網頁編程 >> PHP編程 >> PHP綜合 >> PHP面向對象程序設計組合模式與裝飾模式詳解

PHP面向對象程序設計組合模式與裝飾模式詳解

編輯:PHP綜合

本文實例講述了PHP面向對象程序設計組合模式與裝飾模式。分享給大家供大家參考,具體如下:

組合模式

定義:組合模式定義了一個單根繼承體系,使具有截然不同職責的集合可以並肩工作。

一個軍隊的案例,

<?php
abstract class Unit { // 個體
  abstract function bombardStrength();
}
class Archer extends Unit { // 弓箭手
  function bombardStrength() {
    return 4;
  }
}
class LaserCannonUnit extends Unit { // 火炮手
  function bombardStrength() {
    return 44;
  }
}
?>

軍隊整合成員,輸出火力

<?php
abstract class Unit {
  abstract function bombardStrength();
}
class Archer extends Unit {
  function bombardStrength() {
    return 4;
  }
}
class LaserCannonUnit extends Unit {
  function bombardStrength() {
    return 44;
  }
}
class Army { // 軍隊
  private $units = array(); // 定義私有屬性 個體集
  function addUnit( Unit $unit ) { // 添加成員
    array_push( $this->units, $unit );
  }
  function bombardStrength() { // 火力
    $ret = 0;
    foreach( $this->units as $unit ) {
      $ret += $unit->bombardStrength();
    }
    return $ret;
  }
}
$unit1 = new Archer();
$unit2 = new LaserCannonUnit();
$army = new Army();
$army->addUnit( $unit1 );
$army->addUnit( $unit2 );
print $army->bombardStrength(); // 輸出火力
?>

output:
48
軍隊進一步整合其他軍隊

<?php
abstract class Unit {
  abstract function bombardStrength();
}
class Archer extends Unit {
  function bombardStrength() {
    return 4;
  }
}
class LaserCannonUnit extends Unit {
  function bombardStrength() {
    return 44;
  }
}
class Army {
  private $units = array();
  private $armies= array();
  function addUnit( Unit $unit ) {
    array_push( $this->units, $unit );
  }
  function addArmy( Army $army ) {
    array_push( $this->armies, $army );
  }
  function bombardStrength() {
    $ret = 0;
    foreach( $this->units as $unit ) {
      $ret += $unit->bombardStrength();
    }
    foreach( $this->armies as $army ) {
      $ret += $army->bombardStrength();
    }
    return $ret;
  }
}
$unit1 = new Archer();
$unit2 = new LaserCannonUnit();
$army = new Army();
$army->addUnit( $unit1 );
$army->addUnit( $unit2 );
print $army->bombardStrength();
print "\n";
$army2 = clone $army; // 克隆軍隊
$army->addArmy( $army2 );
print $army->bombardStrength();
print "\n";
?>

output:
48
96

更好的方式,支持新增,移除等等其他功能。

<?php
abstract class Unit {
  abstract function addUnit( Unit $unit );
  abstract function removeUnit( Unit $unit );
  abstract function bombardStrength();
}
class Army extends Unit { // 軍隊
  private $units = array();
  function addUnit( Unit $unit ) {
    if ( in_array( $unit, $this->units, true ) ) { // $this用於調用正常的屬性或方法,self調用靜態的方法,屬性或者常量
      return;
    }
    $this->units[] = $unit;
  }
  function removeUnit( Unit $unit ) {
    // >= php 5.3
    $this->units = array_udiff( $this->units, array( $unit ),
            function( $a, $b ) { return ($a === $b)?0:1; } );
    // < php 5.3
    // $this->units = array_udiff( $this->units, array( $unit ),
    //        create_function( '$a,$b', 'return ($a === $b)?0:1;' ) );
    // 對象數組,create_function,創建函數
  }
  function bombardStrength() {
    $ret = 0;
    foreach( $this->units as $unit ) {
      $ret += $unit->bombardStrength();
    }
    return $ret;
  }
}
// quick example classes
class Tank extends Unit { // 坦克
  function addUnit( Unit $unit ) {}
  function removeUnit( Unit $unit ) {}
  function bombardStrength() {
    return 4;
  }
}
class Soldier extends Unit { // 士兵
  function addUnit( Unit $unit ) {}
  function removeUnit( Unit $unit ) {}
  function bombardStrength() {
    return 8;
  }
}
$tank = new Tank();
$tank2 = new Tank();
$soldier = new Soldier();
$army = new Army();
$army->addUnit( $soldier );
$army->addUnit( $tank );
$army->addUnit( $tank2 );
print_r( $army );
print $army->bombardStrength()."\n";
$army->removeUnit( $soldier );
print_r( $army );
print $army->bombardStrength()."\n";
?>

output:

Army Object
(
  [units:Army:private] => Array
    (
      [0] => Soldier Object
        (
        )
      [1] => Tank Object
        (
        )
      [2] => Tank Object
        (
        )
    )
)
16
Army Object
(
  [units:Army:private] => Array
    (
      [1] => Tank Object
        (
        )
      [2] => Tank Object
        (
        )
    )
)
8

添加異常處理

<?php
abstract class Unit {
  abstract function addUnit( Unit $unit );
  abstract function removeUnit( Unit $unit );
  abstract function bombardStrength();
}
class Army extends Unit {
  private $units = array();
  function addUnit( Unit $unit ) {
    if ( in_array( $unit, $this->units, true ) ) {
      return;
    }
    $this->units[] = $unit;
  }
  function removeUnit( Unit $unit ) {
    // >= php 5.3
    //$this->units = array_udiff( $this->units, array( $unit ),
    //        function( $a, $b ) { return ($a === $b)?0:1; } );
    // < php 5.3
    $this->units = array_udiff( $this->units, array( $unit ),
            create_function( '$a,$b', 'return ($a === $b)?0:1;' ) );
  }
  function bombardStrength() {
    $ret = 0;
    foreach( $this->units as $unit ) {
      $ret += $unit->bombardStrength();
    }
    return $ret;
  }
}
class UnitException extends Exception {}
class Archer extends Unit {
  function addUnit( Unit $unit ) {
    throw new UnitException( get_class($this)." is a leaf" );
  }
  function removeUnit( Unit $unit ) {
    throw new UnitException( get_class($this)." is a leaf" );
  }
  function bombardStrength() {
    return 4;
  }
}
$archer = new Archer();
$archer2 = new Archer();
$archer->addUnit( $archer2 );
?>

output:

Fatal error: Uncaught exception 'UnitException' with message 'Archer is a leaf'

點評:組合模式中的一切類都共享同一個父類型,可以輕松地在設計中添加新的組合對象或局部對象,而無需大范圍地修改代碼。

最終的效果,逐步優化(完美):

<?php
class UnitException extends Exception {}
abstract class Unit {
  abstract function bombardStrength();
  function addUnit( Unit $unit ) {
    throw new UnitException( get_class($this)." is a leaf" );
  }
  function removeUnit( Unit $unit ) {
    throw new UnitException( get_class($this)." is a leaf" );
  }
}
class Archer extends Unit {
  function bombardStrength() {
    return 4;
  }
}
class LaserCannonUnit extends Unit {
  function bombardStrength() {
    return 44;
  }
}
class Army extends Unit {
  private $units = array();
  function addUnit( Unit $unit ) {
    if ( in_array( $unit, $this->units, true ) ) {
      return;
    }
    $this->units[] = $unit;
  }
  function removeUnit( Unit $unit ) {
    // >= php 5.3
    //$this->units = array_udiff( $this->units, array( $unit ),
    //        function( $a, $b ) { return ($a === $b)?0:1; } );
    // < php 5.3
    $this->units = array_udiff( $this->units, array( $unit ),
            create_function( '$a,$b', 'return ($a === $b)?0:1;' ) );
  }
  function bombardStrength() {
    $ret = 0;
    foreach( $this->units as $unit ) {
      $ret += $unit->bombardStrength();
    }
    return $ret;
  }
}
// create an army
$main_army = new Army();
// add some units
$main_army->addUnit( new Archer() );
$main_army->addUnit( new LaserCannonUnit() );
// create a new army
$sub_army = new Army();
// add some units
$sub_army->addUnit( new Archer() );
$sub_army->addUnit( new Archer() );
$sub_army->addUnit( new Archer() );
// add the second army to the first
$main_army->addUnit( $sub_army );
// all the calculations handled behind the scenes
print "attacking with strength: {$main_army->bombardStrength()}\n";
?>

output:

attacking with strength: 60

更牛逼的組合處理,

<?php
abstract class Unit {
  function getComposite() {
    return null;
  }
  abstract function bombardStrength();
}
abstract class CompositeUnit extends Unit { // 抽象類繼承抽象類
  private $units = array();
  function getComposite() {
    return $this;
  }
  protected function units() {
    return $this->units;
  }
  function removeUnit( Unit $unit ) {
    // >= php 5.3
    //$this->units = array_udiff( $this->units, array( $unit ),
    //        function( $a, $b ) { return ($a === $b)?0:1; } );
    // < php 5.3
    $this->units = array_udiff( $this->units, array( $unit ),
            create_function( '$a,$b', 'return ($a === $b)?0:1;' ) );
  }
  function addUnit( Unit $unit ) {
    if ( in_array( $unit, $this->units, true ) ) {
      return;
    }
    $this->units[] = $unit;
  }
}
class Army extends CompositeUnit {
  function bombardStrength() {
    $ret = 0;
    foreach( $this->units as $unit ) {
      $ret += $unit->bombardStrength();
    }
    return $ret;
  }
}
class Archer extends Unit {
  function bombardStrength() {
    return 4;
  }
}
class LaserCannonUnit extends Unit {
  function bombardStrength() {
    return 44;
  }
}
class UnitScript {
  static function joinExisting( Unit $newUnit,
                 Unit $occupyingUnit ) { // 靜態方法,直接通過類名來使用
    $comp;
    if ( ! is_null( $comp = $occupyingUnit->getComposite() ) ) { // 軍隊合並處理
      $comp->addUnit( $newUnit );
    } else { // 士兵合並處理
      $comp = new Army();
      $comp->addUnit( $occupyingUnit );
      $comp->addUnit( $newUnit );
    }
    return $comp;
  }
}
$army1 = new Army();
$army1->addUnit( new Archer() );
$army1->addUnit( new Archer() );
$army2 = new Army();
$army2->addUnit( new Archer() );
$army2->addUnit( new Archer() );
$army2->addUnit( new LaserCannonUnit() );
$composite = UnitScript::joinExisting( $army2, $army1 );
print_r( $composite );
?>

output:

Army Object
(
  [units:CompositeUnit:private] => Array
    (
      [0] => Archer Object
        (
        )
      [1] => Archer Object
        (
        )
      [2] => Army Object
        (
          [units:CompositeUnit:private] => Array
            (
              [0] => Archer Object
                (
                )
              [1] => Archer Object
                (
                )
              [2] => LaserCannonUnit Object
                (
                )
            )
        )
    )
)

點評:Unit 基礎,CompositeUnit復合中實現add與remove。軍隊繼承Composite,射手繼承Archer。這樣射手中就不會有多余的add與remove方法了。

裝飾模式

裝飾模式幫助我們改變具體組件的功能。

看例子

<?php
abstract class Tile { // 磚瓦
  abstract function getWealthFactor(); // 獲取財富
}
class Plains extends Tile { // 平原
  private $wealthfactor = 2;
  function getWealthFactor() {
    return $this->wealthfactor;
  }
}
class DiamondPlains extends Plains { // 鑽石地段
  function getWealthFactor() {
    return parent::getWealthFactor() + 2;
  }
}
class PollutedPlains extends Plains { // 污染地段
  function getWealthFactor() {
    return parent::getWealthFactor() - 4;
  }
}
$tile = new PollutedPlains();
print $tile->getWealthFactor();
?>

output:
-2

點評:不具有靈活性,我們不能同時獲得鑽石與被污染的土地的資金情況。

裝飾模式使用組合和委托而不是只使用繼承來解決功能變化的問題。

看例子:

<?php
abstract class Tile {
  abstract function getWealthFactor();
}
class Plains extends Tile {
  private $wealthfactor = 2;
  function getWealthFactor() {
    return $this->wealthfactor;
  }
}
abstract class TileDecorator extends Tile { // 裝飾
  protected $tile;
  function __construct( Tile $tile ) {
    $this->tile = $tile;
  }
}
class DiamondDecorator extends TileDecorator { // 鑽石裝飾
  function getWealthFactor() {
    return $this->tile->getWealthFactor()+2;
  }
}
class PollutionDecorator extends TileDecorator { // 污染裝飾
  function getWealthFactor() {
    return $this->tile->getWealthFactor()-4;
  }
}
$tile = new Plains();
print $tile->getWealthFactor(); // 2
$tile = new DiamondDecorator( new Plains() );
print $tile->getWealthFactor(); // 4
$tile = new PollutionDecorator(
       new DiamondDecorator( new Plains() ));
print $tile->getWealthFactor(); // 0
?>

output:
2
4
0

點評:這個模型具有擴展性。我們不需要創建DiamondPollutionPlains對象就可以構建一個鑽石被污染的對象。

一個更逼真的例子

<?php
class RequestHelper{} // 請求助手
abstract class ProcessRequest { // 進程請求
  abstract function process( RequestHelper $req );
}
class MainProcess extends ProcessRequest { // 主進程
  function process( RequestHelper $req ) {
    print __CLASS__.": doing something useful with request\n";
  }
}
abstract class DecorateProcess extends ProcessRequest { // 裝飾進程
  protected $processrequest;
  function __construct( ProcessRequest $pr ) { // 引用對象,委托
    $this->processrequest = $pr;
  }
}
class LogRequest extends DecorateProcess { // 日志請求
  function process( RequestHelper $req ) {
    print __CLASS__.": logging request\n"; // 當前類,有點遞歸的感覺
    $this->processrequest->process( $req );
  }
}
class AuthenticateRequest extends DecorateProcess { // 認證請求
  function process( RequestHelper $req ) {
    print __CLASS__.": authenticating request\n";
    $this->processrequest->process( $req );
  }
}
class StructureRequest extends DecorateProcess { // 組織結構請求
  function process( RequestHelper $req ) {
    print __CLASS__.": structuring request\n";
    $this->processrequest->process( $req );
  }
}
$process = new AuthenticateRequest( new StructureRequest(
                  new LogRequest (
                  new MainProcess()
                  ))); // 這樣可以很靈活的組合進程的關系,省去很多重復的繼承
$process->process( new RequestHelper() );
print_r($process);
?>

output:

AuthenticateRequest: authenticating request
StructureRequest: structuring request
LogRequest: logging request
MainProcess: doing something useful with request
AuthenticateRequest Object
(
  [processrequest:protected] => StructureRequest Object
    (
      [processrequest:protected] => LogRequest Object
        (
          [processrequest:protected] => MainProcess Object
            (
            )
        )
    )
)

點評:這裡有一種遞歸的感覺,一層調用一層。模式是牛人總結出來用於靈活的解決一些現實問題的。牛!給開發多一點思路。

更多關於PHP相關內容感興趣的讀者可查看本站專題:《php面向對象程序設計入門教程》、《PHP基本語法入門教程》、《PHP運算與運算符用法總結》、《PHP網絡編程技巧總結》、《PHP數組(Array)操作技巧大全》、《php字符串(string)用法總結》、《php+mysql數據庫操作入門教程》及《php常見數據庫操作技巧匯總》

希望本文所述對大家PHP程序設計有所幫助。

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