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并肩工作。
一個軍隊的案例，
<?phpabstract 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
<?phpabstract 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
<?phpabstract 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。
<?phpabstract 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用于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 classesclass 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 ( ) ))16Army Object( [units:Army:private] => Array ( [1] => Tank Object ( ) [2] => Tank Object ( ) ))8
添加異常處理
<?phpabstract 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)：
<?phpclass 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( $sub_army );// all the calculations handled behind the scenesprint "attacking with strength: {$main_army->bombardStrength()}/n";?>output:
attacking with strength: 60
更牛逼的組合處理，
<?phpabstract 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() ) ) { // 軍隊合并處理 $comp->addUnit( $newUnit ); } else { // 士兵合并處理 $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
<?phpabstract class Tile { // 磚瓦 abstract function getWealthFactor(); // 獲取財富}class Plains extends Tile { // 平原 private $wealthfactor = 2; function getWealthFactor() { return $this->wealthfactor; }}class DiamondPlains extends Plains { // 鉆石地段 function getWealthFactor() { return parent::getWealthFactor() + 2; }}class PollutedPlains extends Plains { // 污染地段 function getWealthFactor() { return parent::getWealthFactor() - 4; }}$tile = new PollutedPlains();print $tile->getWealthFactor();?> output:
-2
點評：不具有靈活性，我們不能同時獲得鉆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：
<?phpabstract 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 { // 鉆石裝飾 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鉆石被污染的對象。
一個更逼真的例子
<?phpclass 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 requestStructureRequest: structuring requestLogRequest: logging requestMainProcess: doing something useful with requestAuthenticateRequest Object( [processrequest:protected] => StructureRequest Object ( [processrequest:protected] => LogRequest Object ( [processrequest:protected] => MainProcess Object ( ) ) ))
點評：這里有一種遞歸的感覺，一層調用一層。模式是牛人總結出來用于靈活的解決一些現實問題的。牛！給開發多一點思路。
希望本文所述對大家PHP程序設計有所幫助。
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