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这篇文章将为大家详细讲解有关PHP中组合模式与装饰模式的示例分析,小编觉得挺实用的,因此分享给大家做个参考,希望大家阅读完这篇文章后可以有所收获。
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组合模式
定义:组合模式定义了一个单根继承体系,使具有截然不同职责的集合可以并肩工作。
一个军队的案例,
军队整合成员,输出火力
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(); // 输出火力 ?>
output:
48
军队进一步整合其他军队
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; // 克隆军队 $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。
units, true ) ) { // $this用于调用正常的属性或方法,self调用静态的方法,属性或者常量 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;' ) ); // 对象数组,create_function,创建函数 } 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
添加异常处理
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'
点评:组合模式中的一切类都共享同一个父类型,可以轻松地在设计中添加新的组合对象或局部对象,而无需大范围地修改代码。
最终的效果,逐步优化(完美):
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
更牛逼的组合处理,
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 ) { // 静态方法,直接通过类名来使用 $comp; if ( ! is_null( $comp = $occupyingUnit->getComposite() ) ) { // 军队合并处理 $comp->addUnit( $newUnit ); } else { // 士兵合并处理 $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 ( ) ) ) ) )
点评:Unit 基础,CompositeUnit复合中实现add与remove。军队继承Composite,射手继承Archer。这样射手中就不会有多余的add与remove方法了。
装饰模式
装饰模式帮助我们改变具体组件的功能。
看例子
wealthfactor; } } class DiamondPlains extends Plains { // 钻石地段 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
点评:不具有灵活性,我们不能同时获得钻石与被污染的土地的资金情况。
装饰模式使用组合和委托而不是只使用继承来解决功能变化的问题。
看例子:
wealthfactor; } } abstract class TileDecorator extends Tile { // 装饰 protected $tile; function __construct( Tile $tile ) { $this->tile = $tile; } } class DiamondDecorator extends TileDecorator { // 钻石装饰 function getWealthFactor() { return $this->tile->getWealthFactor()+2; } } class PollutionDecorator extends TileDecorator { // 污染装饰 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
点评:这个模型具有扩展性。我们不需要创建DiamondPollutionPlains对象就可以构建一个钻石被污染的对象。
一个更逼真的例子
processrequest = $pr; } } class LogRequest extends DecorateProcess { // 日志请求 function process( RequestHelper $req ) { print __CLASS__.": logging request\n"; // 当前类,有点递归的感觉 $this->processrequest->process( $req ); } } class AuthenticateRequest extends DecorateProcess { // 认证请求 function process( RequestHelper $req ) { print __CLASS__.": authenticating request\n"; $this->processrequest->process( $req ); } } class StructureRequest extends DecorateProcess { // 组织结构请求 function process( RequestHelper $req ) { print __CLASS__.": structuring request\n"; $this->processrequest->process( $req ); } } $process = new AuthenticateRequest( new StructureRequest( new LogRequest ( new MainProcess() ))); // 这样可以很灵活的组合进程的关系,省去很多重复的继承 $process->process( new RequestHelper() ); print_r($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 ( ) ) ) )
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