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简介
一组实现了同一个策略接口的策略,能够随时指定用哪一种策略实现业务。
策略模式其实跟桥接模式很像,都是通过持有另一个对象,达到组合的成果。
角色
-
Context 上下文
可设置应用的 Strategy
- 形象 Strategy
- 具体 Strategy
类图
如图,Context 应用 setStrategy 办法设置以后应用的策略,在 doSomething 中,调用策略的 execute 办法,实现动静应用策略。
代码
class Context
{
private $strategy;
public function __construct(Strategy $strategy)
{$this->strategy = $strategy;}
public function setStrategy(Strategy $strategy)
{$this->strategy = $strategy;}
public function doSomeBusinessLogic(): void
{echo "Context: Sorting data using the strategy (not sure how it'll do it)\n";
$result = $this->strategy->doAlgorithm(["a", "b", "c", "d", "e"]);
echo implode(",", $result) . "\n";
}
}
interface Strategy
{public function doAlgorithm(array $data): array;
}
class ConcreteStrategyA implements Strategy
{public function doAlgorithm(array $data): array
{sort($data);
return $data;
}
}
class ConcreteStrategyB implements Strategy
{public function doAlgorithm(array $data): array
{rsort($data);
return $data;
}
}
$context = new Context(new ConcreteStrategyA());
echo "Client: Strategy is set to normal sorting.\n";
$context->doSomeBusinessLogic();
echo "Client: Strategy is set to reverse sorting.\n";
$context->setStrategy(new ConcreteStrategyB());
$context->doSomeBusinessLogic();
output:
Client: Strategy is set to normal sorting.
Context: Sorting data using the strategy (not sure how it'll do it)
a,b,c,d,e
Client: Strategy is set to reverse sorting.
Context: Sorting data using the strategy (not sure how it'll do it)
e,d,c,b,a
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