<?php
/**
 * 抽象策略角色，以接口实现
 */
interface Strategy {
 
  /**
   * 算法接口
   */
  public function algorithmInterface();
}
 
/**
 * 具体策略角色A
 */
class ConcreteStrategyA implements Strategy {
 
  public function algorithmInterface() {
    echo 'algorithmInterface A<br />';
  }
}
 
/**
 * 具体策略角色B
 */
class ConcreteStrategyB implements Strategy {
 
  public function algorithmInterface() {
    echo 'algorithmInterface B<br />';
  }
}
 
/**
 * 具体策略角色C
 */
class ConcreteStrategyC implements Strategy {
 
  public function algorithmInterface() {
    echo 'algorithmInterface C<br />';
  }
}
 
/**
 * 环境角色
 */
class Context {
  /* 引用的策略 */
  private $_strategy;
 
  public function __construct(Strategy $strategy) {
    $this->_strategy = $strategy;
  }
 
  public function contextInterface() {
    $this->_strategy->algorithmInterface();
  }
 
}
 
/**
 * 客户端
 */
class Client {
 
  /**
   * Main program.
   */
  public static function main() {
    $strategyA = new ConcreteStrategyA();
    $context = new Context($strategyA);
    $context->contextInterface();
 
    $strategyB = new ConcreteStrategyB();
    $context = new Context($strategyB);
    $context->contextInterface();
 
    $strategyC = new ConcreteStrategyC();
    $context = new Context($strategyC);
    $context->contextInterface();
  }
 
}
 
Client::main();
?>