java design patterns - Strategy (2)

Outlook has static factory + strategy handle multiple if judgment

Project Demo

Look at the final calling code

@RestController
public class DemoController {

    @PostMapping(value = "/strategy/factory/pay")
    public String pay(@RequestParam String payType) {

        StrategyFactory strategyFactory = StrategyFactory.getInstance();

        Pay pay = strategyFactory.get(payType);

        String call = pay.call();

        System.out.println(call);

        return pay.call();

    }
}

The definition of common interface

public interface Pay {

    String call();

    String getType();
}

public class AliPay implements Pay {

    @Override
    public String call() {
        System.out.println("调用支付宝");
        return "ali";
    }

    @Override
    public String getType() {
        return PayConstant.ali_pay.name();
    }
}

public class UnionPay implements Pay {

    @Override
    public String call() {
        System.out.println("调用银联");
        return "union";
    }

    @Override
    public String getType() {
        return PayConstant.union_pay.name();
    }
}

public class WxPay implements Pay {

    @Override
    public String call() {
        System.out.println("调用微信");
        return "wx";
    }

    @Override
    public String getType() {
        return PayConstant.wx_pay.name();
    }
}

Enumeration constant

public enum PayConstant {

    ali_pay,
    wx_pay,
    union_pay;
}

Custom Factory

public class StrategyFactory {

    private Map<String, Pay> map;

    public StrategyFactory() {

        List<Pay> pays = new ArrayList<>();
        pays.add(new AliPay());
        pays.add(new WxPay());
        pays.add(new UnionPay());

        map = pays.stream().collect(Collectors.toMap(Pay::getType,strategy-> strategy));
    }

    public static StrategyFactory getInstance() {
        return PayStrategyFactory.instance;
    }

    public Pay get(String type) {

        return map.get(type);
    }

    public static class PayStrategyFactory{

        public static StrategyFactory instance = new StrategyFactory();

    }
}

Project Demo

Renderings

• request
  
• Console Print

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