簡介

手寫了一個策略模式的簡單實現，當專案中出現很多if分支且每個分支處理的事情大致相同時可以考慮使用。

完整程式碼地址https://github.com/duzhuo/design-pattern/tree/master/design-pattern-strategy

其中列舉類的match寫法參考了xxl-job的com.xxl.job.admin.core.enums.ExecutorFailStrategyEnum。

程式執行方法

啟動springBoot專案

瀏覽器執行http://localhost:7777/01，走OrderService；

瀏覽器執行http://localhost:7777/02，走TransformService；

核心列舉類 BusinessTypeEnum

public enum BusinessTypeEnum {

    BUSINESS_ORDER("01", "訂單", "orderService"),
    BUSINESS_TRANS("02", "運單", "transformService");

    private String businessCode;
    private String businessName;
    private String serviceName;

    BusinessTypeEnum(String businessCode,
 
 String businessName, String serviceName) {
        this.businessCode = businessCode;
        this.businessName = businessName;
        this.serviceName = serviceName;
    }

    public String getBusinessCode() {
        return businessCode;
    }

    public String getServiceName() {
        return
 
 serviceName;
    }

    public static String match(String businessCode) {
        if (businessCode == null)
            return null;

        for (BusinessTypeEnum item : BusinessTypeEnum.values()) {
            if (item.getBusinessCode().equals(businessCode)) {
                return item.getServiceName();
            }
        }
        return null;
    }
}

執行器類BusinessExecutor

@Service
public class BusinessExecutor implements ApplicationContextAware {

    private ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    public String run(String businessCode) {
        String serviceName = BusinessTypeEnum.match(businessCode);

        if (serviceName == null) {
            return "not match this business!!";
        }

        BusinessService businessService = (BusinessService) applicationContext.getBean(serviceName);
        return businessService.dealBusiness();
    }
}

業務介面與實現

public interface BusinessService {

    String dealBusiness();
}


@Service
public class OrderService implements BusinessService {
    @Override
    public String dealBusiness() {
        return "this is OrderService";
    }
}

@Service
public class TransformService implements BusinessService {
    @Override
    public String dealBusiness() {
        return "this is TransformService";
    }
}

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