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策略模式、工厂模式以及Spring的InitializingBean消除IfElse

程序员文章站 2024-01-05 14:53:22
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计算价格接口:

package com.orchard.common.noIfElse;

import java.math.BigDecimal;

public interface  UserPayService {
    /**
     * 计算应付价格
     */
    public BigDecimal quote(BigDecimal orderPrice);
}

工程模式:

package com.orchard.common.noIfElse;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
import org.springframework.util.Assert;

import java.math.BigDecimal;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class UserPayServiceStrategyFactory {

    private static Map<String,UserPayService> services = new ConcurrentHashMap<String,UserPayService>();

    public  static UserPayService getByUserType(String type){
        return services.get(type);
    }

    public static void register(String userType,UserPayService userPayService){
        Assert.notNull(userType,"userType can't be null");
        services.put(userType,userPayService);
    }
}

@Service
class ParticularlyVipPayService implements UserPayService, InitializingBean {

    @Override
    public BigDecimal quote(BigDecimal orderPrice) {
        return orderPrice;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        UserPayServiceStrategyFactory.register("ParticularlyVip",this);
    }
}

@Service
class SuperVipPayService  implements UserPayService, InitializingBean {

    @Override
    public BigDecimal quote(BigDecimal orderPrice) {
        return orderPrice;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        UserPayServiceStrategyFactory.register("SuperVip",this);
    }
}

@Service
class VipPayService  implements UserPayService, InitializingBean {

    @Override
    public BigDecimal quote(BigDecimal orderPrice) {
        return orderPrice;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        UserPayServiceStrategyFactory.register("Vip",this);
    }
}

调用方法:

/**
 * @author mhcoding
 */
public BigDecimal calPrice(BigDecimal orderPrice,User user) {

     String vipType = user.getVipType();
     UserPayService strategy = UserPayServiceStrategyFactory.getByUserType(vipType);
     return strategy.quote(orderPrice);
}

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