策略模式-类型统计

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前言

在做统计的业务开发中，常常伴随着用户选择不同类型的统计而动态的加载数据，返回的数据也会动态的改变，比如说一张商超里面可能有贩卖肉蛋禽、蔬菜、饮料、水果等，我们需要根据这几种类型指标（算法不同）去生成各自的统计数据，如果根据不同的类型写不同的接口，可以实简单现该功能，但带来的问题是接口定义太多，重复方法定义过多，如果统一一个接口、内容使用if去走分支，也可以实现相同的效果，但还是不够理想化，理想的是不需要手动的添加if分支，而是做到自动匹配到对应算法执行指定的流程，那么这时候就需要策略模式来帮我们实现这一步操作了

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一、策略模式是什么？

• 策略模式是一种行为型设计模式，它定义了一系列算法或策略，并将它们封装起来，使它们可以互相替换。在使用策略模式时，可以通过改变不同的算法或策略来改变对象的行为。
• 策略模式通常包含两部分：策略接口和策略实现类。策略接口定义了对某种行为的抽象，而策略实现类则提供了具体的算法或策略实现。

二、策略模式应用场景

1. 针对同一类型问题的多种处理方式，仅仅是具体行为有差别时。
2. 需要动态选择算法和策略时。
3. 当一个对象需要通过多种行为方式中的一种进行某种操作时。
4. 在不希望客户端知道具体实现细节的情况下，可采用策略模式对外提供接口。
5. 多个类只有在算法或行为上稍有不同的场景。
6. 假设有一个系统需要根据用户的不同操作系统显示不同的界面风格。可以使用策略模式，将不同操作系统的界面风格作为不同的策略实现类，并通过定义一个策略接口来对外暴露相应的方法。
7. 策略模式还可以用于设计游戏中的战斗系统，根据不同角色的属性和职业特点，选取最优的战斗策略进行战斗。
   总之，策略模式适用于多个类只有在算法或行为上稍有不同的场景，并且在运行时需要动态地选择不同的算法或策略的情况下。

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三、策略模式优点

1. 策略模式可以让算法或策略独立于使用它们的客户端而变化，从而实现代码复用。
2. 策略模式可以让算法或策略在不影响代码结构的情况下灵活地变化，降低了代码维护的成本。
3. 策略模式可以避免使用大量的 if-else 语句或者 switch 语句来进行分支处理，增强了代码的可读性和可维护性。
4. 策略模式可以在运行时动态地改变算法或策略，因此可以根据需要进行适当的选择和组合。

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四、策略模式缺点

1. 策略模式会增加系统需要的类的数量，可能会导致代码变得更加复杂和难以理解。
2. 策略模式需要客户端了解不同的策略之间的差异，增加了客户端的编码难度。
3. 策略模式可能会导致不必要的运行时开销，因为需要动态地选择和组合算法或策略。

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五、场景案例：类型统计

1.项目结构

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2.UML图解

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3.代码实现

3.1 指标枚举

import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.AllArgsConstructor;
import lombok.Getter;@Getter
@AllArgsConstructor
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum StatisticalIndicatorsEnum {/*** 肉*/MEAT(1, "肉", "meatAnalysisTableService"),/*** 水果*/FRUIT(2, "水果", "fruitAnalysisTableService"),/*** 蔬菜*/VEGETABLE(3, "蔬菜", "vegetableAnalysisTableService"),/*** 饮料*/BEVERAGE(4, "饮料", "beverageAnalysisTableService");/*** 编码*/private final Integer code;/*** 注释*/private final String desc;/*** 对应策略*/private final String strategyName;
}

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3.2 请求体

import com.fasterxml.jackson.annotation.JsonFormat;
import com.mxf.code.strategy_factory.enums.StatisticalIndicatorsEnum;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import org.springframework.web.bind.annotation.ModelAttribute;import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;
import java.io.Serializable;
import java.util.Date;/*** 统计图Request*/
@Data
@ApiModel(value = "统计图Request")
public class StatisticsRequest implements Serializable {private static final long serialVersionUID = 1L;@NotBlank(message = "统计指标不能为空")@ApiModelProperty(value = "统计指标")private StatisticalIndicatorsEnum statisticalIndicatorsEnum;@NotNull(message = "统计起始时间不能为空")@ApiModelProperty(value = "开始时间，格式：yyyy-MM-dd")@JsonFormat(pattern = "yyyy-MM-dd")private Date startDate;@NotNull(message = "统计截止时间不能为空")@ApiModelProperty(value = "结束时间（格式：yyyy-MM-dd）")@JsonFormat(pattern = "yyyy-MM-dd")private Date endDate;@ModelAttribute("statisticalIndicators")public void setStatisticalIndicatorsEnum(StatisticalIndicatorsEnum statisticalIndicatorsEnum) {this.statisticalIndicatorsEnum = statisticalIndicatorsEnum;}
}

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3.3 响应体

import lombok.Data;/*** @author mxf* @version 1.0* @description: 响应体Base* @date 2023/5/26*/
@Data
public abstract class BaseResponse {
}

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;import java.io.Serializable;
import java.math.BigDecimal;/*** @author 28382*/
@Data
@ApiModel(value = "蔬菜")
@EqualsAndHashCode(callSuper = true)
public class BeverageAvailabilityListResponse extends BaseResponse implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty(value = "统计时间")private String xDate;@ApiModelProperty(value = "饮料类型名称")private String beverageTypeName;@ApiModelProperty(value = "销售件数")private Double salesQuantity;@ApiModelProperty(value = "销售金额")private BigDecimal salesAmount;
}

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;import java.io.Serializable;
import java.math.BigDecimal;/*** @author 28382*/
@Data
@ApiModel(value = "水果图表响应体")
@EqualsAndHashCode(callSuper = true)
public class FruitAvailabilityChartResponse extends BaseResponse implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty(value = "统计时间")private String xDate;@ApiModelProperty(value = "本年销售总额")private BigDecimal currentYearSalesAmount;@ApiModelProperty(value = "去年销售金额")private BigDecimal previousYearSalesAmount;
}

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;import java.io.Serializable;
import java.math.BigDecimal;/*** @author 28382*/
@Data
@ApiModel(value = "水果")
@EqualsAndHashCode(callSuper = true)
public class FruitAvailabilityListResponse extends BaseResponse implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty(value = "统计时间")private String xDate;@ApiModelProperty(value = "肉类名")private String fruitTypeName;@ApiModelProperty(value = "销售量kg")private Double salesVolume;@ApiModelProperty(value = "销售金额")private BigDecimal salesAmount;
}

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;import java.io.Serializable;
import java.math.BigDecimal;/*** @author 28382*/
@Data
@ApiModel(value = "肉")
@EqualsAndHashCode(callSuper = true)
public class MeatAvailabilityListResponse extends BaseResponse implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty(value = "统计时间")private String xDate;@ApiModelProperty(value = "肉类名")private String meatTypeName;@ApiModelProperty(value = "销售量kg")private Double salesVolume;@ApiModelProperty(value = "销售金额")private BigDecimal salesAmount;
}

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import lombok.EqualsAndHashCode;import java.io.Serializable;
import java.math.BigDecimal;/*** @author 28382*/
@Data
@ApiModel(value = "蔬菜")
@EqualsAndHashCode(callSuper = true)
public class VegetableAvailabilityListResponse extends BaseResponse implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty(value = "统计时间")private String xDate;@ApiModelProperty(value = "肉类名")private String vegetableName;@ApiModelProperty(value = "销售量kg")private Double salesVolume;@ApiModelProperty(value = "销售金额")private BigDecimal salesAmount;
}

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3.4.分析统计指标策略

管理策略bean

import com.mxf.code.strategy_factory.enums.StatisticalIndicatorsEnum;
import org.springframework.stereotype.Service;import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;/*** 分析统计指标策略** @author 28382*/
@Service
public class AnalysisTableStrategyContext {private final Map<String, AnalysisTableService> analysisTableMap = new ConcurrentHashMap<>();public AnalysisTableStrategyContext(Map<String, AnalysisTableService> strategyMap) {this.analysisTableMap.putAll(strategyMap);}/*** @param statisticalIndicatorsEnum 指标枚举* @return com.mxf.code.strategy_factory.service.AnalysisTableService* @author mxf* @description 获取实际统计策略* @createTime 2023/5/26 14:08* @paramType [com.mxf.code.strategy_factory.enums.StatisticalIndicatorsEnum]*/public AnalysisTableService getResource(StatisticalIndicatorsEnum statisticalIndicatorsEnum) {return analysisTableMap.get(statisticalIndicatorsEnum.getStrategyName());}
}

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3.5.接口

import com.mxf.code.strategy_factory.request.StatisticsRequest;
import com.mxf.code.strategy_factory.response.BaseResponse;import java.util.List;/*** 统计分析*/
public interface AnalysisTableService {/*** 获取统计图数据** @param requestParams 入参* @return*/List<BaseResponse> getChartData(StatisticsRequest statisticsRequest);/*** 获取列表数据** @param requestParams 入参* @return*/List<BaseResponse> getListData(StatisticsRequest statisticsRequest);
}

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3.6.扩展接口

import com.mxf.code.strategy_factory.request.StatisticsRequest;/*** @author mxf* @version 1.0* @description: 水果(自定义接口)* @date 2023/5/26*/
public interface FruitAnalysisTableService {/*** 获取水果库存** @param statisticsRequest 入参* @return*/Double getObtainInventory(StatisticsRequest statisticsRequest);
}

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3.7.接口实现

import com.mxf.code.strategy_factory.request.StatisticsRequest;
import com.mxf.code.strategy_factory.response.BaseResponse;
import com.mxf.code.strategy_factory.response.BeverageAvailabilityListResponse;
import com.mxf.code.strategy_factory.service.AnalysisTableService;
import org.springframework.stereotype.Service;import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;/*** @author mxf* @version 1.0* @description: 饮料* @date 2023/5/26*/
@Service("beverageAnalysisTableService")
public class BeverageAnalysisTableServiceImpl implements AnalysisTableService {@Overridepublic List<BaseResponse> getChartData(StatisticsRequest requestParams) {return null;}@Overridepublic List<BaseResponse> getListData(StatisticsRequest statisticsRequest) {List<BeverageAvailabilityListResponse> resultList = new ArrayList<>();BeverageAvailabilityListResponse beverageAvailabilityListResponse = new BeverageAvailabilityListResponse();beverageAvailabilityListResponse.setXDate("");beverageAvailabilityListResponse.setBeverageTypeName("");beverageAvailabilityListResponse.setSalesQuantity(0.0D);beverageAvailabilityListResponse.setSalesAmount(new BigDecimal("0"));resultList.add(beverageAvailabilityListResponse);return new ArrayList<>(resultList);}
}

import com.mxf.code.strategy_factory.request.StatisticsRequest;
import com.mxf.code.strategy_factory.response.BaseResponse;
import com.mxf.code.strategy_factory.response.FruitAvailabilityChartResponse;
import com.mxf.code.strategy_factory.response.FruitAvailabilityListResponse;
import com.mxf.code.strategy_factory.service.AnalysisTableService;
import com.mxf.code.strategy_factory.service.FruitAnalysisTableService;
import org.springframework.stereotype.Service;import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;/*** @author mxf* @version 1.0* @description: 水果* @date 2023/5/26*/
@Service("fruitAnalysisTableService")
public class FruitAnalysisTableServiceImpl implements AnalysisTableService, FruitAnalysisTableService {@Overridepublic List<BaseResponse> getChartData(StatisticsRequest requestParams) {List<FruitAvailabilityChartResponse> resultList = new ArrayList<>();FruitAvailabilityChartResponse fruitAvailabilityChartResponse = new FruitAvailabilityChartResponse();fruitAvailabilityChartResponse.setXDate("2022-05-25");fruitAvailabilityChartResponse.setCurrentYearSalesAmount(new BigDecimal("4"));fruitAvailabilityChartResponse.setPreviousYearSalesAmount(new BigDecimal("5"));FruitAvailabilityChartResponse fruitAvailabilityChartResponse2 = new FruitAvailabilityChartResponse();fruitAvailabilityChartResponse2.setXDate("2022-05-26");fruitAvailabilityChartResponse2.setCurrentYearSalesAmount(new BigDecimal("1"));fruitAvailabilityChartResponse2.setPreviousYearSalesAmount(new BigDecimal("2"));resultList.add(fruitAvailabilityChartResponse);resultList.add(fruitAvailabilityChartResponse2);return new ArrayList<>(resultList);}@Overridepublic List<BaseResponse> getListData(StatisticsRequest statisticsRequest) {List<FruitAvailabilityListResponse> resultList = new ArrayList<>();FruitAvailabilityListResponse fruitAvailabilityListResponse = new FruitAvailabilityListResponse();fruitAvailabilityListResponse.setXDate("");fruitAvailabilityListResponse.setFruitTypeName("");fruitAvailabilityListResponse.setSalesVolume(0.0D);fruitAvailabilityListResponse.setSalesAmount(new BigDecimal("0"));resultList.add(fruitAvailabilityListResponse);return new ArrayList<>(resultList);}@Overridepublic Double getObtainInventory(StatisticsRequest statisticsRequest) {return 334423423.44;}
}

import com.mxf.code.strategy_factory.request.StatisticsRequest;
import com.mxf.code.strategy_factory.response.BaseResponse;
import com.mxf.code.strategy_factory.response.MeatAvailabilityListResponse;
import com.mxf.code.strategy_factory.service.AnalysisTableService;
import org.springframework.stereotype.Service;import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;/*** @author mxf* @version 1.0* @description: 肉* @date 2023/5/26*/
@Service("meatAnalysisTableService")
public class MeatAnalysisTableServiceImpl implements AnalysisTableService {@Overridepublic List<BaseResponse> getChartData(StatisticsRequest requestParams) {return null;}@Overridepublic List<BaseResponse> getListData(StatisticsRequest statisticsRequest) {List<MeatAvailabilityListResponse> resultList = new ArrayList<>();MeatAvailabilityListResponse meatAvailabilityListResponse = new MeatAvailabilityListResponse();meatAvailabilityListResponse.setXDate("");meatAvailabilityListResponse.setMeatTypeName("");meatAvailabilityListResponse.setSalesVolume(0.0D);meatAvailabilityListResponse.setSalesAmount(new BigDecimal("0"));resultList.add(meatAvailabilityListResponse);return new ArrayList<>(resultList);}
}

import com.mxf.code.strategy_factory.request.StatisticsRequest;
import com.mxf.code.strategy_factory.response.BaseResponse;
import com.mxf.code.strategy_factory.response.VegetableAvailabilityListResponse;
import com.mxf.code.strategy_factory.service.AnalysisTableService;
import org.springframework.stereotype.Service;import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;/*** @author mxf* @version 1.0* @description: 蔬菜* @date 2023/5/26*/
@Service("vegetableAnalysisTableService")
public class VegetableAnalysisTableServiceImpl implements AnalysisTableService {@Overridepublic List<BaseResponse> getChartData(StatisticsRequest requestParams) {return null;}@Overridepublic List<BaseResponse> getListData(StatisticsRequest statisticsRequest) {List<VegetableAvailabilityListResponse> resultList = new ArrayList<>();VegetableAvailabilityListResponse vegetableAvailabilityListResponse = new VegetableAvailabilityListResponse();vegetableAvailabilityListResponse.setXDate("");vegetableAvailabilityListResponse.setVegetableName("");vegetableAvailabilityListResponse.setSalesVolume(0.0D);vegetableAvailabilityListResponse.setSalesAmount(new BigDecimal("0"));resultList.add(vegetableAvailabilityListResponse);return new ArrayList<>(resultList);}
}

3.8.控制层

import com.mxf.code.strategy_factory.request.StatisticsRequest;
import com.mxf.code.strategy_factory.response.BaseResponse;
import com.mxf.code.strategy_factory.service.AnalysisTableService;
import com.mxf.code.strategy_factory.service.AnalysisTableStrategyContext;
import com.mxf.code.strategy_factory.service.FruitAnalysisTableService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.Assert;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.List;/*** @author mxf* @version 1.0* @description: 统计分析* @date 2023/5/26*/
@RestController
@RequestMapping("statistical/indicators")
public class StatisticalIndicatorsController {@Autowiredprivate AnalysisTableStrategyContext analysisTableStrategyContext;@Autowiredprivate FruitAnalysisTableService fruitAnalysisTableService;@GetMapping("listData")public List<BaseResponse> getListData(StatisticsRequest statisticsRequest) {AnalysisTableService resource = analysisTableStrategyContext.getResource(statisticsRequest.getStatisticalIndicatorsEnum());Assert.notNull(resource, "未知策略");return resource.getListData(statisticsRequest);}@GetMapping("chartData")public List<BaseResponse> getchartData(StatisticsRequest statisticsRequest) {AnalysisTableService resource = analysisTableStrategyContext.getResource(statisticsRequest.getStatisticalIndicatorsEnum());Assert.notNull(resource, "未知策略");return resource.getChartData(statisticsRequest);}@GetMapping("getFruitObtainInventory")public Double getFruitObtainInventory(StatisticsRequest statisticsRequest) {return fruitAnalysisTableService.getObtainInventory(statisticsRequest);}
}

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六、PostMan测试

1.测试getListData()接口

@GetMapping("listData")
public List<BaseResponse> getListData(StatisticsRequest statisticsRequest) {AnalysisTableService resource = analysisTableStrategyContext.getResource(statisticsRequest.getStatisticalIndicatorsEnum());Assert.notNull(resource, "未知策略");return resource.getListData(statisticsRequest);
}

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2.测试getChartData()接口

@GetMapping("chartData")
public List<BaseResponse> getchartData(StatisticsRequest statisticsRequest) {AnalysisTableService resource = analysisTableStrategyContext.getResource(statisticsRequest.getStatisticalIndicatorsEnum());Assert.notNull(resource, "未知策略");return resource.getChartData(statisticsRequest);
}

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3.getObtainInventory()扩展接口

@GetMapping("getFruitObtainInventory")public Double getFruitObtainInventory(StatisticsRequest statisticsRequest) {return fruitAnalysisTableService.getObtainInventory(statisticsRequest);}

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总结

上述案例实现策略模式同时，针对入参、出参、接口扩展做了更好的兼容。