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;
    }
}

---

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;
}

---

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());
    }
}

---

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);
}

---

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);
}

---

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 {

    @Override
    public List<BaseResponse> getChartData(StatisticsRequest requestParams) {
        return null;
    }

    @Override
    public 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 {
    @Override
    public 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);
    }

    @Override
    public 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);
    }

    @Override
    public 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 {
    @Override
    public List<BaseResponse> getChartData(StatisticsRequest requestParams) {
        return null;
    }

    @Override
    public 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 {
    @Override
    public List<BaseResponse> getChartData(StatisticsRequest requestParams) {
        return null;
    }

    @Override
    public 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 {

    @Autowired
    private AnalysisTableStrategyContext analysisTableStrategyContext;
    @Autowired
    private 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);
}

---

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);
}

---

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。