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前言

在做統(tǒng)計(jì)的業(yè)務(wù)開發(fā)中，常常伴隨著用戶選擇不同類型的統(tǒng)計(jì)而動(dòng)態(tài)的加載數(shù)據(jù)，返回的數(shù)據(jù)也會(huì)動(dòng)態(tài)的改變，比如說一張商超里面可能有販賣肉蛋禽、蔬菜、飲料、水果等，我們需要根據(jù)這幾種類型指標(biāo)（算法不同）去生成各自的統(tǒng)計(jì)數(shù)據(jù)，如果根據(jù)不同的類型寫不同的接口，可以實(shí)簡單現(xiàn)該功能，但帶來的問題是接口定義太多，重復(fù)方法定義過多，如果統(tǒng)一一個(gè)接口、內(nèi)容使用if去走分支，也可以實(shí)現(xiàn)相同的效果，但還是不夠理想化，理想的是不需要手動(dòng)的添加if分支，而是做到自動(dòng)匹配到對應(yīng)算法執(zhí)行指定的流程，那么這時(shí)候就需要策略模式來幫我們實(shí)現(xiàn)這一步操作了

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一、策略模式是什么？

• 策略模式是一種行為型設(shè)計(jì)模式，它定義了一系列算法或策略，并將它們封裝起來，使它們可以互相替換。在使用策略模式時(shí)，可以通過改變不同的算法或策略來改變對象的行為。
• 策略模式通常包含兩部分：策略接口和策略實(shí)現(xiàn)類。策略接口定義了對某種行為的抽象，而策略實(shí)現(xiàn)類則提供了具體的算法或策略實(shí)現(xiàn)。

二、策略模式應(yīng)用場景

1. 針對同一類型問題的多種處理方式，僅僅是具體行為有差別時(shí)。
2. 需要?jiǎng)討B(tài)選擇算法和策略時(shí)。
3. 當(dāng)一個(gè)對象需要通過多種行為方式中的一種進(jìn)行某種操作時(shí)。
4. 在不希望客戶端知道具體實(shí)現(xiàn)細(xì)節(jié)的情況下，可采用策略模式對外提供接口。
5. 多個(gè)類只有在算法或行為上稍有不同的場景。
6. 假設(shè)有一個(gè)系統(tǒng)需要根據(jù)用戶的不同操作系統(tǒng)顯示不同的界面風(fēng)格?？梢允褂貌呗阅Ｊ?#xff0c;將不同操作系統(tǒng)的界面風(fēng)格作為不同的策略實(shí)現(xiàn)類，并通過定義一個(gè)策略接口來對外暴露相應(yīng)的方法。
7. 策略模式還可以用于設(shè)計(jì)游戲中的戰(zhàn)斗系統(tǒng)，根據(jù)不同角色的屬性和職業(yè)特點(diǎn)，選取最優(yōu)的戰(zhàn)斗策略進(jìn)行戰(zhàn)斗。
   總之，策略模式適用于多個(gè)類只有在算法或行為上稍有不同的場景，并且在運(yùn)行時(shí)需要?jiǎng)討B(tài)地選擇不同的算法或策略的情況下。

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三、策略模式優(yōu)點(diǎn)

1. 策略模式可以讓算法或策略獨(dú)立于使用它們的客戶端而變化，從而實(shí)現(xiàn)代碼復(fù)用。
2. 策略模式可以讓算法或策略在不影響代碼結(jié)構(gòu)的情況下靈活地變化，降低了代碼維護(hù)的成本。
3. 策略模式可以避免使用大量的 if-else 語句或者 switch 語句來進(jìn)行分支處理，增強(qiáng)了代碼的可讀性和可維護(hù)性。
4. 策略模式可以在運(yùn)行時(shí)動(dòng)態(tài)地改變算法或策略，因此可以根據(jù)需要進(jìn)行適當(dāng)?shù)倪x擇和組合。

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四、策略模式缺點(diǎn)

1. 策略模式會(huì)增加系統(tǒng)需要的類的數(shù)量，可能會(huì)導(dǎo)致代碼變得更加復(fù)雜和難以理解。
2. 策略模式需要客戶端了解不同的策略之間的差異，增加了客戶端的編碼難度。
3. 策略模式可能會(huì)導(dǎo)致不必要的運(yùn)行時(shí)開銷，因?yàn)樾枰獎(jiǎng)討B(tài)地選擇和組合算法或策略。

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五、場景案例：類型統(tǒng)計(jì)

1.項(xiàng)目結(jié)構(gòu)

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2.UML圖解

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3.代碼實(shí)現(xiàn)

3.1 指標(biāo)枚舉

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"),/*** 飲料*/BEVERAGE(4, "飲料", "beverageAnalysisTableService");/*** 編碼*/private final Integer code;/*** 注釋*/private final String desc;/*** 對應(yīng)策略*/private final String strategyName;
}

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3.2 請求體

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;/*** 統(tǒng)計(jì)圖Request*/
@Data
@ApiModel(value = "統(tǒng)計(jì)圖Request")
public class StatisticsRequest implements Serializable {private static final long serialVersionUID = 1L;@NotBlank(message = "統(tǒng)計(jì)指標(biāo)不能為空")@ApiModelProperty(value = "統(tǒng)計(jì)指標(biāo)")private StatisticalIndicatorsEnum statisticalIndicatorsEnum;@NotNull(message = "統(tǒng)計(jì)起始時(shí)間不能為空")@ApiModelProperty(value = "開始時(shí)間，格式：yyyy-MM-dd")@JsonFormat(pattern = "yyyy-MM-dd")private Date startDate;@NotNull(message = "統(tǒng)計(jì)截止時(shí)間不能為空")@ApiModelProperty(value = "結(jié)束時(shí)間（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 響應(yīng)體

import lombok.Data;/*** @author mxf* @version 1.0* @description: 響應(yīng)體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 = "統(tǒng)計(jì)時(shí)間")private String xDate;@ApiModelProperty(value = "飲料類型名稱")private String beverageTypeName;@ApiModelProperty(value = "銷售件數(shù)")private Double salesQuantity;@ApiModelProperty(value = "銷售金額")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 = "水果圖表響應(yīng)體")
@EqualsAndHashCode(callSuper = true)
public class FruitAvailabilityChartResponse extends BaseResponse implements Serializable {private static final long serialVersionUID = 1L;@ApiModelProperty(value = "統(tǒng)計(jì)時(shí)間")private String xDate;@ApiModelProperty(value = "本年銷售總額")private BigDecimal currentYearSalesAmount;@ApiModelProperty(value = "去年銷售金額")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 = "統(tǒng)計(jì)時(shí)間")private String xDate;@ApiModelProperty(value = "肉類名")private String fruitTypeName;@ApiModelProperty(value = "銷售量kg")private Double salesVolume;@ApiModelProperty(value = "銷售金額")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 = "統(tǒng)計(jì)時(shí)間")private String xDate;@ApiModelProperty(value = "肉類名")private String meatTypeName;@ApiModelProperty(value = "銷售量kg")private Double salesVolume;@ApiModelProperty(value = "銷售金額")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 = "統(tǒng)計(jì)時(shí)間")private String xDate;@ApiModelProperty(value = "肉類名")private String vegetableName;@ApiModelProperty(value = "銷售量kg")private Double salesVolume;@ApiModelProperty(value = "銷售金額")private BigDecimal salesAmount;
}

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3.4.分析統(tǒng)計(jì)指標(biāo)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;/*** 分析統(tǒng)計(jì)指標(biāo)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 指標(biāo)枚舉* @return com.mxf.code.strategy_factory.service.AnalysisTableService* @author mxf* @description 獲取實(shí)際統(tǒng)計(jì)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;/*** 統(tǒng)計(jì)分析*/
public interface AnalysisTableService {/*** 獲取統(tǒng)計(jì)圖數(shù)據(jù)** @param requestParams 入?yún)? @return*/List<BaseResponse> getChartData(StatisticsRequest statisticsRequest);/*** 獲取列表數(shù)據(jù)** @param requestParams 入?yún)? @return*/List<BaseResponse> getListData(StatisticsRequest statisticsRequest);
}

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3.6.擴(kuò)展接口

import com.mxf.code.strategy_factory.request.StatisticsRequest;/*** @author mxf* @version 1.0* @description: 水果(自定義接口)* @date 2023/5/26*/
public interface FruitAnalysisTableService {/*** 獲取水果庫存** @param statisticsRequest 入?yún)? @return*/Double getObtainInventory(StatisticsRequest statisticsRequest);
}

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3.7.接口實(shí)現(xiàn)

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: 飲料* @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.控制層

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: 統(tǒng)計(jì)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測試

1.測試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.測試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()擴(kuò)展接口

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

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總結(jié)

上述案例實(shí)現(xiàn)策略模式同時(shí)，針對入?yún)ⅰ⒊鰠ⅰ⒔涌跀U(kuò)展做了更好的兼容。