一、简介
1、定义
策略模式（Strategy Pattern）是一种行为设计模式，它定义一系列算法，将每一个算法封装起来，算法之间可以相互替换。通过定义策略接口和具体策略实现类，将算法封装为对象，并在运行时选择对应的算法。
2、策略模式的结构
策略模式涉及以下几个角色：
策略(Strategy)接口：提供所有的具体策略类所需的接口。
具体策略(ConcreteStrategy)实现：实现策略接口，包装了相关的算法。
环境(Context)：维护策略，调用对应的策略。
二、Java实现案例
1、策略模式通用案例
java">/*** @Description: 策略接口* @Date: 2025-02-08 13:16* @Author: gaoyufei**/
public interface Strategy {void execute();
}/*** @Description: 具体策略A* @Date: 2025-02-08 13:17* @Author: gaoyufei**/
public class ConcreteStrategyA implements Strategy{@Overridepublic void execute() {System.out.println("执行具体策略A");}
}/*** @Description: 具体策略B* @Date: 2025-02-08 13:17* @Author: gaoyufei**/
public class ConcreteStrategyB implements Strategy{@Overridepublic void execute() {System.out.println("执行具体策略B");}
}/*** @Description: 上下文类* @Date: 2025-02-08 13:18* @Author: gaoyufei**/
public class Context {private Strategy strategy;public Context(Strategy strategy){this.strategy=strategy;}public void setStrategy(Strategy strategy){this.strategy=strategy;}public void executeStrategy(){strategy.execute();}
}/*** @Description: 客户端* @Date: 2025-02-08 13:20* @Author: gaoyufei**/
public class ClientMain {public static void main(String[] args) {Context context=new Context(new ConcreteStrategyA());context.executeStrategy();context.setStrategy(new ConcreteStrategyB());context.executeStrategy();}
}
2、加减乘除运算策略案例
java">/*** @Description: 运算接口* @Date: 2025-02-08 13:32* @Author: gaoyufei**/
public interface Operation {int execute(int a, int b);
}
/*** @Description: 加法运算* @Date: 2025-02-08 13:33* @Author: gaoyufei**/
public class AddOperation implements Operation{@Overridepublic int execute(int a, int b) {return a+b;}
}
/*** @Description: 减法运算* @Date: 2025-02-08 13:33* @Author: gaoyufei**/
public class SubOperation implements Operation{@Overridepublic int execute(int a, int b) {return a-b;}
}
/*** @Description: 乘法运算* @Date: 2025-02-08 13:34* @Author: gaoyufei**/
public class MultiOperation implements Operation{@Overridepublic int execute(int a, int b) {return a*b;}
}
/*** @Description: 除法运算* @Date: 2025-02-08 13:34* @Author: gaoyufei**/
public class DivOperation implements Operation{@Overridepublic int execute(int a, int b) {return a/b;}
}import java.util.HashMap;
import java.util.Map;
import java.util.Optional;/*** @Description: 操作者工厂类* @Date: 2025-02-08 13:35* @Author: gaoyufei**/
public class OperatorFactory {private static Map<String, Operation> map=new HashMap<>();static {map.put("+",new AddOperation());map.put("-",new SubOperation());map.put("*",new MultiOperation());map.put("/",new DivOperation());}public static Optional<Operation> getOperation(String operator){return Optional.ofNullable(map.get(operator));}
}/*** @Description: 测试类* @Date: 2025-02-08 13:39* @Author: gaoyufei**/
public class OperatorTestMain {public static void main(String[] args) {Operation add = OperatorFactory.getOperation("+").orElseThrow(() -> new IllegalArgumentException("无效操作"));int addRes = add.execute(2, 3);System.out.println("2+3="+addRes);Operation sub = OperatorFactory.getOperation("-").orElseThrow(() -> new IllegalArgumentException("无效操作"));int subRes = sub.execute(5, 1);System.out.println("5-1="+subRes);Operation multi = OperatorFactory.getOperation("*").orElseThrow(() -> new IllegalArgumentException("无效操作"));int multiRes = multi.execute(2, 2);System.out.println("2*2="+multiRes);Operation div = OperatorFactory.getOperation("/").orElseThrow(() -> new IllegalArgumentException("无效操作"));int divRes = div.execute(6, 2);System.out.println("6/2="+divRes);}
}
3、springboot项目策略模式实现
java">/*** @Description: Strategy* @Date: 2025-02-08 14:40* @Author: gaoyufei**/
public interface Strategy {void method();
}import org.springframework.stereotype.Service;
/*** @Description: 策略A* @Date: 2025-02-08 14:40* @Author: gaoyufei**/
@Service("strategyA")
public class StrategyA implements Strategy{@Overridepublic void method() {System.out.println("实现策略A方法");}
}import org.springframework.stereotype.Service;
/*** @Description: 策略B* @Date: 2025-02-08 14:40* @Author: gaoyufei**/
@Service("strategyB")
public class StrategyB implements Strategy{@Overridepublic void method() {System.out.println("实现策略B方法");}
}import org.springframework.stereotype.Service;
/*** @Description: 策略C* @Date: 2025-02-08 14:40* @Author: gaoyufei**/
@Service("strategyC")
public class StrategyC implements Strategy{@Overridepublic void method() {System.out.println("实现策略C方法");}
}/*** @Description: 策略枚举* @Date: 2025-02-08 14:43* @Author: gaoyufei**/
public enum StrategyEnum {strategyA(1,"strategyA"),strategyB(2,"strategyB"),strategyC(3,"strategyC");private Integer code;private String name;public Integer getCode() {return code;}public String getName() {return name;}StrategyEnum(Integer code, String name){this.code=code;this.name=name;}public static String getName(Integer code){StrategyEnum[] enums = StrategyEnum.values();for(int i=0;i<enums.length;i++){if(enums[i].getCode().equals(code)){return enums[i].getName();}}return null;}
}import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;import javax.annotation.PostConstruct;
import java.util.HashMap;
import java.util.Map;/*** @Description: StrategyContext* @Date: 2025-02-08 14:50* @Author: gaoyufei**/
@Component
public class StrategyContext {private static Map<String,Strategy> strategyMap=new HashMap<>();@Autowiredprivate ApplicationContext applicationContext;@PostConstructpublic void init(){strategyMap.putAll(applicationContext.getBeansOfType(Strategy.class));}public Strategy getStrategy(Integer code){return strategyMap.get(StrategyEnum.getName(code));}
}import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;/*** @Description: StrategyController* @Date: 2025-02-08 14:57* @Author: gaoyufei**/
@RestController
public class StrategyController {@Autowiredprivate StrategyContext strategyContext;@RequestMapping("/method")public void testMethod(@RequestParam("code") Integer code){Strategy strategy = strategyContext.getStrategy(code);if(strategy!=null) {strategy.method();}}
}
