设计模式使用简例（简单工厂+策略模式+模板方法）

直接上代码，方便记忆。主要的要点，已经写到注释中。

一，代码展示

启动类

package com.rojer;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}
}

controller

package com.rojer.factoryMoudle.controller;import com.rojer.factoryMoudle.PaymentStrategyFactory;
import com.rojer.factoryMoudle.impl.pay.AliPay;
import com.rojer.factoryMoudle.impl.pay.UnionPay;
import com.rojer.factoryMoudle.impl.pay.WechatPay;
import com.rojer.factoryMoudle.impl.pay.abs.AbstractPaymentStrategy;
import com.rojer.factoryMoudle.moudle.PayModule;
import com.rojer.factoryMoudle.impl.pay.inter.PaymentStrategy;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/")
public class PayController {@Autowiredprivate PaymentStrategyFactory paymentStrategyFactory;/*** 普通写发法* @param module*/@PostMapping("/online/pay1")public void pay(@RequestBody PayModule module) {PaymentStrategy paymentStrategy;switch (module.getPayType()) {case 1:paymentStrategy = new AliPay();break;case 2:paymentStrategy = new WechatPay();break;case 3:paymentStrategy = new UnionPay();break;default:throw new IllegalArgumentException("无效的支付类型");}paymentStrategy.pay(module.getPayAmount());}/*** 改造后写法* @param module*/@PostMapping("/online/pay2")public void pay2(@RequestBody PayModule module) {AbstractPaymentStrategy strategy = paymentStrategyFactory.getPaymentStrategy(module.getPayType());strategy.commonPay(module.getPayAmount());}}

策略接口

package com.rojer.factoryMoudle.impl.pay.inter;import java.math.BigDecimal;/*** 策略模式接口*/
public interface PaymentStrategy {void pay(BigDecimal amount);
}

策略实现类

阿里支付类

package com.rojer.factoryMoudle.impl.pay;import com.rojer.factoryMoudle.impl.pay.abs.AbstractPaymentStrategy;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;import java.math.BigDecimal;/*** 具体的策略实现AliPay*/
@Component
public class AliPay extends AbstractPaymentStrategy {// 可注入别的类// @Autowired// private Pay pay;@Overridepublic void pay(BigDecimal amount) {System.out.println("进行了阿里支付");}
}

银联支付类

package com.rojer.factoryMoudle.impl.pay;import com.rojer.factoryMoudle.impl.pay.abs.AbstractPaymentStrategy;
import org.springframework.stereotype.Component;import java.math.BigDecimal;/*** 具体的策略实现UnionPay*/
@Component
public class UnionPay extends AbstractPaymentStrategy {// 可注入别的类// @Autowired// private Pay pay;@Overridepublic void pay(BigDecimal amount) {System.out.println("进行了银联支付");}
}

微信支付类

package com.rojer.factoryMoudle.impl.pay;import com.rojer.factoryMoudle.impl.pay.abs.AbstractPaymentStrategy;
import org.springframework.stereotype.Component;import java.math.BigDecimal;/*** 具体的策略实现WechatPay*/
@Component
public class WechatPay extends AbstractPaymentStrategy {// 可注入别的类// @Autowired// private Pay pay;@Overridepublic void pay(BigDecimal amount) {System.out.println("进行了微信支付");}
}

简单工厂

package com.rojer.factoryMoudle;import com.rojer.factoryMoudle.impl.pay.AliPay;
import com.rojer.factoryMoudle.impl.pay.UnionPay;
import com.rojer.factoryMoudle.impl.pay.WechatPay;
import com.rojer.factoryMoudle.impl.pay.abs.AbstractPaymentStrategy;
import com.rojer.factoryMoudle.moudle.PayEnum;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;/*** 设计模式之简单工厂*/
@Component
public class PaymentStrategyFactory implements ApplicationContextAware {private ApplicationContext applicationContext;/*** 使用简单工厂生成具体的支付对学校** @param payType 支付类型* @return AbstractPaymentStrategy 抽象支付类*/public AbstractPaymentStrategy getPaymentStrategy(Integer payType) {if (PayEnum.ALIPAY.getCode() == payType) {return applicationContext.getBean(AliPay.class);} else if (PayEnum.WECHATPAY.getCode() == payType){return applicationContext.getBean(WechatPay.class);} else if (PayEnum.UNIONPAY.getCode() == payType) {return applicationContext.getBean(UnionPay.class);} else {throw new IllegalArgumentException("无效的支付类型");}}@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {this.applicationContext = applicationContext;}
}

模板方法

package com.rojer.factoryMoudle.impl.pay.abs;import com.rojer.factoryMoudle.impl.pay.inter.PaymentStrategy;import java.math.BigDecimal;/*** 设计模式之模板方法* 定义了支付的模板方法*/
public abstract class AbstractPaymentStrategy implements PaymentStrategy {// 模板方法public final void commonPay(BigDecimal amount) {// 检测金额未合法数字check(amount);// 扩展支付pay(amount);// 可以继续扩展模板}// 声明未private，该方法不可被重写，必须按这个进行private void check(BigDecimal amount) {if (amount.compareTo(BigDecimal.ZERO) < 0) {throw new IllegalArgumentException("无效的金额！");}}
}

module类

package com.rojer.factoryMoudle.moudle;public enum PayEnum {ALIPAY(1, "Alipay"),WECHATPAY(2, "WeChat Pay"),UNIONPAY(3, "UnionPay");private final int code;private final String description;PayEnum(int code, String description) {this.code = code;this.description = description;}public int getCode() {return code;}public String getDescription() {return description;}}

package com.rojer.factoryMoudle.moudle;import lombok.Data;import java.math.BigDecimal;@Data
public class PayModule {private Integer payType;private BigDecimal payAmount;
}