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本文介绍项目中常用的策略模式+工厂模式的案例，该案例是针对策略类比较少的情况；下一篇会讲解策略类比较多的案例，下面直接开始：

案例1：项目中对系统中的客户和销售进行事件通知(短信、邮件、钉钉)

首先要有通知的策略接口，接口里面要有一个方法就是通知的方法

public interface PushChannelStrategy｛// 通知方法SendResult send(MessagePushParam param，BaseMsg baseMsg）;｝

有了接口那必然有实现类，三个实现类短信、邮件、钉钉

短信：

@Slf4j
@Component
public class SmsPushChannelStrategy implements PushChannelStrategy｛@Autowiredprivate NoticeClient noticeClient；@Overridepublic SendResult send（MessagePushParam param，BaseMsg baseMsg）｛//1、before send check//2、send smsNoticeResult noticeResult=noticeClient.sendSms（xxxx）；sendResult.setMessageStatus（MessageStatusEnum.SUCCESS）；return sendResult；｝
｝

邮件：

@Slf4j
@Component
public class EmailPushChannelStrategy implements PushChannelStrategy｛@Autowiredprivate NoticeClient noticeClient；@Overridepublic SendResult send（MessagePushParam param，BaseMsg baseMsg）｛//1、before send check//2、send emailEmail emailMsg=(Email)baseMsg；NoticeResult noticeResult=noticeClient.sendEmail（xxxx）；sendResult.setMessageStatus（MessageStatusEnum.SUCCESS）；return sendResult；｝
｝

钉钉：

@Slf4j
@Component
public class DingTalkPushChannelStrategy implements PushChannelStrategy｛@Autowiredprivate DingTalkClient dingTalkClient；@Overridepublic SendResult send（MessagePushParam param，BaseMsg baseMsg）｛//1、before send check//2、send ding talkSendResult sendResult=dingTalkClient.send(xxx)；// 其他结果参数组装return sendResult；｝
｝

然后通过策略工厂来获取具体的策略类：(由于只有三个策略类，所以通过注入的方式对channel进行判断)

@Component
public class PushChannelStrategyFactory｛@Autowired private DingTalkPushChannelStrategy dingTalkPushChannelStrategy；@Autowiredprivate SmsPushChannelStrategy smsPushChannelStrategy；@Autowiredprivate EmailPushChannelStrategy emailPushChannelStrategy；public PushChannelStrategy getStrategy(PushChannel pushChannel)｛switch(pushChannel)｛case DING_TALK：return dingTalkPushChannelStrategy；case SMS：return smsPushChannelStrategy；case EMAIL：return emailPushChannelStrategy；default：throw new RuntimeException(＂不支持的类型＂)；｝｝
｝

当然策略工厂针对策略实现类比较少的情况还可以这样写：

@Component
public class PushChannelStrategyFactory2｛@Autowiredprivate DingTalkPushChannelStrategy dingTalkPushChannelStrategy;@Autowiredprivate SmsPushChannelStrategy smsPushChannelStrategy;@Autowiredprivate EmailPushChannelStrategy emailPushChannelStrategy;private static final Map<PushChannel,PushChannelStrategy> pushChannelBuilderMap=new HashMap<>();@PostConstructpublic void init(){pushChannelBuilderMap.put(PushChannel.SMS,smsPushChannelStrategy);pushChannelBuilderMap.put(PushChannel.Email,emailPushChannelStrategy);pushChannelBuilderMap.put(PushChannel.DING_TALK,dingTalkPushChannelStrategy);}Public PushChannelStrategy getStrategy(PushChannel PushChannel){if(PushChannel==null){return null;}return pushChannelBuilderMap.get(PushChannel);}
}

用到的枚举类：

@Getter
public enum PushChannel{SMS(＂sms＂，＂短信＂），EMAIL(＂email＂，＂邮件＂），DING_TALK(＂dingTalk＂，＂钉钉＂）；private final String value;PushChannel(String value,String desc){this.value=value;}public static PushChannel getPushChannel(String pushChannel){if(pushChannel==null){return null;}for(PushChannel channel:PushChannel.values()){if(pushChannel.equals(channel.getValue())){return channel;}}return null;}
}

在使用的时候通过策略工厂里面的方法获取具体的策略类：

@Slf4j
@Servicepublic class MessagePushService{@Autowiredprivate PushChannelStrategyFactory pushChannelStrategyFactory;@Autowiredprivate MessageRecordRepository messageRecordRepository;public ResultDTO<Boolean> pushSync(MessagePushCommand command){MessagePushParam messagePushParam =MessagePushAssembler.convert(command);//1,业务逻辑处理//2、根据渠道进行触达PushChannel pushChannel=messagePushParam.getChannel();if(pushChannel==null){throw new MessagePushException(xxx);}//3、获取具体的策略类PushChannelStrategy pushChannelStrategy=pushChannelStrategyFactory.getStrategy(pushChannel);SendResult sendResult=PushChannelStrategy.send(messagePushParam,xxx);//4,记录落库return ResultDTO.getSuccessResult（true）;｝｝

到此该版本的策略模式+工厂模式就结束了，欢迎点评和指出不足之处。