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｛    @Autowired    private NoticeClient noticeClient；        @Override    public SendResult send（MessagePushParam param，BaseMsg baseMsg）｛        //1、before send check        //2、send sms        NoticeResult noticeResult=noticeClient.sendSms（xxxx）；        sendResult.setMessageStatus（MessageStatusEnum.SUCCESS）；        return sendResult；    ｝ ｝

邮件：

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

钉钉：

@Slf4j @Component public class DingTalkPushChannelStrategy implements PushChannelStrategy｛    @Autowired    private DingTalkClient dingTalkClient；        @Override    public SendResult send（MessagePushParam param，BaseMsg baseMsg）｛        //1、before send check        //2、send ding talk        SendResult 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；     @Autowired     private SmsPushChannelStrategy smsPushChannelStrategy；     @Autowired     private 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｛     @Autowired     private DingTalkPushChannelStrategy dingTalkPushChannelStrategy;     @Autowired     private SmsPushChannelStrategy smsPushChannelStrategy;     @Autowired     private EmailPushChannelStrategy emailPushChannelStrategy;          private static final Map pushChannelBuilderMap=new HashMap<>();          @PostConstruct     public 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 @Service  public class MessagePushService{      @Autowired      private PushChannelStrategyFactory pushChannelStrategyFactory;      @Autowired      private MessageRecordRepository messageRecordRepository;            public ResultDTO 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。