Springboot 集成EventBus

Guava的事件总线EventBus库是事件发布订阅模式的实现，让我们能在领域驱动设计(DDD)中以事件的弱引用本质对我们的模块和领域边界很好的解耦设计。下面是常用的异步事件的例子：

1、先初始化一个AsyncEventBus

import com.google.common.eventbus.AsyncEventBus;
import com.google.common.eventbus.EventBus;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.util.concurrent.Executors;

@Configuration
public class EventBusConfig {

//  @Bean
//  public EventBus eventBus(){
//      return new EventBus();
//  }

    @Bean
    public AsyncEventBus asyncEventBus(){
        return new AsyncEventBus(Executors.newFixedThreadPool(10));
    }

}

注：AsyncEventBus是异步的，EventBus不是

2、事件发布

import com.google.common.eventbus.AsyncEventBus;
import com.google.common.eventbus.EventBus;
import com.xxx.vo.ExpBucketUserVo;
import com.xxx.vo.ExperimentBucketUserCountVo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

@Slf4j
@Service
public class EventHandler {

//  @Autowired
//  private EventBus eventBus;

    @Autowired
    private AsyncEventBus asyncEventBus;

    @Autowired
    private EventListener eventListener;

//  @PostConstruct
//  public void init() {
//      eventBus.register(eventListener);
//  }
//
//  @PreDestroy
//  public void destroy() {
//      eventBus.unregister(eventListener);
//  }

    @PostConstruct
    public void init() {
        asyncEventBus.register(eventListener);
    }

    @PreDestroy
    public void destroy() {
        asyncEventBus.unregister(eventListener);
    }

    public void eventPost(ExpBucketUserVo expBucketUserVo){
//      eventBus.post(expBucketUserVo);
        asyncEventBus.post(expBucketUserVo);
        log.info("eventBus post event {}",expBucketUserVo);
    }

    public void eventPost(ExperimentBucketUserCountVo experimentBucketUserCountVo){
//      eventBus.post(experimentBucketUserCountVo);
        asyncEventBus.post(experimentBucketUserCountVo);
        log.info("eventBus post event {}",experimentBucketUserCountVo);
    }

}

3、事件订阅

import com.google.common.eventbus.Subscribe;
import com.xxx.persistence.dao.AbExpBucketUserCountMapper;
import com.xxx.persistence.dao.AbExpBucketUserMapper;
import com.xxx.persistence.entity.ExperimentBucketUser;
import com.xxx.persistence.entity.ExperimentBucketUserCount;
import com.xxx.service.convert.ExpBucketUserCountResponseConverter;
import com.xxx.service.convert.ExpBucketUserResponseConverter;
import com.xxx.vo.ExpBucketUserVo;
import com.xxx.vo.ExperimentBucketUserCountVo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Slf4j
@Service
public class EventListener {
    @Autowired
    private AbExpBucketUserMapper abExpBucketUserMapper;

    @Autowired
    private AbExpBucketUserCountMapper abExpBucketUserCountMapper;

    @Subscribe
    public void onMessageEvent(ExpBucketUserVo expBucketUserVo) {
        try {
            //CommonResponse response = expBucketUserService.insert(expBucketUserVo);
            ExperimentBucketUser experimentBucketUser = ExpBucketUserResponseConverter.INSTANCE.convertFrom(expBucketUserVo);
            Integer i = abExpBucketUserMapper.insert(experimentBucketUser);
            log.info("sync insert into ExperimentBucketUser,param={},result={}",expBucketUserVo,i);
        }catch (Exception e){
            log.error("sync insert into ExperimentBucketUser error,param={},error={}",expBucketUserVo,e);
        }
    }



    @Subscribe
    public void onMessageEvent(ExperimentBucketUserCountVo expBucketUserCountVo) {
        try {
            //CommonResponse response = expBucketUserCountService.incrementCountBy(experimentBucketUserCountVo);
            Integer i=  abExpBucketUserCountMapper.incrementCountBy(expBucketUserCountVo.getExperimentId(),expBucketUserCountVo.getBucketId());
            if(i<1){
                //说明没有初始化
                ExperimentBucketUserCount expBucketUserCount = ExpBucketUserCountResponseConverter.INSTANCE
                        .convertFrom(expBucketUserCountVo);
                i= abExpBucketUserCountMapper.insert(expBucketUserCount);
            }

            log.info("sync insert into ExperimentBucketUserCount,param={},result={}",expBucketUserCountVo,i);
        }catch (Exception e){
            log.error("sync insert into ExperimentBucketUserCountCount error,param={},error={}",expBucketUserCountVo,e);
        }
    }
}

4、使用

    @Autowired
    private EventHandler eventHandler;

     //异步
     eventHandler.eventPost(expBucketUserVo);