目录：

1.概述

2.JedisAdapter

3.EventModel

4.EventHandler

5.LikeHandler

6.EventProducer

7.EventConsumer

1.概述

在一个网站中，一个业务发生的同时，还有一些后续业务需要发生。

比如点赞，除了完成点赞功能外，还有一系列，比如提醒被点赞的用户等等，为了能够实现这些操作并且不拖慢单纯点赞功能的实现，我们将这些使用异步队列实现。

处理流程如下图：

Biz为业务部门，理解为点赞的实现，也就是在实现点赞的同时通过EventProducer发送一个事件；

这个事件进入队列等待，队列另一头，有一个EventConsumer，不断消费事件；

EventConsumer下面有很多EventHandler，只要EventHandler发现自己需要处理的事件类型，就会进行相应的操作。

优点：①后续业务的实现，不会拖慢主业务。②如果后续业务的服务器挂掉，只要重启，继续从优先队列消费事件即可。

2.JedisAdapter

在jedisAdapter中添加如下方法

public void setObject(String key, Object obj) {//将一个对象转换为一个jsoon串存入set中set(key, JSON.toJSONString(obj));
}public <T> T getObject(String key, Class<T> clazz) {//从set中取出json串，并转换为相应objectString value = get(key);if (value != null) {return JSON.parseObject(value, clazz);}return null;
}

3.EventModel

即发送的队列的事件模型，只有一些基本属性和get、set方法。

其中一些set的return 设置为this，是因为方便连续set多个属性。

package com.nowcoder.async;import java.awt.*;
import java.util.HashMap;
import java.util.Map;/*** Created by nowcoder on 2016/7/14.*/
public class EventModel {private EventType type;private int actorId;private int entityId;private int entityType;private int entityOwnerId;private Map<String, String> exts = new HashMap<>();public Map<String, String> getExts() {return exts;}public EventModel() {}public EventModel(EventType type) {this.type = type;}public String getExt(String name) {return exts.get(name);}public EventModel setExt(String name, String value) {exts.put(name, value);return this;}public EventType getType() {return type;}public EventModel setType(EventType type) {this.type = type;return this;}public int getActorId() {return actorId;}public EventModel setActorId(int actorId) {this.actorId = actorId;return this;}public int getEntityId() {return entityId;}public EventModel setEntityId(int entityId) {this.entityId = entityId;return this;}public int getEntityType() {return entityType;}public EventModel setEntityType(int entityType) {this.entityType = entityType;return this;}public int getEntityOwnerId() {return entityOwnerId;}public EventModel setEntityOwnerId(int entityOwnerId) {this.entityOwnerId = entityOwnerId;return this;}
}

EventType

package com.nowcoder.async;/*** Created by nowcoder on 2016/7/14.*/
public enum EventType {//枚举类LIKE(0),COMMENT(1),LOGIN(2),MAIL(3);private int value;EventType(int value) {this.value = value;}public int getValue() {return value;}
}

4.EventHandler

设计为一个接口，handler都实现此接口。

package com.nowcoder.async;import java.util.List;/*** Created by nowcoder on 2016/7/14.*/
public interface EventHandler {void doHandle(EventModel model);//处理此事件List<EventType> getSupportEventTypes();//添加监视的事件类型
}

5.LikeHandler

实现EventHandler接口。

package com.nowcoder.async.handler;import com.nowcoder.async.EventHandler;
import com.nowcoder.async.EventModel;
import com.nowcoder.async.EventType;
import com.nowcoder.model.Message;
import com.nowcoder.model.User;
import com.nowcoder.service.MessageService;
import com.nowcoder.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;import java.util.Arrays;
import java.util.Date;
import java.util.List;/*** Created by nowcoder on 2016/7/14.*/
@Component
public class LikeHandler implements EventHandler {@AutowiredMessageService messageService;@AutowiredUserService userService;@Overridepublic void doHandle(EventModel model) {Message message = new Message();User user = userService.getUser(model.getActorId());message.setToId(model.getEntityOwnerId());message.setContent("用户" + user.getName() +" 赞了你的资讯,http://127.0.0.1:8080/news/"+ String.valueOf(model.getEntityId()));// SYSTEM ACCOUNTmessage.setFromId(3);message.setCreatedDate(new Date());messageService.addMessage(message);}@Overridepublic List<EventType> getSupportEventTypes() {//只关注“like”类型的事件return Arrays.asList(EventType.LIKE);}
}

6.EventProducer

负责将事件添加到队列中。

package com.nowcoder.async;import com.alibaba.fastjson.JSONObject;
import com.nowcoder.util.JedisAdapter;
import com.nowcoder.util.RedisKeyUtil;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.ExceptionHandler;/*** Created by nowcoder on 2016/7/14.*/
@Service
public class EventProducer {@AutowiredJedisAdapter jedisAdapter;public boolean fireEvent(EventModel eventModel) {try {String json = JSONObject.toJSONString(eventModel);//生成valueString key = RedisKeyUtil.getEventQueueKey();//生成keyjedisAdapter.lpush(key, json);//将事件添加到队列中return true;} catch (Exception e) {return false;}}
}

7.EventConsumer

负责从队列中消费事件。

package com.nowcoder.async;import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.nowcoder.async.handler.LoginExceptionHandler;
import com.nowcoder.util.JedisAdapter;
import com.nowcoder.util.RedisKeyUtil;
import org.apache.commons.collections.MapUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Service;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;/*** Created by nowcoder on 2016/7/14.*/
@Service
public class EventConsumer implements InitializingBean, ApplicationContextAware {//InitializingBean  通过实现此接口的afterPropertiesSet()方法记录哪些Event需要哪些handler来处理
//ApplicationContextAware  通过实现此接口的setApplicationContext方法获取上下文private static final Logger logger = LoggerFactory.getLogger(EventConsumer.class);//用来存储一个事件类型对应的所有的eventhandler，下次有该事件产生时，即可直接调用对应的listprivate Map<EventType, List<EventHandler>> config = new HashMap<>();private ApplicationContext applicationContext;@Autowiredprivate JedisAdapter jedisAdapter;@Overridepublic void afterPropertiesSet() throws Exception {//记录哪些Event需要哪些handler来处理//找出上下文中所有实现了EventHandler接口的类，存入beansMap<String, EventHandler> beans = applicationContext.getBeansOfType(EventHandler.class);if (beans != null) {//遍历所有的handler，将他们存入他们所监听的eventType对应的list中for (Map.Entry<String, EventHandler> entry : beans.entrySet()) {List<EventType> eventTypes = entry.getValue().getSupportEventTypes();//查看事件的监视事件for (EventType type : eventTypes) {if (!config.containsKey(type)) {config.put(type, new ArrayList<EventHandler>());}// 注册每个事件的处理函数config.get(type).add(entry.getValue());}}}// 启动线程去消费事件Thread thread = new Thread(new Runnable() {@Overridepublic void run() {// 从队列一直消费while (true) {String key = RedisKeyUtil.getEventQueueKey();List<String> messages = jedisAdapter.brpop(0, key);//从redis的队列中取出事件，并存入list中// 第一个元素是队列名字，跳过for (String message : messages) {if (message.equals(key)) {continue;}EventModel eventModel = JSON.parseObject(message, EventModel.class);// 找到这个事件的处理handler列表if (!config.containsKey(eventModel.getType())) {logger.error("不能识别的事件");continue;}for (EventHandler handler : config.get(eventModel.getType())) {//处理他的所有的handlerhandler.doHandle(eventModel);}}}}});thread.start();}@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {this.applicationContext = applicationContext;}
}