问答社区-系统通知(kafka)
1.发送系统通知
需求
触发事件：
- 评论后，发布通知
- 点赞后，发布通知
- 关注后，发布通知
处理事件：
- 封装事件对象
- 开发事件的生产者
- 开发事件的消费者
1、新建事件对象
set的时候返回当前对象，这样就可以一直set了
/**
* 事件
*/
public class Event {
//事件主题
private String topic;
//事件触发的人
private int userId;
//目标实体
private int entityType;
private int entityId;
private int entityUserId;
private Map<String, Object> data = new HashMap<>();
public String getTopic() {
return topic;
}
public Event setTopic(String topic) {
this.topic = topic;
return this;
}
public int getUserId() {
return userId;
}
public Event setUserId(int userId) {
this.userId = userId;
return this;
}
public int getEntityType() {
return entityType;
}
public Event setEntityType(int entityType) {
this.entityType = entityType;
return this;
}
public int getEntityId() {
return entityId;
}
public Event setEntityId(int entityId) {
this.entityId = entityId;
return this;
}
public int getEntityUserId() {
return entityUserId;
}
public Event setEntityUserId(int entityUserId) {
this.entityUserId = entityUserId;
return this;
}
public Map<String, Object> getData() {
return data;
}
public Event setData(String key,Object value) {
this.data.put(key,value);
return this;
}
}2、新建事件生产者
使用kafkatemplate，将对应的事件发布到指定的topic
@Component
public class EventProducer {
@Autowired
private KafkaTemplate kafkaTemplate;
//处理事件
public void fireEvent(Event event){
//将事件发布到指定的主题
kafkaTemplate.send(event.getTopic(), JSONObject.toJSONString(event));
}
}3、新建事件消费者
每当事件发生，将对应的数据新增到message表中
@Component
public class EventConsumer implements CommunityConstant {
private static final Logger logger = LoggerFactory.getLogger(EventConsumer.class);
@Autowired
private MessageService messageService;
@KafkaListener(topics = {TOPIC_COMMENT, TOPIC_LIKE, TOPIC_FOLLOW})
public void handleCommentMessage(ConsumerRecord record) {
if (record == null || record.value() == null) {
logger.error("消息的内容为空");
return;
}
Event event = JSONObject.parseObject(record.value().toString(), Event.class);
if (event == null) {
logger.error("消息格式错误");
return;
}
//发送站内通知
Message message = new Message();
message.setFromId(SYSTEM_USER_ID);
message.setToId(event.getEntityUserId());
message.setConversationId(event.getTopic());
message.setCreateTime(new Date());
Map<String, Object> content = new HashMap<>();
content.put("userId", event.getUserId());
content.put("entityType", event.getEntityType());
content.put("entityId", event.getEntityId());
if (!event.getData().isEmpty()) {
for (Map.Entry<String, Object> entry : event.getData().entrySet()) {
content.put(entry.getKey(), entry.getValue());
}
}
message.setContent(JSONObject.toJSONString(content));
messageService.addMessage(message);
}
}4、找到评论、点赞、关注的controller，新增事件触发
CommentController
@RequestMapping(value = "/add/{discussPostId}", method = RequestMethod.POST)
public String addComment(@PathVariable("discussPostId") int discussPostId, Comment comment) {
comment.setUserId(hostHolder.getUser().getId());
comment.setStatus(0);
comment.setCreateTime(new Date());
commentService.addComment(comment);
//触发评论事件
Event event = new Event().setTopic(TOPIC_COMMENT).
setUserId(hostHolder.getUser().getId()).
setEntityType(comment.getEntityType()).
setEntityId(comment.getEntityId()).
setData("postId", discussPostId);
if (comment.getEntityType() == ENTITY_TYPE_POST) {
int userId = discussPostService.findDiscussPostById(comment.getEntityId()).getUserId();
event.setEntityUserId(userId);
}else if(comment.getEntityType() == ENTITY_TYPE_COMMENT){
Comment target = commentService.findCommentById(comment.getEntityId());
event.setEntityUserId(target.getUserId());
}
eventProducer.fireEvent(event);
return "redirect:/discuss/detail/" + discussPostId;
}likeController
@RequestMapping(value = "/like", method = RequestMethod.POST)
@ResponseBody
public String like(int entityType, int entityId,int entityUserId,int postId) {
User user = hostHolder.getUser();
//点赞
likeService.like(user.getId(), entityType, entityId,entityUserId);
//数量
long entityLikeCount = likeService.findEntityLikeCount(entityType, entityId);
//状态
int entityLikeStatus = user == null ? 0 : likeService.findEntityLikeStatus(user.getId(), entityType, entityId);
Map<String, Object> map = new HashMap<>();
map.put("likeCount", entityLikeCount);
map.put("likeStatus", entityLikeStatus);
if(entityLikeStatus == 1){
Event event = new Event().setTopic(TOPIC_LIKE)
.setUserId(hostHolder.getUser().getId())
.setEntityType(entityType)
.setEntityId(entityId)
.setEntityUserId(entityUserId)
.setData("postId",postId);
eventProducer.fireEvent(event);
}
return CommunityUtil.getJSONString(0, null, map);
}followController
@LoginRequired
@RequestMapping(value = "/follow", method = RequestMethod.POST)
@ResponseBody
public String follow(int entityType, int entityId) {
User user = hostHolder.getUser();
followService.follow(user.getId(), entityType, entityId);
//触发事件
Event event = new Event().setTopic(TOPIC_FOLLOW)
.setUserId(user.getId())
.setEntityType(entityType)
.setEntityId(entityId)
.setEntityUserId(entityId);
eventProducer.fireEvent(event);
return CommunityUtil.getJSONString(0, "已关注！");
}2.显示系统通知
需求：
通知列表
- 显示评论、点赞、关注三种类型的通知
通知详情 - 分页显示某一主题所包含的通知
未读消息 - 在页面头部显示所有的未读消息数量
1.开发持久层
这里面会显示评论、点赞、关注的通知
根据需求，需要新增加三个查询
1）查询未读消息数量
2）查询最新一条消息
3）查询其中某个主题的通知数量
4)查询某个主题包含的通知列表
这里贴上代码，要注意的是：
查询未读消息数量有两种，一种是某个主题的未读消息，另一种是整个通知的未读消息数量
这里就可以加一个<if>动态判断参数的传递，做到复用</if>
<select id="selectLatestNotice" resultType="Message">
select <include refid="selectFields"></include>
from message
where id in (
select max(id) from message
where status != 2
and from_id = 1
and to_id = #{userId}
and conversation_id = #{topic}
)
</select>
<select id="selectNoticeCount" resultType="int">
SELECT count(id)
FROM message
WHERE status != 2
AND from_id = 1
AND to_id = #{userId}
AND conversation_id = #{topic}
</select>
<select id="selectNoticeUnreadCount" resultType="int">
select count(id)
from message
where status = 0
and from_id = 1
and to_id = #{userId}
<if test="topic!=null"> //这里判断有没有传过来确切主题
and conversation_id=#{topic}
</if>
</select>
<select id="selectNotices" resultType="Message">
select <include refid="selectFields"></include>
from message
where status != 2
and from_id = 1
and to_id = #{userId}
and conversation_id = #{topic}
order by create_time desc
LIMIT #{offset},#{limit}
</select>2.服务层
这一层主要是调用持久层的方法，执行SQL语句，就不贴了
3.开发控制层
当点击通知按钮，调用messageService中的查询方法，将最新一条的数据查询出来，并把相关信息传递到前台页面
//通知
@RequestMapping(path = "/notice/list", method = RequestMethod.GET)
public String getNoticeList(Model model) {
User user = hostHolder.getUser();
// 查询评论类通知
Message message = messageService.findLatestNotice(user.getId(), TOPIC_COMMENT);
if (message != null) {
Map<String, Object> messageVO = new HashMap<>();
messageVO.put("message", message);
String content = HtmlUtils.htmlUnescape(message.getContent());
Map<String, Object> data = JSONObject.parseObject(content, HashMap.class);
messageVO.put("user", userService.findUserById((Integer) data.get("userId")));
messageVO.put("entityType", data.get("entityType"));
messageVO.put("entityId", data.get("entityId"));
messageVO.put("postId", data.get("postId"));
int count = messageService.findNoticeCount(user.getId(), TOPIC_COMMENT);
messageVO.put("count", count);
int unread = messageService.findNoticeUnreadCount(user.getId(), TOPIC_COMMENT);
messageVO.put("unread", unread);
model.addAttribute("commentNotice", messageVO);
}
// 查询未读消息数量
int letterUnreadCount = messageService.findLetterUnreadCount(user.getId(), null);
model.addAttribute("letterUnreadCount", letterUnreadCount);
int noticeUnreadCount = messageService.findNoticeUnreadCount(user.getId(), null);
model.addAttribute("noticeUnreadCount", noticeUnreadCount);
return "/site/notice";
}通知列表页面
将查询到的帖子List中的每一个通知实体放到一个大的集合中去
其中通知实体以及其中包含的内容（一个小通知）放到一个map中
将每一个小通知放到List集合中返回给主页面
@RequestMapping(path = "/notice/detail/{topic}", method = RequestMethod.GET)
public String getNoticeDetail(@PathVariable("topic") String topic, Page page, Model model) {
User user = hostHolder.getUser();
page.setLimit(5);
page.setRows(messageService.findNoticeCount(user.getId(), topic));
page.setPath("/notice/detail/" + topic);
List<Message> noticeList = messageService.findNotices(user.getId(), topic, page.getOffset(), page.getLimit());
List<Map<String, Object>> noticeVoList = new ArrayList<>();
if (noticeList != null) {
Map<String, Object> map = new HashMap<>();
for (Message notice : noticeList) {
//通知
map.put("notice", notice);
//内容
String content = HtmlUtils.htmlUnescape(notice.getContent());
Map<String, Object> data = JSONObject.parseObject(content, HashMap.class);
map.put("user", userService.findUserById((Integer) data.get("userId")));
map.put("entityType", data.get("entityType"));
map.put("entityId", data.get("entityId"));
map.put("postId", data.get("postId"));
//通知作者
map.put("fromUser", userService.findUserById(notice.getFromId()));
noticeVoList.add(map);
}
}
model.addAttribute("notices", noticeVoList);
List<Integer> ids = getLetterIds(noticeList);
if (!ids.isEmpty()) {
messageService.readMessage(ids);
}
return "/site/notice-detail";
}
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