第6章 Elasticsearch，分布式搜索引擎【仿牛客网社区论坛项目】

前言
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项目总结
第6章 Elasticsearch，分布式搜索引擎
- 1.Elasticsearch入门
- 2.Spring整合Elasticsearch
- - DiscussPostRepository
  - DiscussPostController
  - EventConsumer
- 3.开发社区搜索功能
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前言

2023-4-30 20:42:51

以下内容源自【Java面试项目】
仅供学习交流使用

项目总结

第6章 Elasticsearch，分布式搜索引擎

1.Elasticsearch入门

2.Spring整合Elasticsearch

导入依赖

        <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-elasticsearch</artifactId></dependency>

DiscussPostRepository

package com.jsss.community.dao.elasticsearch;import com.jsss.community.entity.DiscussPost;
import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;
import org.springframework.stereotype.Repository;/*
ElasticsearchRepository<DiscussPost, Integer>
DiscussPost：接口要处理的实体类
Integer：实体类中的主键是什么类型
ElasticsearchRepository：父接口，其中已经事先定义好了对es服务器访问的增删改查各种方法。Spring会给它自动做一个实现，我们直接去调就可以了。*/
@Repository
public interface DiscussPostRepository extends ElasticsearchRepository<DiscussPost, Integer> {}

DiscussPostController

发帖|删帖的时候，放到kakfa中了

    @RequestMapping(path = "/add",method = RequestMethod.POST)@ResponseBodypublic String addDiscussPost(String title,String content){User user=hostHolder.getUser();if (user==null){return CommunityUtil.getJSONString(403,"你还没有登录");}DiscussPost post=new DiscussPost();post.setUserId(user.getId());post.setTitle(title);post.setContent(content);post.setCreateTime(new Date());discussPostService.addDiscussPost(post);//触发发帖实践Event event =new Event().setTopic(TOPIC_PUBLISH).setUserId(user.getId()).setEntityType(ENTITY_TYPE_POST).setEntityId(post.getId());eventProducer.fireEvent(event);String redisKey= RedisKeyUtil.getPostScoreKey();redisTemplate.opsForSet().add(redisKey,post.getId());//报错的情况，将来统一处理return CommunityUtil.getJSONString(0,"发布成功！");}// 删除@RequestMapping(path = "/delete", method = RequestMethod.POST)@ResponseBodypublic String setDelete(int id) {discussPostService.updateStatus(id, 2);// 触发删帖事件Event event = new Event().setTopic(TOPIC_DELETE).setUserId(hostHolder.getUser().getId()).setEntityType(ENTITY_TYPE_POST).setEntityId(id);eventProducer.fireEvent(event);return CommunityUtil.getJSONString(0);}

EventConsumer

    // 消费发帖事件@KafkaListener(topics = {TOPIC_PUBLISH})public void handlePublishMessage(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;}DiscussPost post = discussPostService.findDiscussPostById(event.getEntityId());elasticsearchService.saveDiscussPost(post);}// 消费删帖事件@KafkaListener(topics = {TOPIC_DELETE})public void handleDeleteMessage(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;}elasticsearchService.deleteDiscussPost(event.getEntityId());}

3.开发社区搜索功能

ElasticsearchService

    public List<DiscussPost> searchDiscussPost(String keyword, int current, int limit) throws IOException {SearchRequest searchRequest = new SearchRequest("discusspost");//discusspost是索引名，就是表名NativeSearchQueryBuilder nativeSearchQueryBuilder = new NativeSearchQueryBuilder();//高亮HighlightBuilder highlightBuilder = new HighlightBuilder();highlightBuilder.field("title");highlightBuilder.field("content");highlightBuilder.requireFieldMatch(false);highlightBuilder.preTags("<em>");highlightBuilder.postTags("</em>");//构建搜索条件SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder().query(QueryBuilders.multiMatchQuery(keyword, "title", "content")).sort(SortBuilders.fieldSort("type").order(SortOrder.DESC)).sort(SortBuilders.fieldSort("score").order(SortOrder.DESC)).sort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC)).from(current)// 指定从哪条开始查询.size(limit)// 需要查出的总记录条数.highlighter(highlightBuilder);//高亮searchRequest.source(searchSourceBuilder);//这有个异常SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);List<DiscussPost> list = new LinkedList<>();for (SearchHit hit : searchResponse.getHits().getHits()) {DiscussPost discussPost = JSONObject.parseObject(hit.getSourceAsString(), DiscussPost.class);// 处理高亮显示的结果HighlightField titleField = hit.getHighlightFields().get("title");if (titleField != null) {discussPost.setTitle(titleField.getFragments()[0].toString());}HighlightField contentField = hit.getHighlightFields().get("content");if (contentField != null) {discussPost.setContent(contentField.getFragments()[0].toString());}
//            System.out.println(discussPost);list.add(discussPost);}return list;}