1、Elasticsearch简介

  • 一个分布式的、Restful风格的搜索引擎。
  • 支持对各种类型的数据的检索。
  • 搜索速度快，可以提供实时的搜索服务。
  • 便于水平扩展，每秒可以处理PB级海量数据。

• Elasticsearch术语

  • 索引、类型、文档、字段。

  • 集群、节点、分片、副本。

    2、下载安装、配置与简单应用

    下载链接：https://www.elastic.co/cn/downloads/past-releases/elasticsearch-6-4-3
    1、下载完后直接解压
    2、修改配置
    cluster.name:nowcoder
    path.data: d:/AAcommunity\data\elasticsearch6.4.3\data
    path.logs: d:/AAcommunity\data\elasticsearch6.4.3\logs
    3、配置bin目录的环境变量
    4、下载中文分词插件
    (1)github搜索elasticsearch ik
    (2)将中文分词插件解压到elasticsearch安装目录下的plugins的新建目录ik下
    5、下载postman
    6、启动elasticsearch-》双击elasticseaarch.bat文件或执行命令elasticsearch.bat
    7、查看健康状态命令：curl -X GET “localhost:9200/_cat/health?v
    8、查看有什么节点：curl -X GET “localhost:9200/_cat/nodes?v”
    9、查看有什么索引：curl -X GET “localhost:9200/_cat/indices？v”
    10、创建索引：curl -X PUT “localhost:9200/test”
    11、删除索引：curl -X DELETE “localhost:9200/test”
    案例：
    PUT
    localhost:9200/test/_doc/1 “title”:”互联网求职” “content”:”寻求一份运营的岗位”
    localhost:9200/test/_doc/2 “title”:”互联网招聘” “content”:”招聘一名资深程序员”
    localhost:9200/test/_doc/3 “title”:”实习生推荐” “content”:”本人在一家互联网公司任职，可推荐实习开发岗位”
    GET
    localhost：9200/test/_search?q=title:互联网
    localhost：9200/test/_search?q=content:运营实习
    两者都检索的情况：localhost：9200/test/_search
    {
    “query”:{
    “multi_match”:{
    “query”:”互联网”
    “fields”:[“title”,”content”]
    }
    }
    }

    3、elasticsearch整合springboot

    1、导入依赖

    1. <dependency>
    2.   <groupId>org.springframework.boot</groupId>
    3.   <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
    4. </dependency>

    2、配置

    1. #配置ElasticsearchProperties
    2. spring.data.elasticsearch.cluster-name=nowcoder
    3. spring.data.elasticsearch.cluster-nodes=localhost:9300

    3、解决netty启动冲突问题
    CommunityApplication.java

    1. @PostConstruct
    2.   public void init(){
    3.       //解决netty启动冲突问题
    4.       System.setProperty("es.set.netty.runtime.available.processors","false");
    5.   }

    4、配置对应实体类
    DiscussPost.java

    1. @Data
    2. @AllArgsConstructor
    3. @NoArgsConstructor
    4. @ToString
    5. //版本：_doc 分片：6 副本：3
    6. @Document(indexName = "dicusspost",type="_doc",shards=6,replicas = 3)
    7. public class DiscussPost {
    9.   @Id
    10.   private int id;
    11.   @Field(type = FieldType.Integer)
    12.   private int userId;
    13.   @Field(type= FieldType.Text,analyzer = "ik_max_word",searchAnalyzer = "ik_smart")
    14.   private String title;
    15.   @Field(type= FieldType.Text,analyzer = "ik_max_word",searchAnalyzer = "ik_smart")
    16.   private String content;
    17.   @Field(type = FieldType.Integer)
    18.   private int type;//0普通1置顶
    19.   @Field(type = FieldType.Integer)
    20.   private int status;//0正常1精华2拉黑
    21.   @Field(type = FieldType.Date)
    22.   private Date createTime;
    23.   @Field(type = FieldType.Integer)
    24.   private int commentCount;
    25.   @Field(type = FieldType.Double)
    26.   private double score;
    27. }

    5、创建DiscussPostRepository接口

    1. @Repository
    2. public interface DiscussPostRepository extends ElasticsearchRepository<DiscussPost,Integer> {
    3. }

    6、测试 ```java @Autowired private DiscussPostMapper discussMapper;

    @Autowired private DiscussPostRepository discussRepository;

    @Autowired private ElasticsearchTemplate elasticTemplate;

    @Test public void testInsert() {

    1.   discussRepository.save(discussMapper.selectDiscussPostById(241));
    2.   discussRepository.save(discussMapper.selectDiscussPostById(242));
    3.   discussRepository.save(discussMapper.selectDiscussPostById(243));

    }

    @Test public void testInsertList() {

    1.   discussRepository.saveAll(discussMapper.selectDiscussPosts(101, 0, 100));
    2.   discussRepository.saveAll(discussMapper.selectDiscussPosts(102, 0, 100));
    3.   discussRepository.saveAll(discussMapper.selectDiscussPosts(103, 0, 100));
    4.   discussRepository.saveAll(discussMapper.selectDiscussPosts(111, 0, 100));
    5.   discussRepository.saveAll(discussMapper.selectDiscussPosts(112, 0, 100));
    6.   discussRepository.saveAll(discussMapper.selectDiscussPosts(131, 0, 100));
    7.   discussRepository.saveAll(discussMapper.selectDiscussPosts(132, 0, 100));
    8.   discussRepository.saveAll(discussMapper.selectDiscussPosts(133, 0, 100));
    9.   discussRepository.saveAll(discussMapper.selectDiscussPosts(134, 0, 100));

    }

    @Test public void testUpdate() {

    1.   DiscussPost post = discussMapper.selectDiscussPostById(231);
    2.   post.setContent("我是新人,使劲灌水.");
    3.   discussRepository.save(post);

    }

    @Test public void testDelete() {

    1.   // discussRepository.deleteById(231);
    2.   discussRepository.deleteAll();

    }

    @Test public void testSearchByRepository() {

    1.   SearchQuery searchQuery = new NativeSearchQueryBuilder()
    2.           .withQuery(QueryBuilders.multiMatchQuery("互联网寒冬", "title", "content"))
    3.           .withSort(SortBuilders.fieldSort("type").order(SortOrder.DESC))
    4.           .withSort(SortBuilders.fieldSort("score").order(SortOrder.DESC))
    5.           .withSort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC))
    6.           .withPageable(PageRequest.of(0, 10))
    7.           .withHighlightFields(
    8.                   new HighlightBuilder.Field("title").preTags("<em>").postTags("</em>"),
    9.                   new HighlightBuilder.Field("content").preTags("<em>").postTags("</em>")
    10.           ).build();
    12.   // elasticTemplate.queryForPage(searchQuery, class, SearchResultMapper)
    13.   // 底层获取得到了高亮显示的值, 但是没有返回.
    15.   Page<DiscussPost> page = discussRepository.search(searchQuery);
    16.   System.out.println(page.getTotalElements());
    17.   System.out.println(page.getTotalPages());
    18.   System.out.println(page.getNumber());
    19.   System.out.println(page.getSize());
    20.   for (DiscussPost post : page) {
    21.       System.out.println(post);
    22.   }

    }

    @Test public void testSearchByTemplate() {

    1.   SearchQuery searchQuery = new NativeSearchQueryBuilder()
    2.           .withQuery(QueryBuilders.multiMatchQuery("互联网寒冬", "title", "content"))
    3.           .withSort(SortBuilders.fieldSort("type").order(SortOrder.DESC))
    4.           .withSort(SortBuilders.fieldSort("score").order(SortOrder.DESC))
    5.           .withSort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC))
    6.           .withPageable(PageRequest.of(0, 10))
    7.           .withHighlightFields(
    8.                   new HighlightBuilder.Field("title").preTags("<em>").postTags("</em>"),
    9.                   new HighlightBuilder.Field("content").preTags("<em>").postTags("</em>")
    10.           ).build();
    12.   Page<DiscussPost> page = elasticTemplate.queryForPage(searchQuery, DiscussPost.class, new SearchResultMapper() {
    13.       @Override
    14.       public <T> AggregatedPage<T> mapResults(SearchResponse response, Class<T> aClass, Pageable pageable) {
    15.           SearchHits hits = response.getHits();
    16.           if (hits.getTotalHits() <= 0) {
    17.               return null;
    18.           }
    20.           List<DiscussPost> list = new ArrayList<>();
    21.           for (SearchHit hit : hits) {
    22.               DiscussPost post = new DiscussPost();
    24.               String id = hit.getSourceAsMap().get("id").toString();
    25.               post.setId(Integer.valueOf(id));
    27.               String userId = hit.getSourceAsMap().get("userId").toString();
    28.               post.setUserId(Integer.valueOf(userId));
    30.               String title = hit.getSourceAsMap().get("title").toString();
    31.               post.setTitle(title);
    33.               String content = hit.getSourceAsMap().get("content").toString();
    34.               post.setContent(content);
    36.               String status = hit.getSourceAsMap().get("status").toString();
    37.               post.setStatus(Integer.valueOf(status));
    39.               String createTime = hit.getSourceAsMap().get("createTime").toString();
    40.               post.setCreateTime(new Date(Long.valueOf(createTime)));
    42.               String commentCount = hit.getSourceAsMap().get("commentCount").toString();
    43.               post.setCommentCount(Integer.valueOf(commentCount));
    45.               // 处理高亮显示的结果
    46.               HighlightField titleField = hit.getHighlightFields().get("title");
    47.               if (titleField != null) {
    48.                   post.setTitle(titleField.getFragments()[0].toString());
    49.               }
    51.               HighlightField contentField = hit.getHighlightFields().get("content");
    52.               if (contentField != null) {
    53.                   post.setContent(contentField.getFragments()[0].toString());
    54.               }
    56.               list.add(post);
    57.           }
    59.           return new AggregatedPageImpl(list, pageable,
    60.                   hits.getTotalHits(), response.getAggregations(), response.getScrollId(), hits.getMaxScore());
    61.       }
    62.   });
    64.   System.out.println(page.getTotalElements());
    65.   System.out.println(page.getTotalPages());
    66.   System.out.println(page.getNumber());
    67.   System.out.println(page.getSize());
    68.   for (DiscussPost post : page) {
    69.       System.out.println(post);
    70.   }

    }

  1. <a name="Uvbhn"></a>
  2. # 4、开发搜索功能
  3. 1、ElasticsearchService.java
  4. ```java
  5. @Service
  6. public class ElasticsearchService {
  8.     @Autowired
  9.     private DiscussPostRepository discussPostRepository;
  10.     @Autowired
  11.     private ElasticsearchTemplate elasticTemplate;
  13.     /**
  14.      * 存储帖子
  15.      * @param post
  16.      */
  17.     public void savePost(DiscussPost post){
  18.          discussPostRepository.save(post);
  19.     }
  21.     /**
  22.      * 删除帖子
  23.      * @param id
  24.      */
  25.     public void deletePost(int id){
  26.         discussPostRepository.deleteById(id);
  27.     }
  29.     /**
  30.      * 搜索帖子
  31.      * @param keyword
  32.      * @param current
  33.      * @param limit
  34.      * @return
  35.      */
  36.     public Page<DiscussPost> search(String keyword,int current,int limit){
  37.         SearchQuery searchQuery = new NativeSearchQueryBuilder()
  38.                 .withQuery(QueryBuilders.multiMatchQuery(keyword, "title", "content"))
  39.                 .withSort(SortBuilders.fieldSort("type").order(SortOrder.DESC))
  40.                 .withSort(SortBuilders.fieldSort("score").order(SortOrder.DESC))
  41.                 .withSort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC))
  42.                 .withPageable(PageRequest.of(current, limit))
  43.                 .withHighlightFields(
  44.                         new HighlightBuilder.Field("title").preTags("<em>").postTags("</em>"),
  45.                         new HighlightBuilder.Field("content").preTags("<em>").postTags("</em>")
  46.                 ).build();
  48.         return elasticTemplate.queryForPage(searchQuery, DiscussPost.class, new SearchResultMapper() {
  49.             @Override
  50.             public <T> AggregatedPage<T> mapResults(SearchResponse response, Class<T> aClass, Pageable pageable) {
  51.                 SearchHits hits = response.getHits();
  52.                 if (hits.getTotalHits() <= 0) {
  53.                     return null;
  54.                 }
  56.                 List<DiscussPost> list = new ArrayList<>();
  57.                 for (SearchHit hit : hits) {
  58.                     DiscussPost post = new DiscussPost();
  60.                     String id = hit.getSourceAsMap().get("id").toString();
  61.                     post.setId(Integer.valueOf(id));
  63.                     String userId = hit.getSourceAsMap().get("userId").toString();
  64.                     post.setUserId(Integer.valueOf(userId));
  66.                     String title = hit.getSourceAsMap().get("title").toString();
  67.                     post.setTitle(title);
  69.                     String content = hit.getSourceAsMap().get("content").toString();
  70.                     post.setContent(content);
  72.                     String status = hit.getSourceAsMap().get("status").toString();
  73.                     post.setStatus(Integer.valueOf(status));
  75.                     String createTime = hit.getSourceAsMap().get("createTime").toString();
  76.                     post.setCreateTime(new Date(Long.valueOf(createTime)));
  78.                     String commentCount = hit.getSourceAsMap().get("commentCount").toString();
  79.                     post.setCommentCount(Integer.valueOf(commentCount));
  81.                     // 处理高亮显示的结果
  82.                     HighlightField titleField = hit.getHighlightFields().get("title");
  83.                     if (titleField != null) {
  84.                         post.setTitle(titleField.getFragments()[0].toString());
  85.                     }
  87.                     HighlightField contentField = hit.getHighlightFields().get("content");
  88.                     if (contentField != null) {
  89.                         post.setContent(contentField.getFragments()[0].toString());
  90.                     }
  92.                     list.add(post);
  93.                 }
  95.                 return new AggregatedPageImpl(list, pageable,
  96.                         hits.getTotalHits(), response.getAggregations(), response.getScrollId(), hits.getMaxScore());
  97.             }
  98.         });
  99.     }
  100. }

2、CommunityConstant

  1.   /**
  2.      * 发帖
  3.      */
  4.     String TOPIC_PUBLISH="publish";

3、DiscussPostController.java
在发布帖子接口中添加

  1.          // 触发发帖事件
  2.         Event event = new Event()
  3.                 .setTopic(TOPIC_PUBLISH)
  4.                 .setUserId(user.getId())
  5.                 .setEntityType(ENTITY_TYPE_POST)
  6.                 .setEntityId(post.getId());
  7.         eventProducer.fireEvent(event);

4、CommentController

  1. if(comment.getEntityType()==ENTITY_TYPE_POST){
  2.             // 触发发帖事件
  3.             event = new Event()
  4.                     .setTopic(TOPIC_PUBLISH)
  5.                     .setUserId(comment.getId())
  6.                     .setEntityType(ENTITY_TYPE_POST)
  7.                     .setEntityId(discussPostId);
  8.             eventProducer.fireEvent(event);
  9. }

5、EventConsumer.java

  1. // 消费发帖事件
  2.     @KafkaListener(topics = {TOPIC_PUBLISH})
  3.     public void handlePublishMessage(ConsumerRecord record) {
  4.         if (record == null || record.value() == null) {
  5.             logger.error("消息的内容为空!");
  6.             return;
  7.         }
  9.         Event event = JSONObject.parseObject(record.value().toString(), Event.class);
  10.         if (event == null) {
  11.             logger.error("消息格式错误!");
  12.             return;
  13.         }
  15.         DiscussPost post = discussPostService.findDiscussPostById(event.getEntityId());
  16.         elasticsearchService.saveDiscussPost(post);
  17.     }

6、SearchController

  1. @Controller
  2. public class SearchController implements CommunityConstant {
  4.     @Autowired
  5.     private ElasticsearchService elasticsearchService;
  7.     @Autowired
  8.     private UserService userService;
  10.     @Autowired
  11.     private LikeService likeService;
  13.     // search?keyword=xxx
  14.     @RequestMapping(path = "/search", method = RequestMethod.GET)
  15.     public String search(String keyword, Page page, Model model) {
  16.         // 搜索帖子
  17.         org.springframework.data.domain.Page<DiscussPost> searchResult =
  18.                 elasticsearchService.searchDiscussPost(keyword, page.getCurrent() - 1, page.getLimit());
  19.         // 聚合数据
  20.         List<Map<String, Object>> discussPosts = new ArrayList<>();
  21.         if (searchResult != null) {
  22.             for (DiscussPost post : searchResult) {
  23.                 Map<String, Object> map = new HashMap<>();
  24.                 // 帖子
  25.                 map.put("post", post);
  26.                 // 作者
  27.                 map.put("user", userService.selectUserById(post.getUserId()));
  28.                 // 点赞数量
  29.                 map.put("likeCount", likeService.findEntityLikeCount(ENTITY_TYPE_POST, post.getId()));
  31.                 discussPosts.add(map);
  32.             }
  33.         }
  34.         model.addAttribute("discussPosts", discussPosts);
  35.         model.addAttribute("keyword", keyword);
  37.         // 分页信息
  38.         page.setPath("/search?keyword=" + keyword);
  39.         page.setRows(searchResult == null ? 0 : (int) searchResult.getTotalElements());
  41.         return "/site/search";
  42.     }
  43. }

7、页面（略）
index.html===>处理搜索框
search.html