Java API操作ES

相关依赖：

<dependencies><!-- ES的高阶的客户端API --><dependency><groupId>org.elasticsearch.client</groupId><artifactId>elasticsearch-rest-high-level-client</artifactId><version>7.6.1</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-core</artifactId><version>2.11.1</version></dependency><!-- 阿里巴巴出品的一款将Java对象转换为JSON、将JSON转换为Java对象的库 --><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.62</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope>
</dependency><dependency><groupId>org.testng</groupId><artifactId>testng</artifactId><version>6.14.3</version><scope>test</scope></dependency></dependencies>

使用JavaAPI来操作ES集群

初始化连接
使用的是RestHighLevelClient去连接ES集群，后续操作ES中的数据

  private RestHighLevelClient restHighLevelClient;public JobFullTextServiceImpl() {// 建立与ES的连接// 1. 使用RestHighLevelClient构建客户端连接。// 2. 基于RestClient.builder方法来构建RestClientBuilder// 3. 用HttpHost来添加ES的节点RestClientBuilder restClientBuilder = RestClient.builder(new HttpHost("192.168.21.130", 9200, "http"), new HttpHost("192.168.21.131", 9200, "http"), new HttpHost("192.168.21.132", 9200, "http"));restHighLevelClient = new RestHighLevelClient(restClientBuilder);}

添加职位数据到ES中

• 使用IndexRequest对象来描述请求
  • 可以设置请求的参数：设置ID、并设置传输ES的数据——注意因为ES都是使用JSON（DSL）来去操作数据的，所以需要使用一个FastJSON的库来将对象转换为JSON字符串进行操作

@Override
public void add(JobDetail jobDetail) throws IOException {//1.	构建IndexRequest对象，用来描述ES发起请求的数据。IndexRequest indexRequest = new IndexRequest(JOB_IDX);//2.	设置文档ID。indexRequest.id(jobDetail.getId() + "");//3.	使用FastJSON将实体类对象转换为JSON。String json = JSONObject.toJSONString(jobDetail);//4.	使用IndexRequest.source方法设置文档数据，并设置请求的数据为JSON格式。indexRequest.source(json, XContentType.JSON);//5.	使用ES High level client调用index方法发起请求，将一个文档添加到索引中。restHighLevelClient.index(indexRequest, RequestOptions.DEFAULT);
}

查询/删除/搜索/分页

* 新增：IndexRequest
* 更新：UpdateRequest
* 删除：DeleteRequest
* 根据ID获取：GetRequest
* 关键字检索：SearchRequest

@Override
public JobDetail findById(long id) throws IOException {// 1.	构建GetRequest请求。GetRequest getRequest = new GetRequest(JOB_IDX, id + "");// 2.	使用RestHighLevelClient.get发送GetRequest请求，并获取到ES服务器的响应。GetResponse getResponse = restHighLevelClient.get(getRequest, RequestOptions.DEFAULT);// 3.	将ES响应的数据转换为JSON字符串String json = getResponse.getSourceAsString();// 4.	并使用FastJSON将JSON字符串转换为JobDetail类对象JobDetail jobDetail = JSONObject.parseObject(json, JobDetail.class);// 5.	记得：单独设置IDjobDetail.setId(id);return jobDetail;
}

@Override
public void update(JobDetail jobDetail) throws IOException {// 1.	判断对应ID的文档是否存在// a)	构建GetRequestGetRequest getRequest = new GetRequest(JOB_IDX, jobDetail.getId() + "");// b)	执行client的exists方法，发起请求，判断是否存在boolean exists = restHighLevelClient.exists(getRequest, RequestOptions.DEFAULT);if(exists) {// 2.	构建UpdateRequest请求UpdateRequest updateRequest = new UpdateRequest(JOB_IDX, jobDetail.getId() + "");// 3.	设置UpdateRequest的文档，并配置为JSON格式updateRequest.doc(JSONObject.toJSONString(jobDetail), XContentType.JSON);// 4.	执行client发起update请求restHighLevelClient.update(updateRequest, RequestOptions.DEFAULT);}
}

@Override
public void deleteById(long id) throws IOException {// 1.	构建delete请求DeleteRequest deleteRequest = new DeleteRequest(JOB_IDX, id + "");// 2.	使用RestHighLevelClient执行delete请求restHighLevelClient.delete(deleteRequest, RequestOptions.DEFAULT);}

@Override
public List<JobDetail> searchByKeywords(String keywords) throws IOException {// 1.构建SearchRequest检索请求// 专门用来进行全文检索、关键字检索的APISearchRequest searchRequest = new SearchRequest(JOB_IDX);// 2.创建一个SearchSourceBuilder专门用于构建查询条件SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();// 3.使用QueryBuilders.multiMatchQuery构建一个查询条件（搜索title、jd），并配置到SearchSourceBuilderMultiMatchQueryBuilder multiMatchQueryBuilder = QueryBuilders.multiMatchQuery(keywords, "title", "jd");// 将查询条件设置到查询请求构建器中searchSourceBuilder.query(multiMatchQueryBuilder);// 4.调用SearchRequest.source将查询条件设置到检索请求searchRequest.source(searchSourceBuilder);// 5.执行RestHighLevelClient.search发起请求SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);SearchHit[] hitArray = searchResponse.getHits().getHits();// 6.遍历结果ArrayList<JobDetail> jobDetailArrayList = new ArrayList<>();for (SearchHit documentFields : hitArray) {// 1)获取命中的结果String json = documentFields.getSourceAsString();// 2)将JSON字符串转换为对象JobDetail jobDetail = JSONObject.parseObject(json, JobDetail.class);// 3)使用SearchHit.getId设置文档IDjobDetail.setId(Long.parseLong(documentFields.getId()));jobDetailArrayList.add(jobDetail);}return jobDetailArrayList;
}

@Override
public Map<String, Object> searchByPage(String keywords, int pageNum, int pageSize) throws IOException {// 1.构建SearchRequest检索请求// 专门用来进行全文检索、关键字检索的APISearchRequest searchRequest = new SearchRequest(JOB_IDX);// 2.创建一个SearchSourceBuilder专门用于构建查询条件SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();// 3.使用QueryBuilders.multiMatchQuery构建一个查询条件（搜索title、jd），并配置到SearchSourceBuilderMultiMatchQueryBuilder multiMatchQueryBuilder = QueryBuilders.multiMatchQuery(keywords, "title", "jd");// 将查询条件设置到查询请求构建器中searchSourceBuilder.query(multiMatchQueryBuilder);// 每页显示多少条searchSourceBuilder.size(pageSize);// 设置从第几条开始查询searchSourceBuilder.from((pageNum - 1) * pageSize);// 4.调用SearchRequest.source将查询条件设置到检索请求searchRequest.source(searchSourceBuilder);// 5.执行RestHighLevelClient.search发起请求SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);SearchHit[] hitArray = searchResponse.getHits().getHits();// 6.遍历结果ArrayList<JobDetail> jobDetailArrayList = new ArrayList<>();for (SearchHit documentFields : hitArray) {// 1)获取命中的结果String json = documentFields.getSourceAsString();// 2)将JSON字符串转换为对象JobDetail jobDetail = JSONObject.parseObject(json, JobDetail.class);// 3)使用SearchHit.getId设置文档IDjobDetail.setId(Long.parseLong(documentFields.getId()));jobDetailArrayList.add(jobDetail);}// 8.	将结果封装到Map结构中（带有分页信息）// a)	total -> 使用SearchHits.getTotalHits().value获取到所有的记录数// b)	content -> 当前分页中的数据long totalNum = searchResponse.getHits().getTotalHits().value;HashMap hashMap = new HashMap();hashMap.put("total", totalNum);hashMap.put("content", jobDetailArrayList);return hashMap;
}

使用scroll分页方式查询

• 第一次查询，不带scroll_id，所以要设置scroll超时时间
• 超时时间不要设置太短，否则会出现异常
• 第二次查询，SearchSrollRequest

@Override
public Map<String, Object> searchByScrollPage(String keywords, String scrollId, int pageSize) throws IOException {SearchResponse searchResponse = null;if(scrollId == null) {// 1.构建SearchRequest检索请求// 专门用来进行全文检索、关键字检索的APISearchRequest searchRequest = new SearchRequest(JOB_IDX);// 2.创建一个SearchSourceBuilder专门用于构建查询条件SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();// 3.使用QueryBuilders.multiMatchQuery构建一个查询条件（搜索title、jd），并配置到SearchSourceBuilderMultiMatchQueryBuilder multiMatchQueryBuilder = QueryBuilders.multiMatchQuery(keywords, "title", "jd");// 将查询条件设置到查询请求构建器中searchSourceBuilder.query(multiMatchQueryBuilder);// 每页显示多少条searchSourceBuilder.size(pageSize);// 4.调用SearchRequest.source将查询条件设置到检索请求searchRequest.source(searchSourceBuilder);//--------------------------// 设置scroll查询//--------------------------searchRequest.scroll(TimeValue.timeValueMinutes(5));// 5.执行RestHighLevelClient.search发起请求searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);}// 第二次查询的时候，直接通过scroll id查询数据else {SearchScrollRequest searchScrollRequest = new SearchScrollRequest(scrollId);searchScrollRequest.scroll(TimeValue.timeValueMinutes(5));// 使用RestHighLevelClient发送scroll请求searchResponse = restHighLevelClient.scroll(searchScrollRequest, RequestOptions.DEFAULT);}//--------------------------// 迭代ES响应的数据//--------------------------SearchHit[] hitArray = searchResponse.getHits().getHits();// 6.遍历结果ArrayList<JobDetail> jobDetailArrayList = new ArrayList<>();for (SearchHit documentFields : hitArray) {// 1)获取命中的结果String json = documentFields.getSourceAsString();// 2)将JSON字符串转换为对象JobDetail jobDetail = JSONObject.parseObject(json, JobDetail.class);// 3)使用SearchHit.getId设置文档IDjobDetail.setId(Long.parseLong(documentFields.getId()));jobDetailArrayList.add(jobDetail);}// 8.	将结果封装到Map结构中（带有分页信息）// a)	total -> 使用SearchHits.getTotalHits().value获取到所有的记录数// b)	content -> 当前分页中的数据long totalNum = searchResponse.getHits().getTotalHits().value;HashMap hashMap = new HashMap();hashMap.put("scroll_id", searchResponse.getScrollId());hashMap.put("content", jobDetailArrayList);return hashMap;
}

高亮查询

1. 配置高亮选项

// 设置高亮
HighlightBuilder highlightBuilder = new HighlightBuilder();
highlightBuilder.field("title");
highlightBuilder.field("jd");
highlightBuilder.preTags("<font color='red'>");
highlightBuilder.postTags("</font>");

2. 需要将高亮的字段拼接在一起，设置到实体类中

// 设置高亮的一些文本到实体类中
// 封装了高亮
Map<String, HighlightField> highlightFieldMap = documentFields.getHighlightFields();
HighlightField titleHL = highlightFieldMap.get("title");
HighlightField jdHL = highlightFieldMap.get("jd");if(titleHL != null) {// 获取指定字段的高亮片段Text[] fragments = titleHL.getFragments();// 将这些高亮片段拼接成一个完整的高亮字段StringBuilder builder = new StringBuilder();for(Text text : fragments) {builder.append(text);}// 设置到实体类中jobDetail.setTitle(builder.toString());
}if(jdHL != null) {// 获取指定字段的高亮片段Text[] fragments = jdHL.getFragments();// 将这些高亮片段拼接成一个完整的高亮字段StringBuilder builder = new StringBuilder();for(Text text : fragments) {builder.append(text);}// 设置到实体类中jobDetail.setJd(builder.toString());
}

ES与springboot相连

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

@Document(indexName = "dahaiwuliang",type="book")
public class Book {private Integer id;private String name;private String author;
...
}

public interface BookRepository extends ElasticsearchRepository<Book,Integer> {public List<Book> findBookByName(String name);
}

	/*** SpringData ES索引*/@Testpublic void test1(){Book book = new Book(1,"三国演义","罗贯中");bookRepository.index(book);}/*** 根据书名查询*/@Testpublic void test2(){List<Book> list = bookRepository.findBookByName("演义");for (Book book:list) {System.out.println(book);}}