ElasticSearch使用
Java API操作ES
相关依赖：
<dependencies>
<dependency>
<groupId>org.elasticsearch.clientgroupId>
<artifactId>elasticsearch-rest-high-level-clientartifactId>
<version>7.6.1version>
dependency>
<dependency>
<groupId>org.apache.logging.log4jgroupId>
<artifactId>log4j-coreartifactId>
<version>2.11.1version>
dependency>
<dependency>
<groupId>com.alibabagroupId>
<artifactId>fastjsonartifactId>
<version>1.2.62version>
dependency>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.12version>
<scope>testscope>
dependency>
<dependency>
<groupId>org.testnggroupId>
<artifactId>testngartifactId>
<version>6.14.3version>
<scope>testscope>
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ID
jobDetail.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GetRequest
GetRequest 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API
SearchRequest 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SearchSourceBuilder
MultiMatchQueryBuilder 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ID
jobDetail.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API
SearchRequest 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SearchSourceBuilder
MultiMatchQueryBuilder 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ID
jobDetail.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API
SearchRequest 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SearchSourceBuilder
MultiMatchQueryBuilder 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ID
jobDetail.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
- 配置高亮选项
// 设置高亮
HighlightBuilder highlightBuilder = new HighlightBuilder();
highlightBuilder.field("title");
highlightBuilder.field("jd");
highlightBuilder.preTags("");
highlightBuilder.postTags("");
- 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.bootgroupId>
<artifactId>spring-boot-starter-data-elasticsearchartifactId>
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
*/
@Test
public void test1(){
Book book = new Book(1,"三国演义","罗贯中");
bookRepository.index(book);
}
/**
* 根据书名查询
*/
@Test
public void test2(){
List<Book> list = bookRepository.findBookByName("演义");
for (Book book:list) {
System.out.println(book);
}
}