快速入门
使用RestClient客户端进行数据搜索可以分为两步
- 构建并发起请求
代码解读：
- 第一步，创建
SearchRequest对象，指定索引库名 - 第二步，利用
request.source()构建DSL，DSL中可以包含查询、分页、排序、高亮等
-
query()：代表查询条件，利用QueryBuilders.matchAllQuery()构建一个match_all查询的DSL
- 第三步，利用
client.search()发送请求，得到响应
核心步骤:
- 这里关键的API有两个，一个是
request.source()，它构建的就是DSL中的完整JSON参数。其中包含了query、sort、from、size、highlight等所有功能：
- 另一个是
QueryBuilders，其中包含了我们学习过的各种叶子查询、复合查询等：
- 解析查询结果
elasticsearch返回的结果是一个JSON字符串，结构包含：
hits：命中的结果
-
total：总条数，其中的value是具体的总条数值max_score：所有结果中得分最高的文档的相关性算分hits：搜索结果的文档数组，其中的每个文档都是一个json对象
-
-
_source：文档中的原始数据，也是json对象
-
因此，我们解析响应结果，就是逐层解析JSON字符串，流程如下：
SearchHits：通过response.getHits()获取，就是JSON中的最外层的hits，代表命中的结果
-
SearchHits#getTotalHits().value：获取总条数信息SearchHits#getHits()：获取SearchHit数组，也就是文档数组
-
-
SearchHit#getSourceAsString()：获取文档结果中的_source，也就是原始的json文档数据
-
示例
- 新建测试类
public class ElasticSearchTest {private RestHighLevelClient client;@Testvoid test() {System.out.println("client =" + client);}@BeforeEachvoid setup() {client = new RestHighLevelClient(RestClient.builder(HttpHost.create("http://192.168.1.97:9200")));}@AfterEachvoid tearDown() throws IOException {if (client != null) {client.close();}}
}
- 创建并发送请求, 解析结果
public class ElasticSearchTest {private RestHighLevelClient client;@Testvoid test() {System.out.println("client =" + client);}@Testvoid testMatchAll() throws IOException {//1.创建request对象SearchRequest request = new SearchRequest("items");//2.配置request参数request.source().query(QueryBuilders.matchAllQuery());//3.发送请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);System.out.println("response = " + response);//4.解析结果SearchHits searchHits = response.getHits();// 总条数long total = searchHits.getTotalHits().value;System.out.println("total = " + total);// 命中的数据SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {// 获取source结果String json = hit.getSourceAsString();// 转为ItemDocItemDoc doc = JSONUtil.toBean(json, ItemDoc.class);System.out.println("doc = " + doc);}}@BeforeEachvoid setup() {client = new RestHighLevelClient(RestClient.builder(HttpHost.create("http://192.168.1.97:9200")));}@AfterEachvoid tearDown() throws IOException {if (client != null) {client.close();}}
}
- 执行结果
构建查询条件
全文检索的查询条件构造API如下
精确查询的查询条件构造API如下:
布尔查询的查询条件构造API如下:
构建复杂查询条件的搜索
需求: 利用lavaRestClient实现搜索功能, 条件如下
- 搜索关键字为脱脂牛奶
- 品牌必须为德亚
- 价格必须低于300
public class ElasticSearchTest {private RestHighLevelClient client;@Testvoid test() {System.out.println("client =" + client);}@Testvoid testSearch() throws IOException {//1.创建request对象SearchRequest request = new SearchRequest("items");//2.组织DSL参数request.source().query(QueryBuilders.boolQuery().must(QueryBuilders.matchQuery("name", "脱脂牛奶")).filter(QueryBuilders.termQuery("brand", "德亚")).filter(QueryBuilders.rangeQuery("price").lt(3000)));//3.发送请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);System.out.println("response = " + response);//4.解析结果parseResponseResult(response);}private void parseResponseResult(SearchResponse response) {//4.解析结果SearchHits searchHits = response.getHits();// 总条数long total = searchHits.getTotalHits().value;System.out.println("total = " + total);// 命中的数据SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {// 获取source结果String json = hit.getSourceAsString();// 转为ItemDocItemDoc doc = JSONUtil.toBean(json, ItemDoc.class);System.out.println("doc = " + doc);}}@BeforeEachvoid setup() {client = new RestHighLevelClient(RestClient.builder(HttpHost.create("http://192.168.1.97:9200")));}@AfterEachvoid tearDown() throws IOException {if (client != null) {client.close();}}
}
排序和分页
与query类似，排序和分页参数都是基于request.source()来设置:
public class ElasticSearchTest {private RestHighLevelClient client;@Testvoid test() {System.out.println("client =" + client);}@Testvoid testSortAndPage() throws IOException {// 模拟前端分页参数int pageNo = 1, pageSize = 5;//1.创建request对象SearchRequest request = new SearchRequest("items");//2.组织DSL条件//2.1query条件request.source().query(QueryBuilders.matchAllQuery());//2.2.分页条件request.source().from((pageNo - 1) * pageSize).size(pageSize);//2.3 排序条件request.source().sort("sold", SortOrder.DESC).sort("price",SortOrder.ASC);//3.发送请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);//4.解析结果parseResponseResult(response);}private void parseResponseResult(SearchResponse response) {//4.解析结果SearchHits searchHits = response.getHits();// 总条数long total = searchHits.getTotalHits().value;System.out.println("total = " + total);// 命中的数据SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {// 获取source结果String json = hit.getSourceAsString();// 转为ItemDocItemDoc doc = JSONUtil.toBean(json, ItemDoc.class);System.out.println("doc = " + doc);}}@BeforeEachvoid setup() {client = new RestHighLevelClient(RestClient.builder(HttpHost.create("http://192.168.1.97:9200")));}@AfterEachvoid tearDown() throws IOException {if (client != null) {client.close();}}
}
高亮展示
高亮显示的条件构造API如下
高亮显示的结果解析API如下:
示例
public class ElasticSearchTest {private RestHighLevelClient client;@Testvoid test() {System.out.println("client =" + client);}@Testvoid testHighLight() throws IOException {//1.创建request对象SearchRequest request = new SearchRequest("items");//2.组织DSL条件//2.1query条件request.source().query(QueryBuilders.matchQuery("name", "脱脂牛奶"));//2.2.高亮条件request.source().highlighter(SearchSourceBuilder.highlight().field("name"));//3.发送请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);//4.解析结果parseResponseResult(response);}private void parseResponseResult(SearchResponse response) {//4.解析结果SearchHits searchHits = response.getHits();// 总条数long total = searchHits.getTotalHits().value;System.out.println("total = " + total);// 命中的数据SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {// 获取source结果String json = hit.getSourceAsString();// 转为ItemDocItemDoc doc = JSONUtil.toBean(json, ItemDoc.class);// 按需处理高亮结果Map<String, HighlightField> hfs = hit.getHighlightFields();if (hfs != null && !hfs.isEmpty()) {// 根据高亮字段名获取高亮结果HighlightField hf = hfs.get("name");// 获取高亮结果, 覆盖非高亮结果String name = hf.fragments()[0].string();doc.setName(name);}System.out.println("doc = " + doc);}}@BeforeEachvoid setup() {client = new RestHighLevelClient(RestClient.builder(HttpHost.create("http://192.168.1.97:9200")));}@AfterEachvoid tearDown() throws IOException {if (client != null) {client.close();}}
}
