ElasticSearch使用RestHighLevelClient进行搜索查询

Elasticsearch Java API有四类client连接方式：TransportClient、 RestClient 、Jest、 Spring_Data_Elasticsearch。其中TransportClient、 RestClient是Elasticsearch原生的api，TransportClient会在8.0版本中完成删除，替代的是HighLevelRestClient，它使用HTTP请求而不是Java序列化请求。Spring_Data_Elasticsearch是spring集成的Elasticsearch开发包。在博客园 Elasticsearch 6.4基本操作 – Java版一文中有简单的描述，不再过多引述。本文主要记录一下HighLevelRestClient在spingboot项目中的使用。

使用es主要是做一些非关系型数据文档的检索，公司用的最多的是配合kibana进行可视化的日志检索，非常方便。elasticsearch、kibana安装，配置和使用，有大量博客记录，此处不再说明。

@Configuration配置sping并启动容器 @Bean注册Bean

import org.apache.http.HttpHost;
import org.apache.http.client.config.RequestConfig.Builder;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestClientBuilder.HttpClientConfigCallback;
import org.elasticsearch.client.RestClientBuilder.RequestConfigCallback;
import org.elasticsearch.client.RestHighLevelClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.ArrayList;@Configuration
public class ESConfig {    private static String hosts = "127.0.0.1"; // 集群地址，多个用,隔开
    private static int port = 9200; // 使用的端口号
    private static String schema = "http"; // 使用的协议
    private static ArrayList<HttpHost> hostList = null;    private static int connectTimeOut = 1000; // 连接超时时间
    private static int socketTimeOut = 30000; // 连接超时时间
    private static int connectionRequestTimeOut = 500; // 获取连接的超时时间    private static int maxConnectNum = 100; // 最大连接数
    private static int maxConnectPerRoute = 100; // 最大路由连接数
    static {
        hostList = new ArrayList<>();
        String[] hostStrs = hosts.split(",");
        for (String host : hostStrs) {
            hostList.add(new HttpHost(host, port, schema));
        }
    }
    @Bean
    public RestHighLevelClient client(){
        RestClientBuilder builder = RestClient.builder(hostList.toArray(new HttpHost[0]));
        // 异步httpclient连接延时配置
        builder.setRequestConfigCallback(new RequestConfigCallback() {
            @Override
            public Builder customizeRequestConfig(Builder requestConfigBuilder) {
                requestConfigBuilder.setConnectTimeout(connectTimeOut);
                requestConfigBuilder.setSocketTimeout(socketTimeOut);
                requestConfigBuilder.setConnectionRequestTimeout(connectionRequestTimeOut);
                return requestConfigBuilder;
            }
        });
        // 异步httpclient连接数配置
        builder.setHttpClientConfigCallback(new HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                httpClientBuilder.setMaxConnTotal(maxConnectNum);
                httpClientBuilder.setMaxConnPerRoute(maxConnectPerRoute);
                return httpClientBuilder;
            }
        });
        RestHighLevelClient client = new RestHighLevelClient(builder);
        return client;
    }
}

写一个service。

import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.MatchQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.index.query.RangeQueryBuilder;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.io.IOException;
import java.util.Arrays;@Service
public class ElasticSearchService {
    private static final Logger log = LoggerFactory.getLogger(ElasticSearchService.class);    @Autowired
    private RestHighLevelClient client;    public String search() throws IOException {
        BoolQueryBuilder boolBuilder = QueryBuilders.boolQuery();
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        MatchQueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("fields.entity_id", "319");//这里可以根据字段进行搜索，must表示符合条件的，相反的mustnot表示不符合条件的
       // RangeQueryBuilder rangeQueryBuilder = QueryBuilders.rangeQuery("fields_timestamp"); //新建range条件
       // rangeQueryBuilder.gte("2019-03-21T08:24:37.873Z"); //开始时间
       // rangeQueryBuilder.lte("2019-03-21T08:24:37.873Z"); //结束时间
       // boolBuilder.must(rangeQueryBuilder);
        boolBuilder.must(matchQueryBuilder);
        sourceBuilder.query(boolBuilder); //设置查询，可以是任何类型的QueryBuilder。
        sourceBuilder.from(0); //设置确定结果要从哪个索引开始搜索的from选项，默认为0
        sourceBuilder.size(100); //设置确定搜素命中返回数的size选项，默认为10
　　　　  sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS)); //设置一个可选的超时，控制允许搜索的时间。        sourceBuilder.fetchSource(new String[] {"fields.port","fields.entity_id","fields.message"}, new String[] {}); //第一个是获取字段，第二个是过滤的字段，默认获取全部
        SearchRequest searchRequest = new SearchRequest("customer"); //索引
        searchRequest.types("doc"); //类型
        searchRequest.source(sourceBuilder);
        SearchResponse response = client.search(searchRequest, RequestOptions.DEFAULT);
        SearchHits hits = response.getHits();  //SearchHits提供有关所有匹配的全局信息，例如总命中数或最高分数：
        SearchHit[] searchHits = hits.getHits();
        for (SearchHit hit : searchHits) {
            log.info("search -> {}",hit.getSourceAsString());
        }
        return Arrays.toString(searchHits);
    }
}

上面的ElasticSearchService 有几个常用的Builder类和方法需要了解下。

BoolQueryBuilder用来拼装查询条件。一般来说must的性能要低一些，因为他要进行打分评估，也就是说要进行_score，而filter则不会。

filter(QueryBuilder queryBuilder)

Adds a query that must appear in the matching documents but will not contribute to scoring. must(QueryBuilder queryBuilder)

Adds a query that must appear in the matching documents and will contribute to scoring. should(QueryBuilder queryBuilder)

Adds a query that should appear in the matching documents. 简单来说：must 相当于与 & = ；must not 相当于非 ~ ！=；should 相当于或 | or ；filter 过滤

//filter 效率比 must高的多
 if (StringUtils.isNotBlank(query.getRouterDatabaseNo())) {
　　　boolQueryBuilder.filter(QueryBuilders.termQuery("routerDatabaseNo", query.getRouterDatabaseNo()));
 }//时间段 一定要有头有尾 不然会出现慢查询
 if (null != query.getCreateTime() && null != query.getUpdateTime()) {
     boolQueryBuilder.filter(QueryBuilders.rangeQuery("createTime").from( query.getCreateTime()).to(query.getUpdateTime()));
 }

SearchSourceBuilder

 SearchRequest searchRequest = new SearchRequest("customer"); //将请求限制为一个索引
 SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
 searchRequest.types("doc"); //将请求限制为一个类型。
 searchRequest.source(sourceBuilder); //将SearchSourceBuilder添加到SeachRequest

创建SeachRequest，没有参数，这将针对所有索引运行。有参数，则按参数所传值为索引，此处“customer”为索引值。大多数搜索参数都添加到SearchSourceBuilder中，它为搜索请求body中的所有内容提供了setter。

SearchSourceBuilder的排序：允许添加一个或多个SortBuilder实例，有四种特殊的实现（Field-，Score-，GeoDistance-和ScriptSortBuilder）。

sourceBuilder.sort(new ScoreSortBuilder().order(SortOrder.DESC)); //按_score降序排序（默认值）。
sourceBuilder.sort(new FieldSortBuilder("_uid").order(SortOrder.ASC));//也可以按_id字段进行升序排序

SearchSourceBuilder的源过滤：默认情况下，搜索请求会返回文档_source的内容，但与Rest API中的内容一样，你可以覆盖此行为，例如，你可以完全关闭_source检索：

sourceBuilder.fetchSource(false);

该方法还接受一个或多个通配符模式的数组，以控制以更精细的方式包含或排除哪些字段：

String[] includeFields = new String[] {"title", "user", "innerObject.*"};
String[] excludeFields = new String[] {"_type"};
sourceBuilder.fetchSource(includeFields, excludeFields);

SearchSourceBuilder的请求结果高亮显示：通过在SearchSourceBuilder上设置HighlightBuilder，可以实现高亮搜索结果，通过将一个或多个HighlightBuilder.Field实例添加到HighlightBuilder，可以为每个字段定义不同的高亮行为。

SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
HighlightBuilder highlightBuilder = new HighlightBuilder(); //创建一个新的HighlightBuilder。
HighlightBuilder.Field highlightTitle = new HighlightBuilder.Field("title");  //为title字段创建字段高光色。
highlightTitle.highlighterType("unified"); // 设置字段高光色类型。
highlightBuilder.field(highlightTitle);   //将字段高光色添加到高亮构建器。
HighlightBuilder.Field highlightUser = new HighlightBuilder.Field("user");
highlightBuilder.field(highlightUser);
searchSourceBuilder.highlighter(highlightBuilder);

SearchSourceBuilder 更多api可以参考链接文章，归纳的很详细了，不再过多引述。

写一个controller用于测试

import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.slowcity.admin.service.ElasticSearchService;@RestController
@RequestMapping("/test")
public class TestResource {    @Autowired
    private ElasticSearchService elasticSearchService;
    private static final Logger log = LoggerFactory.getLogger(TestResource.class);
    //条件 查询
    @PostMapping("/v1/test")
    public String query( ) {
        String queryResult =null;
        try {
            queryResult = elasticSearchService.search();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return queryResult;
    }
}

首先在es中维护几条数据，如下：

postman测试一下，结果如下：

【end】

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