Elasticsearch Java HighLevel REST Client（Search API）

 Elasticsearch7.4 使用 RestHighLevelClient 简单教程

第一步：引入maven jar包      

 
            com.alibaba
            fastjson
            1.2.60
   
 

    org.elasticsearch.client
    elasticsearch-rest-high-level-client
    7.4.0
    
    
        
            org.elasticsearch
            elasticsearch
        
        
            org.elasticsearch.client
            elasticsearch-rest-client
        
    


    org.elasticsearch.client
    elasticsearch-rest-client
    7.4.0


    org.elasticsearch
    elasticsearch
    7.4.0

测试代码：

import com.alibaba.fastjson.JSON;
import org.apache.http.HttpHost;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.action.search.ClearScrollRequest;
import org.elasticsearch.action.search.ClearScrollResponse;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.search.SearchScrollRequest;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.client.core.CountRequest;
import org.elasticsearch.client.core.CountResponse;
import org.elasticsearch.client.indices.GetIndexRequest;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.MatchAllQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.Scroll;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * @description:
 * @author: z
 * @createDate: 2020/3/2 1:19 PM
 * @Version: 1.0
 */
public class EsTest {
    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

    public  static List getHostList(){
        List hostList = new ArrayList<>();
        String[] hostStrs = hosts.split(",");
        for (String host : hostStrs) {
            hostList.add(new HttpHost(host, port, schema));
        }
        return hostList;
    }

    public static RestHighLevelClient getClient(){

       RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(getHostList().toArray(new HttpHost[0])));
        return client;
    }

    public static void main(String[] args) throws InterruptedException, IOException {
        try(RestHighLevelClient client = getClient()) {
            //判断 是否存在 索引
           // boolean exists = client.indices().exists(new GetIndexRequest("student"), RequestOptions.DEFAULT);
          //  System.out.println(exists);

           // GetRequest request = new GetRequest("student","1000");
           // GetResponse response = client.get(request, RequestOptions.DEFAULT);
             //System.out.println("getById:"+response.getSource());

            //Student 属性 id，name，gender 等
            //Student user = JSON.parseObject(new String(response.getSourceAsBytes()), Student.class);
            //System.out.println(user.getId());

            SearchRequest searchRequest = new SearchRequest("student");

            // 这个可以理解  (name = '张三' or name = '李四') and gender='man'
            BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery()
                   // .must(QueryBuilders.termQuery("id", "10000")) id =10000
                    // matchQuery 联想模糊，类似百度搜索框，matchPhraseQuery 类似与sql like 模糊查询
                    .must(QueryBuilders.boolQuery().should(QueryBuilders.matchPhraseQuery("name", "张三"))
                            .should(QueryBuilders.matchPhraseQuery("name", "李四")))
                    .must(QueryBuilders.matchPhraseQuery("gender", "man"))
                    ;
            //  searchSourceBuilder.fetchSource(new String[]{"id","ts"}, null);//查询字段
            // searchSourceBuilder.size(2);//返回记录数
            searchRequest.source(new SearchSourceBuilder().query(boolQueryBuilder));

            SearchResponse searchResponse =  client.search(searchRequest, RequestOptions.DEFAULT);
            SearchHits hits = searchResponse.getHits();
            System.out.println("total:"+hits.getTotalHits());

            SearchHit[] searchHits = hits.getHits();
            System.out.println("size:"+searchHits.length);

            for(SearchHit hit : searchHits) {
                System.out.println("json data:"+hit.getSourceAsString());
                System.out.println("id:"+hit.getSourceAsMap().get("ts").toString());
               // System.out.println("---"+hit.getSourceAsString());
            }

            //滚动查询
            scroll(client);

        }catch (Exception e){
            e.printStackTrace();
        }
    }

    /**
     * 获取总记录数
     * @param client
     * @return
     * @throws IOException
     */
    public static long getTotal(RestHighLevelClient client) throws IOException {
        SearchRequest searchRequest = new SearchRequest("student");
        MatchAllQueryBuilder matchAllQueryBuilder =  QueryBuilders.matchAllQuery();

        SearchSourceBuilder searchSourceBuilder =  new SearchSourceBuilder();
        searchSourceBuilder.query(matchAllQueryBuilder);
        searchRequest.source(searchSourceBuilder);

        CountRequest countRequest = new CountRequest("student");
        // System.out.println(countRequest.source().toString());
        CountResponse response = client.count(countRequest, RequestOptions.DEFAULT);
        System.out.println("total:"+response.getCount());
        //打印查询语句字符串
        System.out.println(searchSourceBuilder.toString());
        return response.getCount();
    }

    /**
     * scroll 滚动查询
     * @param client
     */
    public static void scroll(RestHighLevelClient client) throws IOException {
        //初始化scroll
        final Scroll scroll = new Scroll(TimeValue.timeValueMinutes(1L)); //设定滚动时间间隔
        SearchRequest searchRequest = new SearchRequest("student");
        searchRequest.scroll(scroll);

        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //这里查询所有，可以  QueryBuilders.boolQuery() QueryBuilders 设置查询条件，
        searchSourceBuilder.query(QueryBuilders.matchAllQuery());
        searchSourceBuilder.size(2); //设定每次返回多少条数据
        searchRequest.source(searchSourceBuilder);

        System.out.println(searchSourceBuilder.toString());
        SearchResponse searchResponse = null;
        searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
        
        String scrollId = searchResponse.getScrollId();
        System.out.println(searchResponse.getHits().getTotalHits());
        SearchHit[] searchHits = searchResponse.getHits().getHits();
        System.out.println("----第一页-----》");
        for (SearchHit searchHit : searchHits) {
            System.out.println(searchHit.getSourceAsString());
        }
        //遍历符合搜索条件的数据，直到没有数据
        while (searchHits != null && searchHits.length > 0) {
            SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId);
            scrollRequest.scroll(scroll);

            searchResponse = client.scroll(scrollRequest, RequestOptions.DEFAULT);

            scrollId = searchResponse.getScrollId();
            searchHits = searchResponse.getHits().getHits();
            if (searchHits != null && searchHits.length > 0) {
                System.out.println("----下一页-----》");
                for (SearchHit searchHit : searchHits) {
                    System.out.println(searchHit.getSourceAsString());
                }
            }

        }
        //清除滚屏
        ClearScrollRequest clearScrollRequest = new ClearScrollRequest();
        //或者用setScrollIds()指定多个scrollId 
        clearScrollRequest.addScrollId(scrollId);
        ClearScrollResponse clearScrollResponse = null;

        clearScrollResponse = client.clearScroll(clearScrollRequest,RequestOptions.DEFAULT);
        boolean succeeded = clearScrollResponse.isSucceeded();
        System.out.println("succeeded:" + succeeded);
    }

}

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