Springboot整合Elasticsearch

Springboot使用ES的基操

一、使用NativeSearchQuery查詢：

以下代碼羅列了幾種使用方式，可以通過組合實現其他復雜查詢。

package com.chx.util;

import com.alibaba.fastjson.JSONObject;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.sort.SortBuilders;
import org.elasticsearch.search.sort.SortOrder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.elasticsearch.core.ElasticsearchOperations;
import org.springframework.data.elasticsearch.core.query.NativeSearchQuery;
import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
import java.util.ArrayList;
import java.util.List;

public class EsTest {
    @Autowired
    private ElasticsearchOperations elasticsearchOperations;

    public void test() {
        //設置查詢的表名
        NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder().withIndices("tableName");
        BoolQueryBuilder boolQuery = QueryBuilders.boolQuery();
        //filter相當於and，和must的主要區別在於不進行打分(_score)
        boolQuery.filter(QueryBuilders.boolQuery().filter(QueryBuilders.termQuery("columns", "QL")));
        boolQuery.filter(QueryBuilders.termQuery("column", "00"));
        //查詢時間區間的方式
        boolQuery.filter(QueryBuilders.rangeQuery("time")
                .from("2020-11-10")
                .to("2020-12-20"));
        BoolQueryBuilder boolQuery2 = QueryBuilders.boolQuery();
        //有時候會有需求，前端傳過來list進行查詢，所以要注意層級關系。用新的BoolQueryBuilder封裝條件，最后放到最外層里，這樣就組合成了where (xxx) and (xxx) or (xxx)這種形式
        String[] flags = new String[]{"1", "2", "3", "4"};
        for (String twoLabel : flags) {
            boolQuery2.should(QueryBuilders.termsQuery("twoLabel", twoLabel));
        }
        //要查詢出的列名，如果不設置則默認全部。
        String[] columns = new String[]{"column1", "column2", "column3"};
        //設置查詢層級關系。組合查詢條件
        boolQuery.filter(boolQuery2);
        queryBuilder.withQuery(boolQuery);
        queryBuilder.withFields(columns);
        //設置排序條件
        queryBuilder.withSort(SortBuilders.fieldSort("column_sort").order(SortOrder.ASC));
        NativeSearchQuery build = queryBuilder.build();
        //獲取查詢結果
        SearchHits resultEs = elasticsearchOperations.query(build, response -> {
            return response.getHits();
        });
        SearchHit[] hits = resultEs.getHits();
        List mktCustomStructList = new ArrayList<>();
        for (SearchHit hit : hits) {
            //查詢結果轉換
            String sourceAsString = JSONObject.parseObject(hit.getSourceAsString(), String.class);
            //如果要從hit里取，可以用hit.getSourceAsMap0.get("columns").toString()方法
        }
    }
}

二、ES條件查詢的條數。

public void testCount(){
        //設置查詢的表名
        NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder().withIndices("tableName");
        BoolQueryBuilder boolQuery = QueryBuilders.boolQuery();
        //filter相當於and
        boolQuery.filter(QueryBuilders.boolQuery().filter(QueryBuilders.termQuery("columns", "QL")));
        boolQuery.filter(QueryBuilders.termQuery("column", "00"));
        //要查詢出的列名，如果不設置則默認全部。
        String[] columns = new String[]{"column1", "column2", "column3"};
        //設置查詢層級關系。組合查詢條件
        queryBuilder.withQuery(boolQuery);
        queryBuilder.withFields(columns);
        //設置排序條件
        queryBuilder.withSort(SortBuilders.fieldSort("column_sort").order(SortOrder.ASC));
        NativeSearchQuery build = queryBuilder.build();
        long count = elasticsearchOperations.count(build);
        System.out.println(count);
    }

三、注意點：

1.我maven引入的es版本如下，三個包。如果不用count函數，elasticsearch-rest-high-level-client和elasticsearch不用引用。

　　　　<dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
            <version>7.8.0</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-high-level-client</artifactId>
            <version>7.8.0</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>7.8.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
        </dependency>

2.一定要注意引入的版本對安裝的ES客戶端否支持，盡量引入的包要高於安裝的ES版本。否則甚至會啟動報錯或執行錯誤(執行過程中報錯或執行結果不正確)。

3.如果發生了exception is java.lang.NoSuchFieldError:IGNORE_DEPECATIONS的小伙伴，引入上述中的elasticsearch包即可解決。