1、pom依赖

        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
            <version>8.14.0</version>
        </dependency>
        <dependency>
            <groupId>co.elastic.clients</groupId>
            <artifactId>elasticsearch-java</artifactId>
            <version>8.14.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
            <version>2.9.0</version> <!-- 使用你所需的版本 -->
        </dependency>
        <dependency>
            <groupId>jakarta.json.bind</groupId>
            <artifactId>jakarta.json.bind-api</artifactId>
            <version>2.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.13.2</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish</groupId>
            <artifactId>jakarta.json</artifactId>
            <version>2.0.1</version>
        </dependency>

2、ES 8.1的相关接口 主要参考： Java封装Elasticsearch8常用接口方法（一）_elasticsearch8 java接口-CSDN博客

3、EsService 主要 增加knnSearch 和 混合检索 mixSearch

/**
     * KNN搜索
     *
     * @param indexName 索引名称
     * @param vector 向量数据
     * @param field KNN字段名
     * @return KnnSearchResponse
     * @throws Exception
     */
    public SearchResponse knnSearchTestTwo(String indexName, List<Float> vector, String field, List<String> list) throws Exception {
        ElasticsearchClient client = ESClientPool.getClient();

        KnnQuery knnQuery = KnnQuery.of(m -> m.field(field).queryVector(vector).numCandidates(100));

        SearchResponse<ObjectNode> response = client.search(s -> s
                        .index(indexName)
                        .query(knnQuery._toQuery())
                        .source(SourceConfig.of(sf -> sf.filter(f -> f.includes(list))))
                , ObjectNode.class);

        List<ObjectNode> result = new ArrayList<>();
        for (Hit<ObjectNode> hit : response.hits().hits()) {
            ObjectNode source = hit.source();
            source.put("score", hit.score());
            result.add(source);
        }
        log.info("SearchResponse: {}", JSON.toJSONString(result));

        ESClientPool.returnClient(client);

        return response;
    }


    /**
     * 混合查询测试
     *
     * @param indexName 索引名称
     * @param searchText 查询文本
     * @param vector 向量
     * @param knnField KNN字段名
     * @return SearchResponse
     * @throws Exception
     */
    public SearchResponse mixSearch(String indexName, String searchText, String searchField, List<Float> vector, String knnField, List<String> returnFields) throws Exception {
        ElasticsearchClient client = ESClientPool.getClient();

        MatchQuery searchTextQuery = new MatchQuery.Builder().field(searchField).query(searchText).build();

        KnnQuery knnQuery = new KnnQuery.Builder()
                .field(knnField)
                .queryVector(vector)
                .numCandidates(100)
                .build();

        // 创建must子句的bool查询，这里只有一个should子句
        BoolQuery boolQuery = new BoolQuery.Builder()
                .must(searchTextQuery._toQuery()) // 必须满足的文本匹配
                .should(knnQuery._toQuery()) // 可以满足的向量相似性
                .build();

        SearchResponse<ObjectNode> response = client.search(s -> s
                        .index(indexName)
                        .query(boolQuery._toQuery())
                        .source(SourceConfig.of(sf -> sf.filter(f -> f.includes(returnFields))))
                , ObjectNode.class);


        ESClientPool.returnClient(client);

        return response;
    }