• Java 操作RestHighLevelClient查询详解

    根据我之前文章对 ES命令的查询使用，测试索引的文档数据前面文章有提到的。下面我们就通过 RestHighLevelClient来进行查询。

    参考官方AP文档：https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.17/_search_apis.html

    一、高级查询Query DSL

    Elasticsearch高级查询Query DSL：https://blog.csdn.net/qq_42402854/article/details/125357445

    1、查询接口的步骤

    一个查询接口的基本步骤如下：

    1、创建 SearchRequest搜索请求
   创建 SearchRequest 搜索请求，如果不带参数，表示查询所有索引
2、创建 SearchSourceBuilder条件构造
   创建 SearchSourceBuilder条件构造，构建搜索的条件。
   添加大部分查询参数到 SearchSourceBuilder，还可以接收 QueryBuilders构建的查询参数。
3、将 SearchSourceBuilder 添加到 SearchRequest中
4、执行查询
5、解析查询结果

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    其中，第二步和第五步最为关键。

    下面直接上代码，语法使用就不解释了。

    2、查询所有match_all

    使用 match_all，默认只会返回 10条数据。

    2.1 全量查询

        @Test
    public void testMatchAll() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求
        SearchRequest searchRequest = new SearchRequest();
        searchRequest.indices("db_idx4");//指定要查询的索引

        //2.创建 SearchSourceBuilder条件构造。builder模式这里就先不简写了
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        MatchAllQueryBuilder matchAllQueryBuilder = QueryBuilders.matchAllQuery();
        searchSourceBuilder.query(matchAllQueryBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println(searchResponse);
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println(hits.getTotalHits());
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> System.out.println("文档原生信息：" + p.getSourceAsString()));
    }

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    在这里插入图片描述

    2.2 分页查询

    • size 关键字：指定查询结果中返回指定条数。 默认返回值10条。
    • from 关键字：用来指定起始返回位置，和size关键字连用可实现分页效果
       @Test
    public void testMatchAllPage() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求
        SearchRequest searchRequest = new SearchRequest();
        searchRequest.indices("db_idx4");//指定要查询的索引

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder()
                .query(QueryBuilders.matchAllQuery());
        //设置分页
        searchSourceBuilder.from(1);
        searchSourceBuilder.size(5);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> System.out.println("文档原生信息：" + p.getSourceAsString()));
    }

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    在这里插入图片描述

    3、数据排序

        @Test
    public void testSortByAge() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求
        SearchRequest searchRequest = new SearchRequest();
        searchRequest.indices("db_idx4");//指定要查询的索引

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder()
                .query(QueryBuilders.matchAllQuery());
        //年龄倒序
        searchSourceBuilder.sort("age", SortOrder.DESC);
        searchSourceBuilder.sort("id", SortOrder.DESC);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> System.out.println("文档原生信息：" + p.getSourceAsString()));
    }

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    在这里插入图片描述

    4、数据过滤

    数据过滤就是 返回我们指定的字段。

        @Test
    public void testSource() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求
        SearchRequest searchRequest = new SearchRequest();
        searchRequest.indices("db_idx4");//指定要查询的索引

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder()
                .query(QueryBuilders.matchAllQuery());
        //指定需要返回或者排除的字段
        String[] includes = {"id", "name"};
        String[] excludes = {};
        searchSourceBuilder.fetchSource(includes, excludes);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> System.out.println("文档原生信息：" + p.getSourceAsString()));
    }

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    在这里插入图片描述

    5、match 查找

    match在匹配时会对所查找的关键词进行分词，然后按分词匹配查找。

        @Test
    public void testMatch() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("db_idx4");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //match 查找
        MatchQueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("address", "王者打野");
        matchQueryBuilder.operator(Operator.OR);
        searchSourceBuilder.query(matchQueryBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> System.out.println("文档原生信息：" + p.getSourceAsString()));
    }

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    6、多字段查询multi_match

    multi_match 关键字：可以根据字段类型，决定是否使用分词查询，得分最高的在前面。

        @Test
    public void testMultiMatch() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("db_idx4");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //MultiMatch 查找
        MultiMatchQueryBuilder multiMatchQuery = QueryBuilders.multiMatchQuery("王者辅助","address", "desc");
        multiMatchQuery.operator(Operator.OR);
        searchSourceBuilder.query(multiMatchQuery);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> System.out.println("文档原生信息：" + p.getSourceAsString()));
    }

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    7、精确查询Term

            //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //Term 查找
        //TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("age", 23);
        TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("address.keyword", "三国演义小乔");
        searchSourceBuilder.query(termQueryBuilder);

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    8、范围查询range

            //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //Range 查找
        RangeQueryBuilder rangeQueryBuilder = QueryBuilders.rangeQuery("age");
        rangeQueryBuilder.gte(18);
        rangeQueryBuilder.lt(23);
        searchSourceBuilder.query(rangeQueryBuilder);

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    9、日期查询range

            //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("product");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //日期Range 查找
        RangeQueryBuilder rangeQueryBuilder = QueryBuilders.rangeQuery("date"); //date字段
        rangeQueryBuilder.lt("now‐2y");
        searchSourceBuilder.query(rangeQueryBuilder);

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    10、多个id查询

            //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //多个id 查找
        IdsQueryBuilder idsQueryBuilder = QueryBuilders.idsQuery();
        idsQueryBuilder.addIds("2", "5", "1111");
        searchSourceBuilder.query(idsQueryBuilder);

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    11、高亮查询

        @Test
    public void testHighlight() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("db_idx4");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //Term 查找
        TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("address", "王者");
        searchSourceBuilder.query(termQueryBuilder);
        //自定义高亮 查找
        HighlightBuilder highlightBuilder = new HighlightBuilder();
        highlightBuilder.preTags("");
        highlightBuilder.postTags("");
        highlightBuilder.field("address"); 
        highlightBuilder.requireFieldMatch(false); //多字段时，需要设置为false
        highlightBuilder.field("desc");
        searchSourceBuilder.highlighter(highlightBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        hits.forEach(p -> {
            System.out.println("文档原生信息：" + p.getSourceAsString());
            System.out.println("高亮信息：" + p.getHighlightFields());
        });
    }

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    在这里插入图片描述

    12、布尔查询Bool

            //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //Bool查找
        BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
        // and
		//boolQueryBuilder.must(QueryBuilders.rangeQuery("age").gte(20));
		//boolQueryBuilder.must(QueryBuilders.matchQuery("sex", "0"));

        // or
		boolQueryBuilder.should(QueryBuilders.rangeQuery("age").gte(20));
		boolQueryBuilder.should(QueryBuilders.matchQuery("sex", "0"));
        searchSourceBuilder.query(boolQueryBuilder);

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    13、模糊查询

    		//2.创建 SearchSourceBuilder条件构造。
		SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
		//Fuzzy 查找
		FuzzyQueryBuilder fuzzyQueryBuilder = QueryBuilders.fuzzyQuery("name", "张").fuzziness(Fuzziness.ONE);

		searchSourceBuilder.query(fuzzyQueryBuilder);

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    二、聚合操作

    ElasticSearch聚合操作：https://blog.csdn.net/qq_42402854/article/details/125377293

    1、Metric Aggregation

    Metric Aggregation 一些数学运算，可以对文档字段进行统计分析。

    1.1 查询员工的最低最高和平均工资

        @Test
    public void testAgg1() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //查询员工的最低最高和平均工资
        MaxAggregationBuilder maxAggregationBuilder = AggregationBuilders.max("maxSalary").field("salary");
        MinAggregationBuilder minAggregationBuilder = AggregationBuilders.min("minSalary").field("salary");
        AvgAggregationBuilder avgAggregationBuilder = AggregationBuilders.avg("avgSalary").field("salary");

        searchSourceBuilder.aggregation(maxAggregationBuilder);
        searchSourceBuilder.aggregation(minAggregationBuilder);
        searchSourceBuilder.aggregation(avgAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println(searchResponse);
        System.out.println("花费的时长：" + searchResponse.getTook());

        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedMax maxSalary = aggregations.get("maxSalary");
        ParsedMin minSalary = aggregations.get("minSalary");
        ParsedAvg avgSalary = aggregations.get("avgSalary");
        System.out.println("maxSalary：" + maxSalary);
        System.out.println("最低工资" + maxSalary.getValue());
        System.out.println("最高工资" + minSalary.getValue());
        System.out.println("平均工资" + avgSalary.getValue());

    }

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    在这里插入图片描述

    1.2 对salary进行统计

        @Test
    public void testAgg2() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //对salary进行统计
        StatsAggregationBuilder statsAggregationBuilder = AggregationBuilders.stats("statSalary").field("salary");

        searchSourceBuilder.aggregation(statsAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedStats statSalary = aggregations.get("statSalary");
        System.out.println("统计个数" + statSalary.getCount());
        System.out.println("平均工资" + statSalary.getAvg());
        System.out.println("最高工资" + statSalary.getMaxAsString()); //可以转String
        System.out.println("最低工资" + statSalary.getMin());
        System.out.println("工资之和" + statSalary.getSum());
    }

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    1.3 cardinate对搜索结果去重统计

       @Test
    public void testAgg3() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //cardinate对搜索结果去重统计
        CardinalityAggregationBuilder cardinalityAggregationBuilder = AggregationBuilders.cardinality("jobCardinate").field("job.keyword");
        searchSourceBuilder.aggregation(cardinalityAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());

        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedCardinality cardinality = aggregations.get("jobCardinate");
        System.out.println("字段：" + cardinality.getName());
        System.out.println("不重复的个数" + cardinality.getValue());
    }


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    2、Bucket Aggregation

    Bucket Aggregation：按照一定的规则，将文档分配到不同的桶中，每一个桶关联一个 key，从而达到分类的目的。类比Mysql中的group by操作。

    2.1 获取 job的分类信息

        @Test
    public void testAgg4() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //获取 job的分类信息
        TermsAggregationBuilder termsAggregationBuilder = AggregationBuilders.terms("jobGroup").field("job.keyword");
        searchSourceBuilder.aggregation(termsAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());
        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedTerms jobGroup = aggregations.get("jobGroup");
        System.out.println("字段：" + jobGroup.getName());
        List<? extends Terms.Bucket> buckets = jobGroup.getBuckets();
        for (Terms.Bucket bucket : buckets) {
            System.out.println("getKey：" + bucket.getKey());
            System.out.println("getKeyAsString：" + bucket.getKeyAsString());
            System.out.println("getDocCount：" + bucket.getDocCount());
        }

    }

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    在这里插入图片描述

    2.2 限定聚合范围

       @Test
    public void testAgg5() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        RangeQueryBuilder rangeQueryBuilder = QueryBuilders.rangeQuery("salary").gte(10000);
        searchSourceBuilder.query(rangeQueryBuilder);

        //获取 job的分类信息
        TermsAggregationBuilder termsAggregationBuilder = AggregationBuilders.terms("jobGroup")
                .field("job.keyword")
                .size(10)
                .order(BucketOrder.aggregation("_count", true));
        searchSourceBuilder.aggregation(termsAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());
        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        //聚合信息
        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedTerms jobGroup = aggregations.get("jobGroup");
        System.out.println("字段：" + jobGroup.getName());
        List<? extends Terms.Bucket> buckets = jobGroup.getBuckets();
        for (Terms.Bucket bucket : buckets) {
            System.out.println("getKey：" + bucket.getKey());
            System.out.println("getKeyAsString：" + bucket.getKeyAsString());
            System.out.println("getDocCount：" + bucket.getDocCount());
        }
    }

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    2.3 Range 示例：按照工资的 Range 分桶

       @Test
    public void testAgg6() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        // Salary Range分桶，可以自己定义 key
        RangeAggregationBuilder rangeAggregationBuilder = AggregationBuilders.range("salary_range")
                .field("salary")
                .addUnboundedTo(10000)
                .addRange(10000, 20000)
                .addUnboundedFrom(">20000", 20000);
        searchSourceBuilder.aggregation(rangeAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());
        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        //聚合信息
        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedRange salaryRange = aggregations.get("salary_range"); //注意类型
        System.out.println("字段：" + salaryRange.getName());
        List<? extends Range.Bucket> buckets = salaryRange.getBuckets();
        for (Range.Bucket bucket : buckets) {
            System.out.println("getKey：" + bucket.getKey());
            System.out.println("getKeyAsString：" + bucket.getKeyAsString());
            System.out.println("getDocCount：" + bucket.getDocCount());
            System.out.println("getFromAsString：" + bucket.getFromAsString());
            System.out.println("getToAsString：" + bucket.getToAsString());
        }
    }

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    在这里插入图片描述

    2.4 Histogram示例：按照工资的间隔分桶

            // Histogram示例：按照工资的间隔分桶
        HistogramAggregationBuilder histogramAggregationBuilder = AggregationBuilders.histogram("salary_histrogram")
                .field("salary")
                .interval(5000)
                .extendedBounds(0, 100000);
        searchSourceBuilder.aggregation(histogramAggregationBuilder);

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    .5 date_histogram 根据年月日做统计和上面类似，可自定义时间格式

    2.6 top_hits示例：

    top_hits应用场景：当获取分桶后，桶内最匹配的顶部文档列表。

        @Test
    public void testAgg8() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        // top_hits示例：指定size，不同工种中，年纪最大的3个员工的具体信息
        TopHitsAggregationBuilder topHitsAggregationBuilder = AggregationBuilders.topHits("old_employee")
                .size(3)
                .sort("age", SortOrder.DESC);

        TermsAggregationBuilder termsAggregationBuilder = AggregationBuilders.terms("jobs")
                .field("job.keyword")
                .subAggregation(topHitsAggregationBuilder); //嵌套聚合
        searchSourceBuilder.aggregation(termsAggregationBuilder);

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());
        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        //聚合信息
        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedTerms jobs = aggregations.get("jobs"); //注意类型
        System.out.println("字段：" + jobs.getName());
        List<? extends Terms.Bucket> buckets = jobs.getBuckets();
        for (Terms.Bucket bucket : buckets) {
            System.out.println("getKey：" + bucket.getKey());
            System.out.println("getKeyAsString：" + bucket.getKeyAsString());
            System.out.println("getDocCount：" + bucket.getDocCount());
            //嵌套的信息
            ParsedTopHits oldEmployee = bucket.getAggregations().get("old_employee");
            SearchHits employeeHits = oldEmployee.getHits();
            System.out.println("    hits.getTotalHits().value：" + hits.getTotalHits().value);
            for (SearchHit employeeHit : employeeHits) {
            System.out.println("    employeeHit.getSourceAsString()：" + employeeHit.getSourceAsString());

            }
        }
    }

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    在这里插入图片描述

    3、Pipeline Aggregation

    Pipeline Aggregation：支持对聚合分析的结果，再次进行聚合分析。

    3.1 min_bucket示例：最小值

    在员工数最多的工种里，找出平均工资最低的工种

        public void testAgg9() throws IOException {
        RestHighLevelClient restHighLevelClient = ESUtil.getRestHighLevelClient();

        //1.创建 SearchRequest搜索请求,并指定要查询的索引
        SearchRequest searchRequest = new SearchRequest("employees");

        //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        // min_bucket示例：平均工资最低的工种
        AvgAggregationBuilder avgAggregationBuilder = AggregationBuilders.avg("avg_salary").field("salary");

        TermsAggregationBuilder termsAggregationBuilder = AggregationBuilders.terms("jobs")
                .field("job.keyword")
                .size(10)
                .subAggregation(avgAggregationBuilder); //嵌套聚合
        searchSourceBuilder.aggregation(termsAggregationBuilder);

        // 添加 bucket pipeline(min_bucket)
        searchSourceBuilder.aggregation(new MinBucketPipelineAggregationBuilder("min_salary_by_job", "jobs>avg_salary"));

        //3.将 SearchSourceBuilder 添加到 SearchRequest中
        searchRequest.source(searchSourceBuilder);

        //4.执行查询
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);

        //5.解析查询结果
        System.out.println("花费的时长：" + searchResponse.getTook());
        SearchHits hits = searchResponse.getHits();
        System.out.println("符合条件的总文档数量：" + hits.getTotalHits().value);
        //聚合信息
        Aggregations aggregations = searchResponse.getAggregations();
        System.out.println("aggregations：" + aggregations);
        ParsedTerms jobs = aggregations.get("jobs"); //注意类型
        System.out.println("字段：" + jobs.getName());
        List<? extends Terms.Bucket> buckets = jobs.getBuckets();
        for (Terms.Bucket bucket : buckets) {
            System.out.println("getKey：" + bucket.getKey());
            System.out.println("getKeyAsString：" + bucket.getKeyAsString());
            System.out.println("getDocCount：" + bucket.getDocCount());
            //嵌套的信息
            ParsedAvg avgSalary = bucket.getAggregations().get("avg_salary");
            System.out.println("    hits.getTotalHits().value：" + avgSalary.getValue());
        }
    }

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    3.2 Stats示例：统计分析

            //2.创建 SearchSourceBuilder条件构造。
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        // Stats示例：统计分析：平均工资的统计分析
        AvgAggregationBuilder avgAggregationBuilder = AggregationBuilders.avg("avg_salary").field("salary");

        TermsAggregationBuilder termsAggregationBuilder = AggregationBuilders.terms("jobs")
                .field("job.keyword")
                .size(10)
                .subAggregation(avgAggregationBuilder); //嵌套聚合
        searchSourceBuilder.aggregation(termsAggregationBuilder);

        // 添加 bucket pipeline(stats_bucket)
        searchSourceBuilder.aggregation(new StatsBucketPipelineAggregationBuilder("stats_salary_by_job", "jobs>avg_salary"));

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    到此，Java 操作 RestHighLevelClient查询基本就 ok了。

    总结如下：

    • 写好 ES语句很关键，然后通过 客户端编写出来就简单了。
    • 创建 SearchSourceBuilder条件构造，构建搜索的条件很重要，根据业务构造r条件变化多端。
    • 不管是 Query DSL还是 聚合操作，通过 ES语句的结果来编写 SearchResponse的解析查询结果就很容易了，注意里边的类型。

    – 求知若饥，虚心若愚。

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  • 原文地址：https://blog.csdn.net/qq_42402854/article/details/126615064