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Java 操作之RestHighLevelClient查询详解

智云科技 发布于 2023年3月14日 评论关闭 阅读(90)

一、高级查询Query DSL

Elasticsearch 高级查询Query DSL：

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  Search SourceBuilder 添加到 Search Request 中
4、执行查询
5、解析查询结果

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 IO Exception  {
 
        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(matchAll Query Builder);

        //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()));
    }

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()));
    }

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()));
    }

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()));
    }

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()));
    }

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()));
    }

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);

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);

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);

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);

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("<font color='red'>");
        highlightBuilder.postTags("</font>");
        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());
        });
    }

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);

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);

二、聚合操作

ElasticSearch聚合操作：

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());

    }

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());
    }

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());
    }

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());
        }

    }

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());
        }
    }

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());
        }
    }

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);

.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());

            }
        }
    }

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());
        }
    }

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"));

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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文章来源：智云一二三科技

文章标题：Java 操作之RestHighLevelClient查询详解

文章地址：https://www.zhihuclub.com/185356.shtml

关于作者: 智云科技

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