SpringBoot整合Elasticsearch：检索数据

Elasticsearch检索数据，请参考：https://www.jianshu.com/p/6b58dcac4fc8。
测试数据来自：https://github.com/elastic/elasticsearch/blob/master/docs/src/test/resources/accounts.json，在Kibana中执行：POST bank/account/_bulk。

1、Elasticsearch检索示例

搜索address中包含mill的所有人的年龄分布以及平均年龄。

GET bank/_search
{
    "query": {
        "match": {
            "address": {
                "query": "mill"
            }
        }
    },
    "aggregations": {
        "ageTerm": {
            "terms": {
                "field": "age",
                "size": 10
            }
        },
        "ageAvg": {
            "avg": {
                "field": "age"
            }
        }
    }
}

执行结果：

{
  "took" : 3,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 4,
      "relation" : "eq"
    },
    "max_score" : 5.4032025,
    "hits" : [
      {
        "_index" : "bank",
        "_type" : "account",
        "_id" : "970",
        "_score" : 5.4032025,
        "_source" : {
          "account_number" : 970,
          "balance" : 19648,
          "firstname" : "Forbes",
          "lastname" : "Wallace",
          "age" : 28,
          "gender" : "M",
          "address" : "990 Mill Road",
          "employer" : "Pheast",
          "email" : "forbeswallace@pheast.com",
          "city" : "Lopezo",
          "state" : "AK"
        }
      },
      {
        "_index" : "bank",
        "_type" : "account",
        "_id" : "136",
        "_score" : 5.4032025,
        "_source" : {
          "account_number" : 136,
          "balance" : 45801,
          "firstname" : "Winnie",
          "lastname" : "Holland",
          "age" : 38,
          "gender" : "M",
          "address" : "198 Mill Lane",
          "employer" : "Neteria",
          "email" : "winnieholland@neteria.com",
          "city" : "Urie",
          "state" : "IL"
        }
      },
      {
        "_index" : "bank",
        "_type" : "account",
        "_id" : "345",
        "_score" : 5.4032025,
        "_source" : {
          "account_number" : 345,
          "balance" : 9812,
          "firstname" : "Parker",
          "lastname" : "Hines",
          "age" : 38,
          "gender" : "M",
          "address" : "715 Mill Avenue",
          "employer" : "Baluba",
          "email" : "parkerhines@baluba.com",
          "city" : "Blackgum",
          "state" : "KY"
        }
      },
      {
        "_index" : "bank",
        "_type" : "account",
        "_id" : "472",
        "_score" : 5.4032025,
        "_source" : {
          "account_number" : 472,
          "balance" : 25571,
          "firstname" : "Lee",
          "lastname" : "Long",
          "age" : 32,
          "gender" : "F",
          "address" : "288 Mill Street",
          "employer" : "Comverges",
          "email" : "leelong@comverges.com",
          "city" : "Movico",
          "state" : "MT"
        }
      }
    ]
  },
  "aggregations" : {
    "ageAvg" : {
      "value" : 34.0
    },
    "ageTerm" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : 38,
          "doc_count" : 2
        },
        {
          "key" : 28,
          "doc_count" : 1
        },
        {
          "key" : 32,
          "doc_count" : 1
        }
      ]
    }
  }
}

2、SpringBoot整合Elasticsearch检索

SpringBoot整合Elasticsearch请参考：https://www.jianshu.com/p/6a99d6d0ec66，本文以此为基础继续讨论。

    @Test
    void searchData() throws IOException {
        //1、创建检索请求
        SearchRequest searchRequest = new SearchRequest();
        //2、指定索引
        searchRequest.indices("bank");

        //3、创建检索条件
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        //3.1、“address中包含mill”
        sourceBuilder.query(QueryBuilders.matchQuery("address","mill"));
        //3.2、“年龄分布”，根据年龄聚合
        TermsAggregationBuilder ageAgg = AggregationBuilders.terms("ageTerm").field("age").size(10);
        sourceBuilder.aggregation(ageAgg);
        //3.3、计算“平均年龄”
        AvgAggregationBuilder ageAvg = AggregationBuilders.avg("ageAvg").field("age");
        sourceBuilder.aggregation(ageAvg);

        System.out.println("检索条件："+sourceBuilder.toString());
        searchRequest.source(sourceBuilder);

        //4、执行检索
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
        System.out.println(searchResponse);

        //4.1、获取所有查到的数据,这个hits是最外面的hits，里面还有很多小hits
        SearchHits hits = searchResponse.getHits();
        //4.2、获取到各个数据
        SearchHit[] data = hits.getHits();
        for (SearchHit datum : data) {
            /**    {
             *         "_index" : "bank",
             *         "_type" : "account",
             *         "_id" : "970",
             *         "_score" : 5.4032025,
             *         "_source" : {
             *           "account_number" : 970,
             *           "balance" : 19648,
             *           ...
             *         }
             *       }
             */
            String id = datum.getId();
            System.out.println(id);
            String sourceAsString = datum.getSourceAsString();
            Object account = JSON.parseObject(sourceAsString, Account.class);
            System.out.println("Account: "+account);
        }
        //4.3、获取检索到的聚合数据
        /**
         * "aggregations" : {
         *     "ageAvg" : {
         *       ...
         *     },
         *     "ageTerm" : {
         *       ...
         *     }
         *   }
         */
        Aggregations aggregations = searchResponse.getAggregations();
        /**
         *    "ageTerm" : {
         *       "doc_count_error_upper_bound" : 0,
         *       "sum_other_doc_count" : 0,
         *       "buckets" : [
         *         {
         *           "key" : 38,
         *           "doc_count" : 2
         *         },
         *         ...
         *       ]
         *     }
         */
        Terms ageTerm = aggregations.get("ageTerm");
        /**
         *      "buckets": [{
         *          "key": 38,
         *          "doc_count": 2
         *       }, {
         *          "key": 28,
         *          "doc_count": 1
         *       }, {
         *          "key": 32,
         *          "doc_count": 1
         *       }]
         */
        for (Terms.Bucket bucket : ageTerm.getBuckets()) {
            System.out.println("年龄: "+ bucket.getKeyAsString()+"，人数："+bucket.getDocCount());
        }

        /**
         *  "ageAvg": {
         *      "value": 34.0
         *   }
         */
        Avg avg = aggregations.get("ageAvg");
        System.out.println("平均年龄："+avg.getValue());

    }