ElasticSearch查询工具类分享

前言
最近需要对ES数据进行分析和查询， 之前因为在入门ES时没有好好做笔记和整理 。

1. sql转ES工具

https://printlove.cn/tools/sql2es/
可以把基本的sql查询条件 转成es查询条件 ， 适当的使用的可以增加自己写es的效果

2. Kibana VS Postman /ApiPost

一般在写java ES查询时， 习惯先用 kibana 或者postman 构建ES 查询json,
其实两个工具各有优势，

• kibana 的优势是具备词语提示 ，只能请求kibana绑定的es地址
  
• postman的优势是可以注释json , 请求多个ES地址（ 比如开发、测试环境）
  

两个工具都还不错， 个人偏向于postman 一点，因为注释 调试起来比较方便。

3 .es json 转java

按照json的结构，可以轻松的写出java代码 ，根据query key的名称，使用QueryBuilders 构建 , 根据aggs （aggregations 的简称） key的名称,使用AggregationBuilders构建 ， 示例如下

• 示例json

{
  "query": {
    "bool": {
      "must": [
        {
          // 时间范围
          "range": {
            "create_at": {
              "from": "2023-09-01",
              "to": "2023-09-12"
            }
          }
        },
          // 分值
        {
          "exists": {
            "field": "score"
          }
        }
      ]
    }
  },
  "aggs": {
    "name_group": {
      // 根据name分组 ,根据每组最大score排序 
      "terms": {
        "field": "name",
        "order": {
          "max_score": "desc"
        }
      },
      "aggs": {
        // 最大分值
        "max_score": {
          "max": {
            "field": "score"
          }
        }
      }
    }
  }
}

• java示例

          // query --> java
        BoolQueryBuilder conditionsBoolQuery =QueryBuilders.boolQuery()
                .must(QueryBuilders.rangeQuery("create_at").from(query.getStartDateTimestamp()).to(query.getEndDateTimestamp()))
                .must(QueryBuilders.existsQuery("location.county_code"));

        // agg -->java
        AggregationBuilder aggGroup = AggregationBuilders
                .terms("name_group").field("name").order(BucketOrder.aggregation("max_score", false))
                .subAggregation(AggregationBuilders.max("max_score").field("score"));

创建请求即可
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder().query(conditionsBoolQuery).aggregation(aggGroup);

4. ElasticSearch查询工具类 esHelper

当使用RestHighLevelClient 进行es请求时 ， 关心转换 的searchSourceBuilder 入参对不对 ？ searchResponse 出参对不对？ 那么需要对es对象进行json序列化 。
当你查看es源码时 ，大部分es对象都是继承自ToXContent 对象， 而XContentBuilder 支持ToXContent 对象的自定义转换 。所以封装esHelper 方便查看调用RestHighLevelClient 入参和出参。

@Slf4j
@Component
public class EsHelper {

    @Resource
    private RestHighLevelClient client;

    private ObjectMapper mapper;

    @Value("${eshelper.debug:false}")
    private boolean debug;

    @PostConstruct
    public void init() {
        mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
        mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        // 下划线转驼峰
        mapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
    }

    /**
     * 获取查询数量
     *
     * @param queryBuilder 查询器
     * @param indexes      索引目录
     */
    public long count(QueryBuilder queryBuilder, String... indexes) throws IOException {
        CountRequest countRequest = new CountRequest(indexes);
        countRequest.query(queryBuilder);
        client.count(countRequest, RequestOptions.DEFAULT);
        CountResponse countResponse = client.count(countRequest, RequestOptions.DEFAULT);
        return countResponse.getCount();
    }


    /**
     * 获取查询列表 List
     */
    public <T> List<T> listHits(Class<T> entityClass, SearchSourceBuilder sourceBuilder, String... indexes) throws IOException {
        return listHits(mapper.getTypeFactory().constructType(entityClass), sourceBuilder, indexes);
    }

    /**
     * 获取查询列表 List>
     */
    public List<Map<String, Object>> listHits(SearchSourceBuilder sourceBuilder, String... indexes) throws IOException {
        return listHits(mapper.getTypeFactory().constructParametricType(Map.class, String.class, Object.class), sourceBuilder, indexes);

    }

    /**
     * 从Hits 获取结果
     *
     * @param javaType      动态java类型
     * @param sourceBuilder 查询构建器
     * @param indexes       引目录
     * @throws IOException
     */
    private <T> List<T> listHits(JavaType javaType, SearchSourceBuilder sourceBuilder, String... indexes) throws IOException {
        Map<String, List<T>> resultMap = new HashMap<>();
        responseFilter(searchResponse -> {
            SearchHit[] hits = searchResponse.getHits().getHits();
            resultMap.put("result", hits2List(javaType, hits));
        }, sourceBuilder, indexes);
        return resultMap.getOrDefault("result", null);
    }


    /**
     * 转换hits为java List对象
     */
    public <T> List<T> hits2List(JavaType javaType, SearchHit[] hits) {
        List<T> resultList = new ArrayList<>();
        for (SearchHit hit : hits) {
            try {
                Map<String, Object> source = hit.getSourceAsMap();
                source.put("id", hit.getId());
                T result = mapper.readValue(mapper.writeValueAsString(source), javaType);
                resultList.add(result);
            } catch (Exception e) {
                log.error("hit 转换对象异常!", e);
            }
        }
        return resultList;
    }


    public <T> T toBean(String str, Class<T> entityClass) throws JsonProcessingException {
        return mapper.readValue(str, mapper.constructType(entityClass));
    }

    /**
     * @param responseConsumer response消费者
     * @param sourceBuilder    查询构建器
     * @param indexes          索引
     */
    public void responseFilter(ResponseConsumer responseConsumer, SearchSourceBuilder sourceBuilder, String... indexes) throws IOException {
        SearchRequest searchRequest = new SearchRequest(indexes);
        searchRequest.source(sourceBuilder);
        if (debug) {
            log.info("ES Request json==>{}", toStringEsObject(sourceBuilder, true));
        }
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
        if (debug) {
            log.info("ES Response json==>{} ", toStringEsObject(searchResponse, false));
        }
        responseConsumer.accept(searchResponse);
    }


    /**
     * 转换es对象 为json文本
     */
    protected String toStringEsObject(ToXContent xContent, boolean prettyPrint) {
        XContentBuilder xContentBuilder = null;
        try {
            xContentBuilder = XContentBuilder.builder(XContentType.JSON.xContent());
            xContent.toXContent(xContentBuilder, ToXContent.EMPTY_PARAMS);
            return XContentHelper.convertToJson(BytesReference.bytes(xContentBuilder), prettyPrint, prettyPrint, XContentType.JSON);
        } catch (IOException e) {
            log.error("ES对象转json字符串失败: !!!!", e);
        }
        return null;
    }


    @FunctionalInterface
    public interface ResponseConsumer {
        public void accept(SearchResponse searchResponse);
    }
}

5. 在IDE 控制台看到效果如图

ES Request json 输出SearchRequest json ，可以复制json对象至postman或 kibana 查看效果是不是正确

ES Response json输出SearchResponse json ，可以根据json 对象检查结果是否正确