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es中几种常见的查询场景,使用java读取es的json文件进行查询。

es 中文使用手册。
https://www.elastic.co/guide/cn/elasticsearch/guide/current/foreword_id.html

1.  从最简单的查询开始

GET /_search

{"hits" : {"total" :       14,"hits" : [{"_index":   "us","_type":    "tweet","_id":      "7","_score":   1,"_source": {"date":    "2014-09-17","name":    "John Smith","tweet":   "The Query DSL is really powerful and flexible","user_id": 2}},... 9 RESULTS REMOVED ...],"max_score" :   1},"took" :           4,"_shards" : {"failed" :      0,"successful" :  10,"total" :       10},"timed_out" :      false
}

从官方给的例子看下这些参数的含义。
hits 结果集
    - _index document的属性
    - type document的属性
    - _id document的属性
    - _score 对搜索的匹配性(越匹配,得分越高)
    - _source 就是存进去的value
took 请求花费时间
timeout 超时时间(默认不超时,可以指定 GET /_search?timeout=10ms)
shards 有多少个响应的分片,多少成功/失败
之所以hits 要多返回几个document的属性，避免需要的时候再去查询。

2.  稍微麻烦的查询

sql 一般都会写，介绍一个神器
神器：    Sql 转 Es 查询语句 
http://www.ischoolbar.com/EsParser/

举个例子
sql：

select name,number from sys_user order by create_time desc limit 10

es query：

{"from":0,"size":"10","sort":[{"create_time":{"order":"DESC"}}],"_source":{"include":["name","number"]}}

如图所示：

上面的例子还是太简单了，如果想做分组后求和呢。
如图所示：

3.  es数据展示

这次模拟的是二次分组的数据情况,某个时间段的按分钟分组,获取有多少分钟,再获取这一分钟内数据的分组情况(每分钟有多少数据)。
es sql ：uid_aggs 代表第一次分组的字段,keyword_aggs 是第二次分组后的详情数据

{"aggs": {"all": {"terms": {"field": "currentMinutes.keyword","size": 100}},"keyword_aggs": {"aggs": {"top": {"top_hits": {"size": 100}}},"terms": {"field": "currentMinutes.keyword","size": 100}},"uid_aggs": {"cardinality": {"precision_threshold": 120,"field": "currentMinutes.keyword"}}},"query": {"bool": {"must": [{"range": {"currentTime.keyword": {"gte": "2020-08-05 14:43","lte": "2020-08-05 14:45"}}}],"must_not": [],"should": []}},"sort": [{"currentTime.keyword": {"order": "desc"}}]
}

结果：
我把返回的详细数据hits删掉了，主要看一下 aggregations 里边的内容。
返回的参数说明：
uid_aggs 就是请求查询传入的参数,这里返回的是,按分钟分组的数量。
all的buckets 的key为二次分组字段,doc_count 为二次分组对应的数据量。
keyword_aggs的 buckets 展示了all的buckets 对应的数据详情。

{"took": 5,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 5,"max_score": null,"hits": [{// 数据暂时删掉了...}]},"aggregations": {"all": {"doc_count_error_upper_bound": 0,"sum_other_doc_count": 0,"buckets": [{"key": "2020-08-05 14:44","doc_count": 3},{"key": "2020-08-05 14:43","doc_count": 2}]},"uid_aggs": {"value": 2},"keyword_aggs": {"doc_count_error_upper_bound": 0,"sum_other_doc_count": 0,"buckets": [{"key": "2020-08-05 14:44","doc_count": 3,"top": {"hits": {"total": 3,"max_score": 1.0,"hits": [{"_index": "apm-report-app2020-08-05","_type": "info","_id": "7cpdvXMBjkzeFkDgwB3t","_score": 1.0,"_source": {"dvid": "D3B6D5FBC668B731E52BC08D9FE23EAB","showName": "车系列表","appVer": "10.36.0","groupId": 3,"weight": 1,"pageId": 30001,"apiTime": 541.3210391998291,"platform": 2,"currentTime": "2020-08-05 14:44:53.292","loadTime": 584.99908447265625,"@timestamp": "2020-08-05 14:44:53","currentMinutes": "2020-08-05 14:44","viewTime": 43.678998947143555,"requestId": "BD43986C-7995-4F93-84F7-B4D65E8BE5EB","cName": "BPCSerialListRootVC"}},{"_index": "apm-report-app2020-08-05","_type": "info","_id": "7spdvXMBjkzeFkDgxh2B","_score": 1.0,"_source": {"dvid": "D3B6D5FBC668B731E52BC08D9FE23EAB","showName": "车型综述页","appVer": "10.36.0","groupId": 3,"weight": 1,"pageId": 30007,"apiTime": 456.7570686340332,"platform": 2,"currentTime": "2020-08-05 14:44:54.721","loadTime": 720.36707401275635,"@timestamp": "2020-08-05 14:44:54","currentMinutes": "2020-08-05 14:44","viewTime": 263.61000537872314,"requestId": "DCE5F4A4-40AC-4EB4-BCCF-ABACCFC7FF01","cName": "BPCOverPagesViewController"}},{"_index": "apm-report-app2020-08-05","_type": "info","_id": "78pdvXMBjkzeFkDgyB1A","_score": 1.0,"_source": {"dvid": "D3B6D5FBC668B731E52BC08D9FE23EAB","showName": "车型-图片列表","appVer": "10.36.0","groupId": 3,"weight": 1,"pageId": 30015,"apiTime": 129.27305698394775,"platform": 2,"currentTime": "2020-08-05 14:44:55.168","loadTime": 150.16889572143555,"@timestamp": "2020-08-05 14:44:55","currentMinutes": "2020-08-05 14:44","viewTime": 20.89691162109375,"requestId": "A1DA2749-A56B-4AFE-BF83-ECDF82806152","cName": "BPImageVideoViewController"}}]}}},{"key": "2020-08-05 14:43","doc_count": 2,"top": {"hits": {"total": 2,"max_score": 1.0,"hits": [{"_index": "apm-report-app2020-08-05","_type": "info","_id": "7MpcvXMBjkzeFkDg2x17","_score": 1.0,"_source": {"dvid": "D3B6D5FBC668B731E52BC08D9FE23EAB","showName": "车型-图片列表","appVer": "10.36.0","groupId": 3,"weight": 1,"pageId": 30015,"apiTime": 269.10901069641113,"platform": 2,"currentTime": "2020-08-05 14:43:54.553","loadTime": 334.06901359558105,"@timestamp": "2020-08-05 14:43:54","currentMinutes": "2020-08-05 14:43","viewTime": 64.961075782775879,"requestId": "E5105DA7-5914-41ED-A76E-5DF39CF38588","cName": "BPImageVideoViewController"}},{"_index": "apm-report-app2020-08-05","_type": "info","_id": "68pcvXMBjkzeFkDg1h2t","_score": 1.0,"_source": {"dvid": "D3B6D5FBC668B731E52BC08D9FE23EAB","showName": "车型综述页","appVer": "10.36.0","groupId": 3,"weight": 1,"pageId": 30007,"apiTime": 488.01600933074951,"platform": 2,"currentTime": "2020-08-05 14:43:53.324","loadTime": 539.05403614044189,"@timestamp": "2020-08-05 14:43:53","currentMinutes": "2020-08-05 14:43","viewTime": 51.03909969329834,"requestId": "B370AB84-3A6E-4C48-9DF2-4F6E1855567B","cName": "BPCOverPagesViewController"}}]}}}]}}
}

4.  Java代码转换

将写好的es json放到 resouces目录下，变量用唯一字符表示，等读取sql的时候再替换。
读取resources下json的代码。

/*** 加载查询* @param path 路径* @return string*/
private String getQueryJsonStr(String path) {//加载json文件ClassPathResource classPathResource = new ClassPathResource(path);String queryJson=null;try (InputStream in = classPathResource.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(in))) {StringBuilder message = new StringBuilder();String line = null;while ((line = br.readLine()) != null) {message.append(line);}queryJson = message.toString();} catch (Exception e) {}return queryJson;
}

拼装替换的map参数,这里以时间为例

/*** es查询时间* @param beginTime beginTime* @param endTime endTime* @return Map*/private Map<String,String> buildEsQueryMap(String beginTime, String endTime){Map<String,String> params = new HashMap<>();//初始化时间if (StringUtils.isEmpty(beginTime)){beginTime = DateUtil.getCurrDate()+" 00:00:00";}if (StringUtils.isEmpty(endTime)){endTime = DateUtil.getCurrTime();//当前时间}params.put("{beginTime}", beginTime);params.put("{endTime}", endTime);return params;}

遍历替换json

for (Map.Entry<String, String> entry : params.entrySet()) {queryJson=queryJson.replace(entry.getKey(), entry.getValue());
}

发送http请求查询,queryJson就是替换后的es查询json

HttpHeaders headers = new HttpHeaders();
MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
headers.setContentType(type);
headers.add("Accept", MediaType.APPLICATION_JSON.toString());
HttpEntity<String> formEntity = new HttpEntity<>(queryJson, headers);
//查询
result= restTemplate.postForEntity(url,formEntity,JSONObject.class).getBody();

5. 总结

es的学习成本确实有点高,文档又多又杂。更多的看官方文档吧。
英文版：
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-search.html
中文版：（基于 Elasticsearch 2.x 版本）
https://www.elastic.co/guide/cn/elasticsearch/guide/current/query-dsl-intro.html