ElasticSearch : High Rest Api 使用

pom文件:

<dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>7.2.0</version>
</dependency>

創建client(client可以關閉, 建議在停止應用前調用close() 方法):

RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("10.8.3.55", 9200, "http")));

// 1. 檢測索引是否存在(所有和索引有關的操作全部推薦用org.elasticsearch.client.indices包下的類)
        GetIndexRequest request = new GetIndexRequest("twitter");
        boolean exists = client.indices().exists(request, RequestOptions.DEFAULT);
        System.out.println(exists);

// 2. 創建索引
        CreateIndexRequest request = new CreateIndexRequest("twitter");
        request.settings(Settings.builder()
                .put("index.number_of_shards", 1)
                .put("index.number_of_replicas", 1)
        );

        // 第一種
        request.mapping("{\"properties\":{\"msg\":{\"type\":\"text\"}}}", XContentType.JSON);

        // 第二種
        Map<String, Object> properties = new HashMap<>();// properties

        Map<String, Object> message = new HashMap<>();
        message.put("type", "text");
        properties.put("message", message);// 添加映射
        Map<String, Object> username = new HashMap<>();
        username.put("type", "keyword");
        properties.put("username", username);// 添加映射

        Map<String, Object> mapping = new HashMap<>();
        mapping.put("properties", properties);
        request.mapping(mapping);

        CreateIndexResponse createIndexResponse = client.indices().create(request, RequestOptions.DEFAULT);
        System.out.println(createIndexResponse.index());

// 3. 增加文檔(如果類注釋推薦使用org.elasticsearch.client.Requests來創建類,最好用他推薦的方式)
        IndexRequest request = Requests.indexRequest("twitter");
        request.id("1");// 指定ID
        request.source("message", "消息內容...abc",
                "username", "jack 傑克");// 支持多種方式
        IndexResponse indexResponse = client.index(request, RequestOptions.DEFAULT);
        System.out.println(indexResponse);

// 4. 修改文檔
        UpdateRequest request = new UpdateRequest("twitter", "1");
        request.doc("message", "修改之后的消息內容...abc",
                "username", "修改之后的jack 傑克");// 支持多種方式
        UpdateResponse response = client.update(request, RequestOptions.DEFAULT);
        System.out.println(response);

// 5. Bulk
        BulkRequest request = new BulkRequest();
        request.add(new DeleteRequest("twitter", "1"));
        request.add(new UpdateRequest("twitter", "2")
                .doc(XContentType.JSON,"username", "jack==="));
        request.add(new IndexRequest("twitter").id("3")
                .source(XContentType.JSON,"username", "jack222"));

        BulkResponse response = client.bulk(request, RequestOptions.DEFAULT);
        System.out.println(response.hasFailures());

// 6. 根據ID獲取文檔
        GetRequest request = Requests.getRequest("twitter").id("2");
        GetResponse response = client.get(request, RequestOptions.DEFAULT);
        System.out.println(response.getSourceAsString());

        // 7. Search
        SearchRequest request = new SearchRequest("twitter");
        SearchSourceBuilder builder = new SearchSourceBuilder();
        builder.query(QueryBuilders.matchAllQuery());
        request.source(builder);
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        Iterator<SearchHit> hits = response.getHits().iterator();
        ObjectMapper mapper = new ObjectMapper();
        List<Person> personList = new ArrayList<>();
        while (hits.hasNext()) {
            personList.add(mapper.readValue(hits.next().getSourceAsString(), Person.class));
        }
        System.out.println(personList);

查詢聚合DSL語句構建使用 SearchSourceBuilder:

//   樣例 偽代碼:

//        SearchSourceBuilder builder = new SearchSourceBuilder();
//        String[] include = {"timeStamp",
//                "msgBody.boxList.boxStatus.boxCurrent",
//                "msgBody.boxList.batInfo.batSN",
//                "msgBody.boxList.batStatus.batCurrent",
//                "msgBody.boxList.batStatus.batVoltage",
//                "msgBody.boxList.batStatus.batRSOC"};
//        builder.query(QueryBuilders.boolQuery()
////                .filter(QueryBuilders.termQuery("msgBody.boxList.batInfo.batSN", "BAA2118122200104"))
//                .filter(QueryBuilders.rangeQuery("timeStamp").gte(1557729000).lte(1557741600)))
//                .sort("timeStamp", SortOrder.ASC)
//                .from(0)
//                .size(100).fetchSource(include, null);
////        builder.aggregation(AggregationBuilders.terms("data_count").field("deviceInfo.deviceSN")).size(0);

High Rest client使用參考 https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high.html

聚合結果分析參考: https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/_bucket_aggregations.html

獲取聚合必須要指定相關的類 如 Terms:

Terms data = response.getAggregations().get("data_count");
        System.out.println(data.getBuckets().get(0).getKey());
        System.out.println(data.getBuckets().get(0).getDocCount());
        System.out.println(response.toString());