【ES RestHighLevelClient】API使用

1.ES提供了兩個JAVA REST client 版本

Java Low Level REST Client: 低級別的REST客戶端，通過http與集群交互，用戶需自己編組請求JSON串，及解析響應JSON串。兼容所有ES版本。

Java High Level REST Client: 高級別的REST客戶端，基於低級別的REST客戶端，增加了編組請求JSON串、解析響應JSON串等相關api。使用的版本需要保持和ES服務端的版本一致，否則會有版本問題。

2.創建連接

@Override
public RestHighLevelClient elasticsearchClient() {
    final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY,
            new UsernamePasswordCredentials(username, password));  //es賬號密碼（默認用戶名為elastic）
    RestHighLevelClient client = new RestHighLevelClient(
            RestClient.builder(
                    new HttpHost(esHost, esPort, "http"))
                    .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                        public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                            httpClientBuilder.disableAuthCaching();
                            return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
                        }
                    }));
    return client;
}

@Bean
public RestHighLevelClient esRestClient(){
    final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY,
            new UsernamePasswordCredentials(username, password));  //es賬號密碼（默認用戶名為elastic）
    RestHighLevelClient client = new RestHighLevelClient(
            RestClient.builder(
                    new HttpHost(esHost, esPort, "http"))
                    .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                        public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                            httpClientBuilder.disableAuthCaching();
                            return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
                        }
                    }));
    return client;
}

3.執行查詢

SearchRequest 搜索請求對象
SearchSourceBuilder 搜索內容參數設置對象

SearchRequest searchRequest = new SearchRequest(); //首先創建搜索請求對象
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();//創建搜索內容參數設置對象
searchSourceBuilder.query(boolQueryBuilder);//設置搜索條件
searchRequest.source(searchSourceBuilder);//將SearchSourceBuilder對象添加到搜索請求中

SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
//開始位置
sourceBuilder.from(from);
//每頁數量
sourceBuilder.size(size);
//排序
sourceBuilder.sort("timeEnd", SortOrder.DESC);
//搜索請求對象
SearchRequest rq = new SearchRequest();
//索引
rq.indices(index);
//各種組合條件
rq.source(sourceBuilder);
//請求
SearchResponse rp = client().search(rq);

4.查詢語句構建

4.1.構建查詢語句

BoolQueryBuilder queryBuilder = boolQuery();

4.2查詢條件組合關系

must: AND
mustNot: NOT
should: OR should: OR

queryBuilder.must(QueryBuilders.termQuery("user", "kimchy"))
.mustNot(QueryBuilders.termQuery("message", "nihao"))
.should(QueryBuilders.termQuery("gender", "male"));

4.3 查詢子條件

matchQuery：會將搜索詞分詞，再與目標查詢字段進行匹配，若分詞中的任意一個詞與目標字段匹配上，則可查詢到。
termQuery：不會對搜索詞進行分詞處理，而是作為一個整體與目標字段進行匹配，若完全匹配，則可查詢到。

4.3.1 matchAllQuery匹配所有

QueryBuilders.matchAllQuery();

4.3.2 termQuery精准匹配

QueryBuilders.termQuery("key", value)//匹配一個
QueryBuilders.termsQuery("key", obj1, obj2..)  //匹配多個

4.3.3 matchPhraseQuery對中文精確匹配

QueryBuilders.matchPhraseQuery("key", value)

4.3.4 matchQuery 單個匹配（分詞匹配）

QueryBuilders.matchQuery(key, value)

4.3.5 multiMatchQuery("text", "field1", "field2"..)匹配多個字段, field有通配符就行

QueryBuilders.multiMatchQuery(value, key1, key2, key3);

4.3.6 matchPhrasePrefixQuery 左前綴匹配

QueryBuilders.matchPhrasePrefixQuery(key, value);

4.3.7wildcard query 通配符查詢，支持 * 任意字符串；？任意一個字符

QueryBuilders.wildcardQuery("channelCode","*ctr*")

5.一些查詢例子

/**
 * 精確匹配查詢
 */
@GetMapping("/termQuery")
public void termQuery1(){
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    boolQueryBuilder.must(QueryBuilders.termQuery("name","新頁工廠測試"));
    Iterable<EsStudent> search = esStudentRepository.search(boolQueryBuilder);
}


/**
 * 模糊查詢
 */
@GetMapping("/likeQuery")
public void likeQuery(){
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    boolQueryBuilder.must(QueryBuilders.wildcardQuery("name","*2019*"));
    Iterable<EsStudent> search = esStudentRepository.search(boolQueryBuilder);

}


/**
 * 空值查詢 null 或者空字符串
 */
@GetMapping("/nullQuery")
public void nullQuery(){
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    //構建子查詢
    BoolQueryBuilder userUnitBuilder = boolQuery();
    //不存在該字段
    userUnitBuilder.should(QueryBuilders.boolQuery().mustNot(existsQuery("name")));
    //字段為""
    userUnitBuilder.should(termQuery("name", ""));
    boolQueryBuilder.must(userUnitBuilder);
    Iterable<EsStudent> search = esStudentRepository.search(boolQueryBuilder);

}

/**
 * 字段不為空查詢
 */
@GetMapping("/notNullQuery")
public void notNullQuery(){
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    //構建子查詢
    BoolQueryBuilder userUnitBuilder = boolQuery();
    //不存在該字段
    userUnitBuilder.should(QueryBuilders.boolQuery().mustNot(existsQuery("name")));
    //字段為""
    userUnitBuilder.should(termQuery("name", ""));
    boolQueryBuilder.mustNot(userUnitBuilder);
    
    Iterable<EsStudent> search = esStudentRepository.search(boolQueryBuilder);
}

/**
 * 左前綴匹配
 */
@GetMapping("/prefixQuery")
public void prefixQuery1(){
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    boolQueryBuilder.must(prefixQuery("name","新頁"));
    Iterable<EsStudent> search = esStudentRepository.search(boolQueryBuilder);
}


/**
 * 獲取數據條數
 */
@GetMapping("/countStudent")
public String countStudent() throws IOException {
    // 通過CountRequest查詢獲得count
    CountRequest countRequest = new CountRequest();
    SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    boolQueryBuilder.must(prefixQuery("name","新頁"));
    sourceBuilder.query(boolQueryBuilder);
    // 綁定索引名
    countRequest.indices("es_student");
    countRequest.source(sourceBuilder);
    CountResponse response = restHighLevelClient.count(countRequest, RequestOptions.DEFAULT);
    long count=response.getCount();
    return count+"";
}

/**
 * 聚合統計
 */
@GetMapping("/aggStudent")
public String aggStudent() throws IOException {
    SearchRequest request = new SearchRequest(STUDENT_INDEX);
    SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
    BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    boolQueryBuilder.must(prefixQuery("name","新頁"));
    sourceBuilder.query(boolQueryBuilder);
    ValueCountAggregationBuilder peopleNum = AggregationBuilders.count("peopleNum").field("name");
    SumAggregationBuilder totalAge = AggregationBuilders.sum("totalAge").field("age");
    request.source(sourceBuilder);
    sourceBuilder.size(0);
    request.source().aggregation(peopleNum);
    request.source().aggregation(totalAge);
    SearchResponse search =restHighLevelClient.search(request, RequestOptions.DEFAULT);

    //統計處理結果集
    Map<String, Aggregation> resultMap = search.getAggregations().asMap();
    Aggregation peopleNumAgg = resultMap.get("peopleNum");
    Aggregation totalAgeAgg = resultMap.get("totalAge");
    double totalAgeD = ((ParsedSum) totalAgeAgg).getValue();
    long peopleNumL = ((ParsedValueCount) peopleNumAgg).getValue();

    return "總人數:"+peopleNumL+"  總年齡:"+totalAgeD;
}