[ElasticSearch]ES操作之基本查詢,基於elasticsearch-rest-high-level-client

JAVA操作ES之查詢:

　　首先,高版本客戶端是依賴低版本客戶端的,所以要同時引入低版本依賴

　　其次,客戶端只是提供連接,實際的操作還要引入es的依賴

具體:

        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-high-level-client</artifactId>
            <version>${elasticsearch.version}</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
            <version>${elasticsearch.version}</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>${elasticsearch.version}</version>
        </dependency>

在操作之前,我們要清楚的是,使用java操作es和使用Kibana是一樣的,所以我們要提供的無非是:

　　主機ip

　　端口

　　索引

　　類型

索引的創建不寫,因為一般我們是沒有權限進行索引操作的,索引都是建立好的

查詢的基本代碼如下:

import org.apache.http.HttpHost;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.search.SearchType;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.MatchAllQueryBuilder;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.builder.SearchSourceBuilder;
    @Test
    public void testES(){
        //創建低級客戶端,提供ip,端口,設置超時重試時間
        RestClient restClient = RestClient.builder(new HttpHost("localhost",9200))
                .setMaxRetryTimeoutMillis(300000).build();
        //創建高級客戶端,傳入低級客戶端
        RestHighLevelClient restHighLevelClient = new RestHighLevelClient(restClient);
        //創建查詢請求對象,提供索引和類型,如果建表時規范的話,可以不提供類型的
        SearchRequest searchRequest = new SearchRequest("索引").types("類型");
        //構建query條件
        QueryBuilder queryBuilder = new MatchAllQueryBuilder();
        //query條件作為查詢條件,size表示返回結果的條數
        SearchSourceBuilder builder = new SearchSourceBuilder().query(queryBuilder).size(10);
        //請求對象攜帶條件,查詢類型,一般默認即可
        searchRequest.source(builder).searchType(SearchType.DEFAULT);
        try {
            //通過高級客戶端執行查詢請求,返回響應對象
            SearchResponse searchResponse = restHighLevelClient.search(searchRequest);
            //拿到響應的匹配結果,遍歷
            for (SearchHit hit : searchResponse.getHits().getHits()) {
                //轉為String,也可以getSourceAsMap轉為map,后續進行操作
                System.out.println(hit.getSourceAsString());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

這里注意:

　　使用elasticsearch-rest-high-level-client執行的是http請求,所以對應的是9200的端口(默認).