Elasticsearch 7：Java REST Client API 客户端

#Elasticsearch

介绍

REST Client 有两个版本，一个是 Low Level，提供了比较简单的 HTTP 客户端功能。具体可参考 https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.2/java-rest-low.html 。

另一个是 High Level Client，基于 Low level Client，做了一些封装，比较好用。具体文档见 https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.2/java-rest-high.html。

本文使用 High Level Client 。

实战1

ES 版本 7.13.4

gradle 依赖：

compile 'org.elasticsearch.client:elasticsearch-rest-high-level-client:7.13.4'

数据准备

# 创建索引
PUT student
{
  "mappings" : {
    "properties" : {
      "uid": {
        "type" : "integer"
      },
      "name" : {
        "type" : "keyword"
      },
      "age" : {
        "type" : "integer"
      }
    }
  },
  "settings" : {
    "index" : {
      "number_of_shards" : 10,
      "number_of_replicas" : 1
    }
  }
}

# 插入数据
POST student/_doc/1?routing=1
{
  "uid": 1,
  "name": "张三",
  "age": 10
}

# 插入数据
POST student/_doc/2?routing=2
{
  "uid": 2,
  "name": "张三",
  "age": 10
}

查询数据：

# 请求
GET student/_search
{
  "query": {
    "match_all": {}
  },
  "explain": true
}

# 结果
{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 10,
    "successful" : 10,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_shard" : "[student][7]",
        "_node" : "gejvpvFJTTK8LAnyvaI3_Q",
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_routing" : "2",
        "_source" : {
          "uid" : 2,
          "name" : "张三",
          "age" : 10
        },
        "_explanation" : {
          "value" : 1.0,
          "description" : "*:*",
          "details" : [ ]
        }
      },
      {
        "_shard" : "[student][8]",
        "_node" : "gejvpvFJTTK8LAnyvaI3_Q",
        "_index" : "student",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_routing" : "1",
        "_source" : {
          "uid" : 1,
          "name" : "张三",
          "age" : 10
        },
        "_explanation" : {
          "value" : 1.0,
          "description" : "*:*",
          "details" : [ ]
        }
      }
    ]
  }
}

查询 _id 为 1 的数据

package esdemo;


import org.apache.http.HttpHost;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;

import java.io.IOException;


public class TestClient {

    public static void main(String[] args) throws IOException {
        RestClientBuilder restClientBuilder = RestClient.builder(
                new HttpHost("localhost", 9200, "http")
        );
        RestHighLevelClient client = new RestHighLevelClient(restClientBuilder);

        GetRequest getRequest = new GetRequest();
        getRequest.index("student");
        getRequest.routing("1");
        getRequest.id("1");

        System.out.println("请求:");
        System.out.println(getRequest);

        GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);

        System.out.println("查询结果:");
        System.out.println(getResponse);

        client.close();
    }
}

执行结果：

get [student][_doc][1]: routing [1]
查询结果:
{"_index":"student","_type":"_doc","_id":"1","_version":1,"_seq_no":0,"_primary_term":1,"_routing":"1","found":true,"_source":{"uid":1,"name":"张三","age":10}}

查询 _id 1 数据的详细信息

package esdemo;


import org.apache.http.HttpHost;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;

import java.io.IOException;


public class TestClient {

    public static void main(String[] args) throws IOException {
        RestClientBuilder restClientBuilder = RestClient.builder(
                new HttpHost("localhost", 9200, "http")
        );
        RestHighLevelClient client = new RestHighLevelClient(restClientBuilder);

        GetRequest getRequest = new GetRequest();
        getRequest.index("student");
        getRequest.routing("1");
        getRequest.id("1");

        System.out.println("请求:");
        System.out.println(getRequest);

        GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);

        System.out.println("索引: " + getResponse.getIndex());
        System.out.println("type: " + getResponse.getType());
        System.out.println("id: " + getResponse.getId());
        System.out.println("source: " + getResponse.getSourceAsString());
        System.out.println("source.name: " + getResponse.getSourceAsMap().get("name"));

        client.close();
    }
}

执行结果：

请求:
get [student][_doc][1]: routing [1]
索引: student
type: _doc
id: 1
source: {"uid":1,"name":"张三","age":10}
source.name: 张三

基于 term 查询，结果有数据

package esdemo;


import org.apache.http.HttpHost;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.builder.SearchSourceBuilder;

import java.io.IOException;


public class TestClient {

    public static void main(String[] args) throws IOException {
        RestClientBuilder restClientBuilder = RestClient.builder(
                new HttpHost("localhost", 9200, "http")
        );
        RestHighLevelClient client = new RestHighLevelClient(restClientBuilder);

        SearchRequest searchRequest = new SearchRequest();
        searchRequest.indices("student");
        searchRequest.allowPartialSearchResults(false);

        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        searchSourceBuilder.timeout(TimeValue.timeValueMillis(1000));
        searchSourceBuilder.query(QueryBuilders.boolQuery().filter(QueryBuilders.termQuery("name", "张三")));
        searchRequest.source(searchSourceBuilder);

        System.out.println("查询语句: ");
        System.out.println(searchSourceBuilder);

        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

        System.out.println("查询结果：");
        System.out.println(searchResponse);

        client.close();
    }
}

执行结果：

查询语句: {
    "timeout": "1000ms",
    "query": {
        "bool": {
            "filter": [
                {
                    "term": {
                        "name": {
                            "value": "张三",
                            "boost": 1.0
                        }
                    }
                }
            ],
            "adjust_pure_negative": true,
            "boost": 1.0
        }
    }
}
查询结果：
{
    "took": 1,
    "timed_out": false,
    "_shards": {
        "total": 10,
        "successful": 10,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 0.0,
        "hits": [
            {
                "_index": "student",
                "_type": "_doc",
                "_id": "2",
                "_score": 0.0,
                "_routing": "2",
                "_source": {
                    "uid": 2,
                    "name": "张三",
                    "age": 10
                }
            },
            {
                "_index": "student",
                "_type": "_doc",
                "_id": "1",
                "_score": 0.0,
                "_routing": "1",
                "_source": {
                    "uid": 1,
                    "name": "张三",
                    "age": 10
                }
            }
        ]
    }
}

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