Java实战场景下的ElasticSearch

前言

ES官方提供了各种不同语言的客户端，用来操作ES。这些客户端的本质就是组装DSL语句，通过http请求发送给ES，其中的Java Rest Client又包括两种：

• Java Low Level Rest Client
• Java High Level Rest Client

本文介绍的是Java HighLevel Rest Client客户端API；

一、环境准备

在elasticsearch提供的API中，与elasticsearch一切交互都封装在一个名为RestHighLevelClient的类
中，必须先完成这个对象的初始化，建立与elasticsearch的连接。
1）引入es的RestHighLevelClient依赖：

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

2）初始化RestHighLevelClient：
这里为了单元测试方便，我们创建一个测试类HotelIndexTest，然后将初始化的代码编写在
@BeforeEach方法中：

/**
 * @author 杨树林
 * @version 1.0
 * @since 12/8/2023
 */
 @SpringBootTest
class HotelIndexTest{
    private RestHighLevelClient client;
    @BeforeEach
    void setUp(){
        this.client=new RestHighLevelClient(RestClient.builder
                (HttpHost.create("http://localhost:9200")));
    }
    @AfterEach
    void tearDown() throws IOException {
        this.client.close();
    }
 }

3）创建HotelConstants类，定义mapping映射的JSON字符串常量

public class HotelConstants {
    public static final String MAPPING_TEMPLATE = "{\n" +
            "  \"mappings\": {\n" +
            "    \"properties\": {\n" +
            "      \"id\": {\n" +
            "        \"type\": \"keyword\"\n" +
            "      },\n" +
            "      \"name\":{\n" +
            "        \"type\": \"text\",\n" +
            "        \"analyzer\": \"ik_max_word\",\n" +
            "        \"copy_to\": \"all\"\n" +
            "      },\n" +
            "      \"address\":{\n" +
            "        \"type\": \"keyword\",\n" +
            "        \"index\": false\n" +
            "      },\n" +
            "      \"price\":{\n" +
            "        \"type\": \"integer\"\n" +
            "      },\n" +
            "      \"score\":{\n" +
            "        \"type\": \"integer\"\n" +
            "      },\n" +
            "      \"brand\":{\n" +
            "        \"type\": \"keyword\",\n" +
            "        \"copy_to\": \"all\"\n" +
            "      },\n" +
            "      \"city\":{\n" +
            "        \"type\": \"keyword\",\n" +
            "        \"copy_to\": \"all\"\n" +
            "      },\n" +
            "      \"starName\":{\n" +
            "        \"type\": \"keyword\"\n" +
            "      },\n" +
            "      \"business\":{\n" +
            "        \"type\": \"keyword\"\n" +
            "      },\n" +
            "      \"location\":{\n" +
            "        \"type\": \"geo_point\"\n" +
            "      },\n" +
            "      \"pic\":{\n" +
            "        \"type\": \"keyword\",\n" +
            "        \"index\": false\n" +
            "      },\n" +
            "      \"all\":{\n" +
            "        \"type\": \"text\",\n" +
            "        \"analyzer\": \"ik_max_word\"\n" +
            "      }\n" +
            "    }\n" +
            "  }\n" +
            "}";
}

二、RsetAPI操作索引库

编写单元测试，实现一下功能：

1.创建索引库

	@Test
	void creatHotelIndex() throws IOException {
	   //1、创建Requset对象
	   CreateIndexRequest request = new CreateIndexRequest("hotels");
	   //2、准备请求的参数：DEL语句
	   request.source(HotelConstants.MAPPING_TEMPLATE, XContentType.JSON);
	   //3、发起请求
	   client.indices().create(request,RequestOptions.DEFAULT);
	}

2.判断索引库是否存在

	@Test
    void testExistsHotelIndex() throws IOException {
        //1、创建Requset对象
        GetIndexRequest  request = new GetIndexRequest("hotels");
        //2、发起请求
        boolean isExists = client.indices().exists(request,RequestOptions.DEFAULT);

        System.err.println(isExists ? "索引库已经存在！" : "索引库不存在！");
    }

3.删除索引库

	@Test
    void delHotelIndex() throws IOException {
        //1、创建Requset对象
        DeleteIndexRequest request = new DeleteIndexRequest("hotels");
        //2、发起请求
        client.indices().delete(request,RequestOptions.DEFAULT);
    }

二、RsetAPI操作文档

1.新增文档

	@Autowired
    HotelServiceImpl service;
    @Test
    void addDocument() throws IOException {
        // 1.根据id查询酒店数据
        Hotel hotel = service.getById("36934");
        // 2.转换为文档类型
        HotelDoc hotelDoc = new HotelDoc(hotel);
        // 3.将HotelDoc转json
        String json = JSON.toJSONString(hotelDoc);
        IndexRequest request = new IndexRequest("hotels").id(hotelDoc.getId().toString());
        request.source(json, XContentType.JSON);
        client.index(request, RequestOptions.DEFAULT);
    }

2.单条查询

    @Test
    void getDocument() throws IOException {
        GetRequest request = new GetRequest("hotels","36934");

        GetResponse response =  client.get(request, RequestOptions.DEFAULT);

        String json = response.getSourceAsString();

        HotelDoc hotelDoc = JSON.parseObject(json,HotelDoc.class);
        System.out.println(hotelDoc);
    }

3.删除文档

    @Test
    void delDocument() throws IOException {
        DeleteRequest request  = new DeleteRequest("hotels","36934");
        client.delete(request,RequestOptions.DEFAULT);
    }

4.增量修改

api中全局修改与新增一致

    @Test
    void UpdateDocument() throws IOException {
        UpdateRequest request = new UpdateRequest("hotels", "36934");
        request.doc(
                "name","XX酒店",
                "city","西安",
                "price", "200000",
                "starName", "八星级"
        );
        client.update(request, RequestOptions.DEFAULT);
    }

5.批量导入

 	@Test
    void addBulkRequest() throws IOException {
        //查询所有酒店信息
        List<Hotel> hotels = service.list();
        //1.创建request
        BulkRequest request = new BulkRequest();
        for (Hotel hotel : hotels) {
            HotelDoc hotelDoc = new HotelDoc(hotel);
            request.add(new IndexRequest("hotels")
                    .id(hotelDoc.getId().toString())
                    .source(JSON.toJSONString(hotelDoc),XContentType.JSON));
        }
        client.bulk(request,RequestOptions.DEFAULT);
    }

6.自定义响应解析方法

void show(SearchResponse response){
        //解析响应
        SearchHits searchHits =response.getHits();
        //获取总条数
        Long total = searchHits.getTotalHits().value;
        System.out.println("共搜到"+total+"条数据");
        //文档数组
        SearchHit[] hits = searchHits.getHits();
        for (SearchHit hit : hits) {
            String json = hit.getSourceAsString();
            System.err.println(json);
            HotelDoc hotelDoc = JSON.parseObject(json,HotelDoc.class);
            System.out.println(hotelDoc);
        }
    }

四、常用的查询方法

1.MatchAll():查询所有

	@Test
    void testMatchAll() throws IOException {
        //1.准备request
        SearchRequest request = new SearchRequest("hotels");
        //2、准备DEl,QueryBuilders构造查询条件
        request.source().query(QueryBuilders.matchAllQuery());
        //3.执行查询，返回响应结果
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        //4.解析响应
        show(response);
    }

2.matchQuery():单字段查询

	@Test
    void testMatch() throws IOException {
        //1.准备request
        SearchRequest request = new SearchRequest("hotels");
        // 2.准备DSL 参数1：字段  参数2：数据
        request.source().query(QueryBuilders.matchQuery("all","如家"));
        //3.执行查询，返回响应结果
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        //4.解析响应
        show(response);
    }

3.multiMatchQuery()：多字段查询

	@Test
    void testMultiMatch() throws IOException {
        //1.准备request
        SearchRequest request = new SearchRequest("hotels");
        // 2.准备DSL
        request.source().query(QueryBuilders.multiMatchQuery("如家","name","business"));
        //3.执行查询，返回响应结果
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        //4.解析响应
        show(response);
    }

4.termQuery():词条精确值查询

@Test
    void testTermQuery() throws IOException {
        //1.准备request
        SearchRequest request = new SearchRequest("hotels");
        // 2.准备DSL
        request.source().query(QueryBuilders.termQuery("city","上海"));
        //3.执行查询，返回响应结果
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        //4.解析响应
        show(response);
    }

5.rangeQuery():范围查询

	@Test
    void testRangeQuery() throws IOException {
        //1.准备request
        SearchRequest request = new SearchRequest("hotels");
        // 2.准备DSL
        request.source().query(QueryBuilders.rangeQuery("pirce").gte(100).lte(200));
        //3.执行查询，返回响应结果
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        //4.解析响应
        show(response);
    }

6.bool复合查询

布尔查询是一个或多个查询子句的组合,子查询的组合方式有:
must:必须匹配每个子查询，类似“与”;
should:选择性匹配子查询，类似“或”;
must_not:必须不匹配，不参与算分，类似“非”;
filter:必须匹配，类似“与”，不参与算分一般搜索框用must，选择条件使用filter;文章来源地址https://www.toymoban.com/news/detail-679821.html

@Test
    void testBool() throws IOException {
        SearchRequest request = new SearchRequest("hotels");
        //方式1
//        BoolQueryBuilder boolQuery = new BoolQueryBuilder();
//        boolQuery.must(QueryBuilders.termQuery("city","上海"));
//        boolQuery.filter(QueryBuilders.rangeQuery("price").gte(100).lte(200));
//        request.source().query(boolQuery);
        //方式2
        request.source().query(new BoolQueryBuilder()
                .must(QueryBuilders.termQuery("city","上海"))
                .filter(QueryBuilders.rangeQuery("price").gte(100).lte(200)));
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);

        show(response);
    }

7.分页查询

	 @Test
    void testPageAndSort() throws IOException {
        int page = 1, size = 5;
        String searchName = "如家";
        SearchRequest request = new SearchRequest("hotels");
        // 2.1.query
        if(searchName == null){
            request.source().query(QueryBuilders.matchAllQuery());
        }else{
            request.source().query(QueryBuilders.matchQuery("name", searchName));
        }
        // 2.2.分页 from、size
        request.source().from((page - 1) * size).size(size);
        //2.3.排序
        request.source().sort("price", SortOrder.DESC);
        SearchResponse response = client.search(request, RequestOptions.DEFAULT);
        show(response);
    }

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