Spring Data Elasticsearch 开发指南

1. 概述

Spring Data Elasticsearch 是 Spring Data 项目的一个重要模块，旨在为 Elasticsearch 提供一套与 Spring 框架无缝集成的解决方案。它简化了与 Elasticsearch 的交互，提升了开发效率，同时保留了 Elasticsearch 的灵活性和强大功能。

2. 创建示例项目

2.1 项目依赖

在 pom.xml 中添加必要的依赖：


   
    
    
     org.springframework.boot
    
    
    
     spring-boot-starter-data-elasticsearch

2.2 应用配置

在 application.yml 中配置 Elasticsearch 连接信息：

spring:
    data:
        elasticsearch:
            cluster-name: elasticsearch
            cluster-nodes: 192.168.56.101:9300

3. 实体类与注解

3.1 实体类定义

定义一个简单的 Item 实体类，并添加必要的注解：

@Entity
@Document(indexName = "item", type = "docs", shards = 1, replicas = 0)
public class Item {
    @Id
    private Long id;
    @Field(type = FieldType.Text, analyzer = "ik_max_word")
    private String title;
    @Field(type = FieldType.Keyword)
    private String category;
    @Field(type = FieldType.Keyword)
    private String brand;
    @Field(type = FieldType.Double)
    private Double price;
    @Field(index = false, type = FieldType.Keyword)
    private String images;
}

3.2 注解说明

@Document：标记实体类为 Elasticsearch 文档对象，配置索引名称、类型等属性。

@Id：标记字段为主键。

@Field：定义字段的映射属性，包括字段类型、索引设置等。

4. Elasticsearch 操作

4.1 创建索引

使用 ElasticsearchTemplate 创建索引并自动映射实体类：

@RunWith(SpringRunner.class)
@SpringBootTest(classes = ItcastElasticsearchApplication.class)
public class IndexTest {
    @Autowired
    private ElasticsearchTemplate elasticsearchTemplate;
    @Test
    public void testCreate() {
        elasticsearchTemplate.createIndex(Item.class);
        elasticsearchTemplate.putMapping(Item.class);
    }
}

4.2 删除索引

@Test
public void deleteIndex() {
    elasticsearchTemplate.deleteIndex("heima");
}

5. Repository 操作

5.1 自动化 Repository

定义一个接口，继承 ElasticsearchRepository：

public interface ItemRepository extends ElasticsearchRepository
   
     {}

5.2 文档操作

5.2.1 新增文档

@Autowired
private ItemRepository itemRepository;
@Test
public void index() {
    Item item = new Item(1L, "小米手机7", "手机", "小米", 3499.00, "http://image.leyou.com/13123.jpg");
    itemRepository.save(item);
}

5.2.2 批量新增

@Test
public void indexList() {
    List
   
     list = new ArrayList<>();
    list.add(new Item(2L, "坚果手机R1", "手机", "锤子", 3699.00, "http://image.leyou.com/13123.jpg"));
    list.add(new Item(3L, "华为META10", "手机", "华为", 4499.00, "http://image.leyou.com/3.jpg"));
    itemRepository.saveAll(list);
}

6. 查询与聚合

6.1 基本查询

6.1.1 全部查询

@Test
public void testFind() {
    Iterable
   
     items = itemRepository.findAll(Sort.by(Sort.Direction.DESC, "price"));
    items.forEach(item -> System.out.println(item));
}

6.1.2 按价格排序

@Test
public void testSort() {
    Page
   
     items = itemRepository.search(
        new NativeSearchQueryBuilder()
            .withQuery(QueryBuilders.termQuery("category", "手机"))
            .withSort(SortBuilders.fieldSort("price").order(SortOrder.DESC))
            .build()
    );
    items.forEach(System.out::println);
}

7. 高级查询

7.1 自定义查询

7.1.1 模糊查询

@Test
public void testNativeQuery() {
    NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder();
    queryBuilder.withQuery(QueryBuilders.matchQuery("title", "小米"));
    Page
   
     items = itemRepository.search(queryBuilder.build());
    System.out.println(items.getTotalElements());
    items.forEach(System.out::println);
}

7.1.2 分页查询

@Test
public void testPageQuery() {
    NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder();
    queryBuilder.withPageable(PageRequest.of(0, 3));
    queryBuilder.withQuery(QueryBuilders.termQuery("category", "手机"));
    Page
   
     items = itemRepository.search(queryBuilder.build());
    System.out.println(items.getTotalElements());
    System.out.println(items.getTotalPages());
    items.forEach(System.out::println);
}

8. 聚合操作

8.1 桶聚合

8.1.1 按品牌分组

@Test
public void testAgg() {
    NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder();
    queryBuilder.withSourceFilter(new FetchSourceFilter(new String[]{""}, null));
    queryBuilder.addAggregation(
        AggregationBuilders.terms("brands").field("brand")
    );
    AggregatedPage
   
     aggPage = itemRepository.search(queryBuilder.build());
    StringTerms agg = (StringTerms) aggPage.getAggregation("brands");
    List
    
      buckets = agg.getBuckets();
    for (StringTerms.Bucket bucket : buckets) {
        System.out.println(bucket.getKeyAsString() + "，共" + bucket.getDocCount() + "台");
    }
}

8.2 嵌套聚合

8.2.1 计算每个品牌的平均价格

@Test
public void testSubAgg() {
    NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder();
    queryBuilder.withSourceFilter(new FetchSourceFilter(new String[]{""}, null));
    queryBuilder.addAggregation(
        AggregationBuilders.terms("brands").field("brand")
            .subAggregation(AggregationBuilders.avg("priceAvg").field("price"))
    );
    AggregatedPage
   
     aggPage = itemRepository.search(queryBuilder.build());
    StringTerms agg = (StringTerms) aggPage.getAggregation("brands");
    List
    
      buckets = agg.getBuckets();
    for (StringTerms.Bucket bucket : buckets) {
        System.out.println(bucket.getKeyAsString() + "，共" + bucket.getDocCount() + "台");
        InternalAvg avg = (InternalAvg) bucket.getAggregations().asMap().get("priceAvg");
        System.out.println("平均售价：" + avg.getValue());
    }
}

以上内容涵盖了 Spring Data Elasticsearch 的核心功能，包括索引操作、文档存储与查询、聚合等高级功能，适合开发者快速入门和实际应用。

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