Elasticsearch Java API 怎么用

Elasticsearch Java API 是 Elasticsearch 提供的 Java 客户端 API，可以通过 Java 代码操作 Elasticsearch。

使用 Elasticsearch Java API 可以进行以下操作：

1. 创建索引
2. 删除索引
3. 添加文档
4. 更新文档
5. 删除文档
6. 查询文档

使用 Elasticsearch Java API 的步骤如下：

1. 添加 Maven 依赖

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>7.14.0</version>
</dependency>

2. 创建客户端

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(new HttpHost("localhost", 9200, "http")));

3. 创建索引

CreateIndexRequest request = new CreateIndexRequest("my_index");
client.indices().create(request, RequestOptions.DEFAULT);

4. 添加文档

IndexRequest request = new IndexRequest("my_index");
Map<String, Object> jsonMap = new HashMap<>();
jsonMap.put("user", "kimchy");
jsonMap.put("postDate", new Date());
jsonMap.put("message", "trying out Elasticsearch");
request.source(jsonMap);
IndexResponse response = client.index(request, RequestOptions.DEFAULT);

5. 查询文档

SearchRequest searchRequest = new SearchRequest("my_index");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchQuery("message", "Elasticsearch"));
searchRequest.source(searchSourceBuilder);
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

6. 关闭客户端

client.close();