ES详细使用！Elasticsearch实现索引操作，增删改查，批处理

要想知道ES怎么具体实现对数据的操作，我们首先应该了解一下什么叫做restful编码风格，因为es的具体操作都是restful风格的。

1.RESTful风格

RESTful 是一种软件架构风格，用于创建可扩展的网络服务。它使用 HTTP 方法（如 GET、POST、PUT、DELETE）来执行 CRUD 操作（创建、读取、更新、删除）。RESTful API 通常具有以下特征：

资源导向：所有内容都是资源，每个资源都有唯一的 URI。
无状态：每个请求都是独立的，服务器不存储客户端的状态。
使用标准方法：使用 HTTP 动词来表示操作。
可缓存：响应可以被客户端缓存以提高性能。

import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.elasticsearch.core.*;
import co.elastic.clients.transport.rest_client.RestClientTransport;
import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.springframework.web.bind.annotation.*;

import java.util.Map;

@RestController
@RequestMapping("/api/documents")
public class DocumentController {

    private final ElasticsearchClient client;

    public DocumentController() {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        this.client = new ElasticsearchClient(transport);
    }

    @PostMapping("/{indexName}/{docId}")
    public String addDocument(@PathVariable String indexName, @PathVariable String docId, @RequestBody Map<String, Object> document) throws Exception {
        client.index(i -> i.index(indexName).id(docId).document(document));
        return "Document added.";
    }

    @GetMapping("/{indexName}/{docId}")
    public Map<String, Object> getDocument(@PathVariable String indexName, @PathVariable String docId) throws Exception {
        GetResponse<Map<String, Object>> response = client.get(g -> g.index(indexName).id(docId), Map.class);
        return response.source();
    }

    @DeleteMapping("/{indexName}/{docId}")
    public String deleteDocument(@PathVariable String indexName, @PathVariable String docId) throws Exception {
        client.delete(d -> d.index(indexName).id(docId));
        return "Document deleted.";
    }
}

URI 设计：API 路径如 /api/documents/{indexName}/{docId} 用于操作特定索引和文档。
HTTP 方法：使用 @PostMapping、@GetMapping、@DeleteMapping 分别处理创建、读取和删除操作。
依赖注入：通过构造函数创建 Elasticsearch 客户端实例。

2.ES的具体操作

2.1添加具体依赖

在pom.xml里面添加下面的依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>co.elastic.clients</groupId>
    <artifactId>elasticsearch-java</artifactId>
    <version>8.4.0</version>
</dependency>

2.2控制器代码

import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.elasticsearch.core.*;
import co.elastic.clients.elasticsearch.core.bulk.*;
import co.elastic.clients.elasticsearch.indices.*;
import co.elastic.clients.transport.rest_client.RestClientTransport;
import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/api")
public class ElasticsearchController {

    private final ElasticsearchClient client;

    public ElasticsearchController() {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        this.client = new ElasticsearchClient(transport);
    }

    // 创建索引
    @PostMapping("/index/{indexName}")
    public String createIndex(@PathVariable String indexName) throws Exception {
        CreateIndexResponse response = client.indices().create(c -> c.index(indexName));
        return response.acknowledged() ? "Index created." : "Index creation failed.";
    }

    // 删除索引
    @DeleteMapping("/index/{indexName}")
    public String deleteIndex(@PathVariable String indexName) throws Exception {
        DeleteIndexResponse response = client.indices().delete(d -> d.index(indexName));
        return response.acknowledged() ? "Index deleted." : "Index deletion failed.";
    }

    // 添加文档
    @PostMapping("/document/{indexName}/{docId}")
    public String addDocument(@PathVariable String indexName, @PathVariable String docId, @RequestBody Map<String, Object> document) throws Exception {
        client.index(i -> i.index(indexName).id(docId).document(document));
        return "Document added.";
    }

    // 获取文档
    @GetMapping("/document/{indexName}/{docId}")
    public Map<String, Object> getDocument(@PathVariable String indexName, @PathVariable String docId) throws Exception {
        GetResponse<Map<String, Object>> response = client.get(g -> g.index(indexName).id(docId), Map.class);
        return response.source();
    }

    // 删除文档
    @DeleteMapping("/document/{indexName}/{docId}")
    public String deleteDocument(@PathVariable String indexName, @PathVariable String docId) throws Exception {
        client.delete(d -> d.index(indexName).id(docId));
        return "Document deleted.";
    }

    // 批量插入文档
    @PostMapping("/bulk/{indexName}")
    public String bulkInsert(@PathVariable String indexName, @RequestBody List<Map<String, Object>> documents) throws Exception {
        BulkRequest.Builder br = new BulkRequest.Builder();

        for (int i = 0; i < documents.size(); i++) {
            br.operations(op -> op.index(idx -> idx.index(indexName).id(String.valueOf(i)).document(documents.get(i))));
        }

        BulkResponse result = client.bulk(br.build());
        return result.errors() ? "Bulk insert had errors." : "Bulk insert completed.";
    }
}

2.2.1控制器类

@RestController
@RequestMapping("/api")
public class ElasticsearchController {

@RestController：标记这个类为一个 RESTful 控制器。
@RequestMapping("/api")：为所有方法定义基础路径 /api。

2.2.2Elasticsearch 客户端初始化

private final ElasticsearchClient client;

public ElasticsearchController() {
    RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
    RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
    this.client = new ElasticsearchClient(transport);
}

创建一个 ElasticsearchClient 实例，用于与 Elasticsearch 通信。

连接到本地运行的 Elasticsearch 实例（localhost:9200）。这里的localhost可以修改成服务器地址

2.2.3创建索引

@PostMapping("/index/{indexName}")
public String createIndex(@PathVariable String indexName) throws Exception {
    CreateIndexResponse response = client.indices().create(c -> c.index(indexName));
    return response.acknowledged() ? "Index created." : "Index creation failed.";
}

@PostMapping("/index/{indexName}")：处理 POST 请求，路径中包含索引名称。

使用 client.indices().create() 创建索引。

返回创建结果。

2.2.4删除索引

@DeleteMapping("/index/{indexName}")
public String deleteIndex(@PathVariable String indexName) throws Exception {
    DeleteIndexResponse response = client.indices().delete(d -> d.index(indexName));
    return response.acknowledged() ? "Index deleted." : "Index deletion failed.";
}

@DeleteMapping("/index/{indexName}")：处理 DELETE 请求，路径中包含索引名称。

使用 client.indices().delete() 删除索引。

返回删除结果。

2.2.5添加文档

@PostMapping("/document/{indexName}/{docId}")
public String addDocument(@PathVariable String indexName, @PathVariable String docId, @RequestBody Map<String, Object> document) throws Exception {
    client.index(i -> i.index(indexName).id(docId).document(document));
    return "Document added.";
}

@PostMapping("/document/{indexName}/{docId}")：处理 POST 请求，包含索引名称和文档 ID。

@RequestBody Map<String, Object> document：从请求体中获取文档内容。

使用 client.index() 添加文档。

2.2.6获取文档

@GetMapping("/document/{indexName}/{docId}")
public Map<String, Object> getDocument(@PathVariable String indexName, @PathVariable String docId) throws Exception {
    GetResponse<Map<String, Object>> response = client.get(g -> g.index(indexName).id(docId), Map.class);
    return response.source();
}

@GetMapping("/document/{indexName}/{docId}")：处理 GET 请求，路径中包含索引名称和文档 ID。

使用 client.get() 获取文档，返回文档内容。

2.2.7删除文档

@DeleteMapping("/document/{indexName}/{docId}")
public String deleteDocument(@PathVariable String indexName, @PathVariable String docId) throws Exception {
    client.delete(d -> d.index(indexName).id(docId));
    return "Document deleted.";
}

@DeleteMapping("/document/{indexName}/{docId}")：处理 DELETE 请求，路径中包含索引名称和文档 ID。

使用 client.delete() 删除文档。

2.2.8批量插入文档

@PostMapping("/bulk/{indexName}")
public String bulkInsert(@PathVariable String indexName, @RequestBody List<Map<String, Object>> documents) throws Exception {
    BulkRequest.Builder br = new BulkRequest.Builder();

    for (int i = 0; i < documents.size(); i++) {
        br.operations(op -> op.index(idx -> idx.index(indexName).id(String.valueOf(i)).document(documents.get(i))));
    }

    BulkResponse result = client.bulk(br.build());
    return result.errors() ? "Bulk insert had errors." : "Bulk insert completed.";
}

@PostMapping("/bulk/{indexName}")：处理 POST 请求，路径中包含索引名称。

@RequestBody List<Map<String, Object>> documents：从请求体中获取多个文档。

使用 BulkRequest.Builder 进行批量操作。

返回批量插入结果。

2.3启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ElasticsearchApplication {

    public static void main(String[] args) {
        SpringApplication.run(ElasticsearchApplication.class, args);
    }
}