<think>我们遇到了一个关于
Elasticsearch Java客户端的问题：代码中使用的RestHighLevelClient在较新版本的
Elasticsearch中已被弃用，并在
8.x版本中被移除。因此，我们需要将代码迁移到新的Java客户端API。
### 问题分析
Elasticsearch从
7.15
.0版本开始标记RestHighLevelClient为弃用，并在
8.0版本中完全移除。官方推荐使用新的Java客户端，该客户端具有以下特点：
1
. 与
Elasticsearch服务器版本兼容（当前最新为
8.x）
2
. 更简洁的API设计
3
. 基于Java
8的
函数式编程风格
4
. 支持异步和同步操作
### 解决方案：迁移到新的
Elasticsearch Java客户端
我们将使用
Elasticsearch官方的新Java客户端（`
elasticsearch-java`）重写示例代码。
#### 步骤1：添加Maven依赖
```xml
<dependency>
<groupId>co
.elastic
.clients</groupId>
<artifactId>
elasticsearch-java</artifactId>
<version>
8.12
.2</version>
</dependency>
<!
-- 还需要Jackson依赖进行JSON处理
-->
<dependency>
<groupId>com
.fasterxml
.jackson
.core</groupId>
<artifactId>jackson
-databind</artifactId>
<version>2
.15
.3</version>
</dependency>
```
#### 步骤2：创建客户端
新的客户端使用`RestClient`作为底层HTTP通信，然后构建`
ElasticsearchClient`。
#### 步骤3：重写操作
新客户端的API与之前的RestHighLevelClient有较大不同，需要重新编写索引、搜索等操作。
### 完整代码示例（使用新Java客户端）
```java
import co
.elastic
.clients
.elasticsearch.ElasticsearchClient;
import co
.elastic
.clients
.elasticsearch.core
.*;
import co
.elastic
.clients
.elasticsearch.core
.search
.Hit;
import co
.elastic
.clients
.json
.Json
Data;
import co
.elastic
.clients
.json
.jackson
.JacksonJsonpMapper;
import co
.elastic
.clients
.transport
.ElasticsearchTransport;
import co
.elastic
.clients
.transport
.rest_client
.RestClientTransport;
import org
.apache
.http
.HttpHost;
import org
.apache
.http
.auth
.AuthScope;
import org
.apache
.http
.auth
.UsernamePasswordCredentials;
import org
.apache
.http
.client
.CredentialsProvider;
import org
.apache
.http
.impl
.client
.BasicCredentialsProvider;
import org
.elasticsearch.client
.RestClient;
import java
.io
.IOException;
import java
.util
.Collections;
import java
.util
.List;
public class New
ElasticsearchDemo {
public static void main
(String[] args
) throws IOException {
// 创建客户端
ElasticsearchClient client = createClient
();
// 索引名称和文档ID
String indexName = "new_java_index";
String docId = "1
01";
// 1
. 索引文档
System
.out
.println
("===== 索引文档 ====="
);
Product product = new Product
("Coffee Maker",
89
.99, 15
);
IndexResponse indexResponse = indexDocument
(client, indexName, docId, product
);
System
.out
.println
("索引结果: " + indexResponse
.result
().toString
());
System
.out
.println
("文档ID: " + indexResponse
.id
());
// 2
. 获取文档
System
.out
.println
("\n===== 获取文档 ====="
);
Product getProduct = getDocument
(client, indexName, docId
);
if
(getProduct != null
) {
System
.out
.println
("获取到的产品: " + getProduct
);
} else {
System
.out
.println
("文档不存在"
);
}
// 3
. 搜索文档
System
.out
.println
("\n===== 搜索文档 ====="
);
List<Product> products = searchProducts
(client, indexName, "Coffee"
);
System
.out
.println
("搜索到 " + products
.size
() + " 个产品"
);
for
(Product p : products
) {
System
.out
.println
(p
);
}
// 4
. 更新文档（增加库存）
System
.out
.println
("\n===== 更新文档 ====="
);
updateDocument
(client, indexName, docId, "stock", 2
0);
getProduct = getDocument
(client, indexName, docId
);
System
.out
.println
("更新后的产品: " + getProduct
);
// 5
. 删除文档
System
.out
.println
("\n===== 删除文档 ====="
);
DeleteResponse deleteResponse = deleteDocument
(client, indexName, docId
);
System
.out
.println
("删除结果: " + deleteResponse
.result
().toString
());
getProduct = getDocument
(client, indexName, docId
);
if
(getProduct == null
) {
System
.out
.println
("文档已成功删除"
);
}
client
.shutdown
();
}
// 创建新的
Elasticsearch客户端
private static
ElasticsearchClient createClient
() {
// 配置认证信息（如果需要）
final CredentialsProvider credentialsProvider = new BasicCredentialsProvider
();
credentialsProvider
.setCredentials
(AuthScope
.ANY,
new UsernamePasswordCredentials
("elastic", "password"
)); // 替换为实际凭证
// 创建底层RestClient
RestClient restClient = RestClient
.builder(new HttpHost
("localhost", 92
00))
.setHttpClientConfigCallback
(httpClient
Builder -> httpClient
Builder
.setDefaultCredentialsProvider
(credentialsProvider
))
.build
();
// 使用Jackson映射器创建Transport
ElasticsearchTransport transport = new RestClientTransport
(
restClient,
new JacksonJsonpMapper
()
);
// 创建API客户端
return new
ElasticsearchClient
(transport
);
}
// 索引文档
private static IndexResponse indexDocument
(ElasticsearchClient client, String index, String id, Product product
) throws IOException {
IndexRequest<Product> request = IndexRequest
.of
(b
-> b
.index
(index
)
.id
(id
)
.document
(product
)
);
return client
.index
(request
);
}
// 获取文档
private static Product getDocument
(ElasticsearchClient client, String index, String id
) throws IOException {
GetRequest request = GetRequest
.of
(b
-> b
.index
(index
).id
(id
));
GetResponse<Product> response = client
.get
(request, Product
.class
);
if
(response
.found
()) {
return response
.source
();
} else {
return null;
}
}
// 搜索文档
private static List<Product> searchProducts
(ElasticsearchClient client, String index, String keyword
) throws IOException {
SearchRequest request = SearchRequest
.of
(b
-> b
.index
(index
)
.query
(q
-> q
.match
(m
-> m
.field
("name"
)
.query
(keyword
)
)
)
);
SearchResponse<Product> response = client
.search
(request, Product
.class
);
return response
.hits
().hits
().stream
()
.map
(Hit::source
)
.toList
();
}
// 更新文档（部分更新）
private static void updateDocument
(ElasticsearchClient client, String index, String id, String field, Object value
) throws IOException {
UpdateRequest<Product, Object> request = UpdateRequest
.of
(b
-> b
.index
(index
)
.id
(id
)
.doc
(Collections
.singletonMap
(field, value
))
);
client
.update
(request, Object
.class
);
}
// 删除文档
private static DeleteResponse deleteDocument
(ElasticsearchClient client, String index, String id
) throws IOException {
DeleteRequest request = DeleteRequest
.of
(b
-> b
.index
(index
).id
(id
));
return client
.delete
(request
);
}
// 产品类（用于文档映射）
static class Product {
private String name;
private double price;
private int stock;
public Product
() {
// 无参构造
函数用于反序列化
}
public Product
(String name, double price, int stock
) {
this
.name = name;
this
.price = price;
this
.stock = stock;
}
// getters and setters
public String getName
() { return name; }
public void setName
(String name
) { this
.name = name; }
public double getPrice
() { return price; }
public void setPrice
(double price
) { this
.price = price; }
public int getStock
() { return stock; }
public void setStock
(int stock
) { this
.stock = stock; }
@Override
public String toString
() {
return "Product{" +
"name='" + name + '\'' +
", price=" + price +
", stock=" + stock +
'}';
}
}
}
```
### 代码说明
1
. **客户端创建**：使用新的`
ElasticsearchClient`替代`RestHighLevelClient`。
2
. **文档操作**：
- 索引文档：使用`IndexRequest`构建请求，通过`client
.index
()`发送。
- 获取文档：使用`GetRequest`，并通过指定文档类（如`Product
.class`）进行反序列化。
- 搜索文档：使用`SearchRequest`构建查询，返回的搜索结果可以通过`Hit
.source
()`转换为对象。
- 更新文档：使用`UpdateRequest`进行部分更新（传递一个Map）。
- 删除文档：使用`DeleteRequest`。
3
. **POJO映射**：使用Jackson将JSON文档映射到Java对象（`Product`类），需要无参构造
函数和getter/setter。
### 迁移注意事项
1
. **版本兼容性**：确保客户端版本与
Elasticsearch服务器版本一致（主版本号相同）。
2
. **异常处理**：新API可能会抛出`
ElasticsearchException`，需要适当处理。
3
. **异步操作**：新客户端支持异步操作（如`client
.indexAsync
()`），可提高性能。
### 在线运行说明
此代码可以在支持Java
8+和Maven的在线环境中运行（如Replit）。需要设置正确的
Elasticsearch服务器地址和认证信息。
---
§§
相关问题§§:
1
. 如何在新的
Elasticsearch Java客户端中执行批量操作（Bulk）？
2
. 使用新客户端时如何处理连接池和重试策略？
3
. 如何配置新客户端的SSL/TLS加密连接？
4
. 在新客户端中如何实现
聚合查询（
Aggregations）？</think>### 解决
Elasticsearch RestHighLevelClient 弃用问题
Elasticsearch 在
8.0 版本中移除了 `RestHighLevelClient`，改用新的 Java API 客户端。以下是完全兼容
Elasticsearch 8.x 的解决方案：
#### 完整解决方案代码
```java
import co
.elastic
.clients
.elasticsearch.ElasticsearchClient;
import co
.elastic
.clients
.elasticsearch.core
.*;
import co
.elastic
.clients
.elasticsearch.core
.search
.Hit;
import co
.elastic
.clients
.json
.Json
Data;
import co
.elastic
.clients
.json
.jackson
.JacksonJsonpMapper;
import co
.elastic
.clients
.transport
.ElasticsearchTransport;
import co
.elastic
.clients
.transport
.rest_client
.RestClientTransport;
import org
.apache
.http
.HttpHost;
import org
.apache
.http
.auth
.AuthScope;
import org
.apache
.http
.auth
.UsernamePasswordCredentials;
import org
.apache
.http
.client
.CredentialsProvider;
import org
.apache
.http
.impl
.client
.BasicCredentialsProvider;
import org
.elasticsearch.client
.RestClient;
import java
.io
.IOException;
import java
.util
.List;
import java
.util
.Map;
public class
ElasticsearchJavaClientV
8 {
public static void main
(String[] args
) {
// 1
. 创建客户端
try
(ElasticsearchClient client = createClient
()) {
String indexName = "java_products";
String docId = "p1
001";
// 2
. 创建索引文档
System
.out
.println
("===== 创建文档 ====="
);
Map<String, Object> product = Map
.of
(
"name", "Java Programming Book",
"price", 49
.99,
"stock", 1
00,
"tags", List
.of
("java", "programming", "book"
)
);
indexDocument
(client, indexName, docId, product
);
// 3
. 获取文档
System
.out
.println
("\n===== 获取文档 ====="
);
getDocument
(client, indexName, docId
);
// 4
. 搜索文档
System
.out
.println
("\n===== 搜索文档 ====="
);
searchDocuments
(client, indexName, "java"
);
// 5
. 更新文档
System
.out
.println
("\n===== 更新文档 ====="
);
updateDocument
(client, indexName, docId, "stock", 95
);
getDocument
(client, indexName, docId
); // 验证更新
// 6
. 删除文档
System
.out
.println
("\n===== 删除文档 ====="
);
deleteDocument
(client, indexName, docId
);
getDocument
(client, indexName, docId
); // 验证删除
} catch
(Exception e
) {
e
.printStackTrace
();
}
}
// 创建
Elasticsearch 8.x 客户端
private static
ElasticsearchClient createClient
() {
// 配置认证信息
final CredentialsProvider credentialsProvider = new BasicCredentialsProvider
();
credentialsProvider
.setCredentials
(AuthScope
.ANY,
new UsernamePasswordCredentials
("elastic", "your_password"
)); // 替换为实际凭证
// 创建底层 REST 客户端
RestClient restClient = RestClient
.builder(
new HttpHost
("localhost", 92
00))
.setHttpClientConfigCallback
(httpClient
Builder ->
httpClient
Builder.setDefaultCredentialsProvider
(credentialsProvider
))
.build
();
// 使用 Jackson 映射器创建传输层
ElasticsearchTransport transport = new RestClientTransport
(
restClient, new JacksonJsonpMapper
());
return new
ElasticsearchClient
(transport
);
}
// 索引文档
private static void indexDocument
(ElasticsearchClient client, String index, String id, Map<String, Object> source
)
throws IOException {
IndexRequest<Map<String, Object>> request = IndexRequest
.of
(b
-> b
.index
(index
)
.id
(id
)
.document
(source
)
);
IndexResponse response = client
.index
(request
);
System
.out
.println
("结果: " + response
.result
());
System
.out
.println
("文档ID: " + response
.id
());
}
// 获取文档
private static void getDocument
(ElasticsearchClient client, String index, String id
)
throws IOException {
GetRequest request = GetRequest
.of
(b
-> b
.index
(index
)
.id
(id
)
);
GetResponse<Map> response = client
.get
(request, Map
.class
);
if
(response
.found
()) {
System
.out
.println
("文档内容: " + response
.source
());
System
.out
.println
("版本: " + response
.version
());
} else {
System
.out
.println
("文档不存在"
);
}
}
// 搜索文档
private static void searchDocuments
(ElasticsearchClient client, String index, String query
)
throws IOException {
SearchRequest request = SearchRequest
.of
(b
-> b
.index
(index
)
.query
(q
-> q
.match
(m
-> m
.field
("name"
)
.query
(query
)
)
)
);
SearchResponse<Map> response = client
.search
(request, Map
.class
);
System
.out
.println
("命中数量: " + response
.hits
().total
().value
());
for
(Hit<Map> hit : response
.hits
().hits
()) {
System
.out
.println
("ID: " + hit
.id
() + " | 分数: " + hit
.score
());
System
.out
.println
("内容: " + hit
.source
());
}
}
// 更新文档
private static void updateDocument
(ElasticsearchClient client, String index, String id, String field, Object value
)
throws IOException {
UpdateRequest<Map, Object> request = UpdateRequest
.of
(b
-> b
.index
(index
)
.id
(id
)
.doc
(Map
.of
(field, value
))
);
UpdateResponse<Map> response = client
.update
(request, Map
.class
);
System
.out
.println
("结果: " + response
.result
());
System
.out
.println
("新版本: " + response
.version
());
}
// 删除文档
private static void deleteDocument
(ElasticsearchClient client, String index, String id
)
throws IOException {
DeleteRequest request = DeleteRequest
.of
(b
-> b
.index
(index
)
.id
(id
)
);
DeleteResponse response = client
.delete
(request
);
System
.out
.println
("结果: " + response
.result
());
}
}
```
### 迁移说明和关键变化
#### 1
. 客户端创建方式变化
```java
// 旧方式
(已弃用
)
RestHighLevelClient client = new RestHighLevelClient
(
RestClient
.builder(new HttpHost
("localhost", 92
00)));
// 新方式
RestClient restClient = RestClient
.builder(new HttpHost
("localhost", 92
00)).build
();
ElasticsearchTransport transport = new RestClientTransport
(restClient, new JacksonJsonpMapper
());
ElasticsearchClient client = new
ElasticsearchClient
(transport
);
```
#### 2
. API 设计变化
- **强类型 DSL**：使用
builder 模式创建请求
- **
函数式风格**：通过 lambda 表达式配置请求参数
- **响应对象简化**：直接返回操作结果而非 HTTP 状态
#### 3
. Maven 依赖变更
```xml
<dependencies>
<!
-- Elasticsearch Java API 客户端
-->
<dependency>
<groupId>co
.elastic
.clients</groupId>
<artifactId>
elasticsearch-java</artifactId>
<version>
8.12
.2</version>
</dependency>
<!
-- 底层 REST 客户端
-->
<dependency>
<groupId>org
.elasticsearch.client</groupId>
<artifactId>
elasticsearch-rest
-client</artifactId>
<version>
8.12
.2</version>
</dependency>
<!
-- JSON 处理
-->
<dependency>
<groupId>com
.fasterxml
.jackson
.core</groupId>
<artifactId>jackson
-databind</artifactId>
<version>2
.15
.3</version>
</dependency>
</dependencies>
```
### 新旧 API 对比表
| 操作 | 旧 API
(RestHighLevelClient
) | 新 API
(ElasticsearchClient
) |
|
------|
-----------------------------|
------------------------------|
| **创建客户端** | `new RestHighLevelClient
(...)` | 通过 `RestClientTransport` 创建 |
| **索引文档** | `IndexRequest` + `client
.index
()` | `IndexRequest
.of
(b
-> b
...)` |
| **获取文档** | `GetRequest` + `client
.get
()` | `GetRequest
.of
(b
-> b
...)` |
| **搜索文档** | `SearchRequest` + `SearchSource
Builder` | DSL
builder + lambda 表达式 |
| **更新文档** | `UpdateRequest` + `client
.update
()` | `UpdateRequest
.of
(b
-> b
...)` |
| **删除文档** | `DeleteRequest` + `client
.delete
()` | `DeleteRequest
.of
(b
-> b
...)` |
| **响应处理** | 手动解析 JSON/Map | 自动反序列化为 POJO 或 Map |
### 常见迁移问题解决
#### 问题1：依赖冲突
**解决方案**：排除旧依赖
```xml
<dependency>
<groupId>org
.elasticsearch.client</groupId>
<artifactId>
elasticsearch-rest
-high
-level
-client</artifactId>
<version>
7.1
7.3</version>
<exclusions>
<exclusion>
<groupId>org
.elasticsearch</groupId>
<artifactId>
elasticsearch</artifactId>
</exclusion>
</exclusions>
</dependency>
```
#### 问题2：认证配置
**解决方案**：使用 `CredentialsProvider`
```java
CredentialsProvider credsProvider = new BasicCredentialsProvider
();
credsProvider
.setCredentials
(
AuthScope
.ANY,
new UsernamePasswordCredentials
("user", "password"
)
);
RestClient restClient = RestClient
.builder(new HttpHost
("host", 92
00))
.setHttpClientConfigCallback
(hcb
->
hcb
.setDefaultCredentialsProvider
(credsProvider
))
.build
();
```
#### 问题3：SSL/TLS 配置
**解决方案**：配置 SSL 上下文
```java
SSLContext sslContext = SSLContext
Builder.create
()
.loadTrustMaterial
(new TrustSelfSignedStrategy
())
.build
();
RestClient restClient = RestClient
.builder(new HttpHost
("host", 92
00, "https"
))
.setHttpClientConfigCallback
(hcb
->
hcb
.setSSLContext
(sslContext
))
.build
();
```
### 在线测试说明
此代码可直接在支持 Java 1
7+ 的环境中运行：
1
. 确保
Elasticsearch 8.x 服务运行
2
. 更新 `createClient
()` 中的连接信息
3
. 添加上述 Maven 依赖
4
. 运行程序查看完整文档生命周期操作
---
本文详细介绍了Elasticsearch 7.x-8.0中桶聚合的使用，包括filter聚合对结果进行条件过滤，filters聚合实现多条件桶过滤，adjacencyMatrix聚合形成邻接矩阵，sampler聚合对高得分文档采样，以及diversifiedSampler聚合确保样本多样性的功能。通过实例展示了各聚合在大数据分析中的应用场景和效果。
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