es数据库连接，es数据库使用教程

本文目录导读：

1. ES数据库简介
2. ES数据库连接
3. ES数据库的基本操作
4. ES数据库的高级特性

《ES数据库使用全攻略：从连接到高效操作》

ES数据库简介

Elasticsearch（ES）是一个分布式、开源的搜索和分析引擎，适用于各种数据类型，包括文本、数字、地理空间、结构化和非结构化数据等，它以其强大的搜索功能、可扩展性和高可用性在现代数据处理领域中占据着重要地位。

ES数据库连接

（一）安装与启动ES

1、安装

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- 首先根据操作系统类型下载相应的Elasticsearch安装包，对于Linux系统，可以从官方网站下载.tar.gz格式的安装包，以CentOS为例，下载完成后，解压安装包到指定目录，如/usr/local/elasticsearch。

- 在Windows系统中，下载.zip格式的安装包，解压到合适的文件夹。

2、启动

- 在Linux系统中，进入Elasticsearch的bin目录，执行./elasticsearch命令来启动ES服务，需要注意的是，如果是初次启动，可能需要调整系统的一些参数，如文件描述符数量、虚拟内存等，以确保ES能够正常运行。

- 在Windows系统中，执行bin\elasticsearch.bat命令启动服务。

（二）连接ES的客户端

1、使用Java客户端连接（以Java High - Level REST Client为例）

添加依赖：在Java项目中，需要在pom.xml（如果是Maven项目）中添加Elasticsearch客户端的依赖。

```xml

<dependency>

<groupId>org.elasticsearch.client</groupId>

<artifactId>elasticsearch - rest - high - level - client</artifactId>

<version>7.14.0</version>

</dependency>

```

连接代码示例：

```java

import org.elasticsearch.client.RestHighLevelClient;

import org.elasticsearch.client.RestClient;

import java.io.IOException;

public class ESConnection {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

try {

// 这里可以进行一些简单的操作，如检查ES是否可连接

System.out.println(client.ping());

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

2、使用Python客户端连接（以elasticsearch - python为例）

安装：使用pip install elasticsearch命令安装Python的Elasticsearch客户端。

连接代码示例：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

if es.ping():

print('ES连接成功')

else:

print('ES连接失败')

```

ES数据库的基本操作

（一）索引操作

1、创建索引

- 在ES中，索引类似于传统数据库中的表，使用Java客户端创建索引的示例如下：

```java

import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;

import org.elasticsearch.action.admin.indices.create.CreateIndexResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import java.io.IOException;

public class IndexCreation {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

CreateIndexRequest request = new CreateIndexRequest("my_index");

try {

CreateIndexResponse response = client.indices().create(request, RequestOptions.DEFAULT);

if (response.isAcknowledged()) {

System.out.println("索引创建成功");

} else {

System.out.println("索引创建失败");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 使用Python客户端创建索引：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

index_name = "my_index"

body = {

"settings": {

"number_of_shards": 1,

"number_of_replicas": 0

}

}

response = es.indices.create(index = index_name, body = body)

if 'acknowledged' in response and response['acknowledged']:

print('索引创建成功')

else:

print('索引创建失败')

```

2、查看索引

- 在Java中，可以使用IndicesClient来查看已存在的索引：

```java

import org.elasticsearch.client.IndicesClient;

import org.elasticsearch.client.RestHighLevelClient;

import org.elasticsearch.cluster.metadata.IndexMetadata;

import java.io.IOException;

import java.util.Map;

public class IndexView {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

IndicesClient indicesClient = client.indices();

try {

Map<String, IndexMetadata> indexMap = indicesClient.getMetadata("", RequestOptions.DEFAULT);

for (String index : indexMap.keySet()) {

System.out.println("索引名称: " + index);

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中，使用es.indices.get_alias()方法可以查看索引：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

indices = es.indices.get_alias('*')

for index in indices.keys():

print('索引名称:', index)

```

3、删除索引

- 对于Java客户端，如下是删除索引的代码：

```java

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import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;

import org.elasticsearch.action.admin.indices.delete.DeleteIndexResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import java.io.IOException;

public class IndexDeletion {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

DeleteIndexRequest request = new DeleteIndexRequest("my_index");

try {

DeleteIndexResponse response = client.indices().delete(request, RequestOptions.DEFAULT);

if (response.isAcknowledged()) {

System.out.println("索引删除成功");

} else {

System.out.println("索引删除失败");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中，使用es.indices.delete()方法来删除索引：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

index_name = "my_index"

response = es.indices.delete(index = index_name)

if 'acknowledged' in response and response['acknowledged']:

print('索引删除成功')

else:

print('索引删除失败')

```

（二）文档操作

1、插入文档

- 在Java中，向索引中插入文档的示例：

```java

import org.elasticsearch.action.index.IndexRequest;

import org.elasticsearch.action.index.IndexResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import org.elasticsearch.common.xcontent.XContentType;

import java.io.IOException;

import java.util.HashMap;

import java.util.Map;

public class DocumentInsertion {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

Map<String, Object> data = new HashMap<>();

data.put("name", "John Doe");

data.put("age", 30);

data.put("city", "New York");

IndexRequest request = new IndexRequest("my_index").id("1").source(data, XContentType.JSON);

try {

IndexResponse response = client.index(request, RequestOptions.DEFAULT);

if (response.getResult() == DocWriteResponse.Result.CREATED) {

System.out.println("文档插入成功");

} else {

System.out.println("文档插入失败");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中，向索引插入文档：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

doc = {

"name": "John Doe",

"age": 30,

"city": "New York"

}

res = es.index(index = "my_index", id = "1", body = doc)

if res['result'] == 'created':

print('文档插入成功')

else:

print('文档插入失败')

```

2、查询文档

简单查询（根据ID查询）

- 在Java中：

```java

import org.elasticsearch.action.get.GetRequest;

import org.elasticsearch.action.get.GetResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import java.io.IOException;

public class DocumentQueryById {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

GetRequest request = new GetRequest("my_index", "1");

try {

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

if (response.isExists()) {

System.out.println("文档内容: " + response.getSourceAsString());

} else {

System.out.println("文档不存在");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

res = es.get(index = "my_index", id = "1")

if 'found' in res and res['found']:

print('文档内容:', res['_source'])

else:

print('文档不存在')

```

复杂查询（使用查询语句查询）

- 在Java中，使用SearchRequest进行复杂查询，查询年龄大于25岁的人员：

```java

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import org.elasticsearch.action.search.SearchRequest;

import org.elasticsearch.action.search.SearchResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import org.elasticsearch.index.query.QueryBuilders;

import org.elasticsearch.search.SearchHit;

import org.elasticsearch.search.builder.SearchSourceBuilder;

import java.io.IOException;

public class ComplexDocumentQuery {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

SearchRequest request = new SearchRequest("my_index");

SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();

sourceBuilder.query(QueryBuilders.rangeQuery("age").gt(25));

request.source(sourceBuilder);

try {

SearchResponse response = client.search(request, RequestOptions.DEFAULT);

for (SearchHit hit : response.getHits()) {

System.out.println("查询结果: " + hit.getSourceAsString());

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中，同样可以构建查询语句进行复杂查询：

```python

from elasticsearch import Elasticsearch

from elasticsearch_dsl import Search

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

s = Search(using = es, index = "my_index").query("range", age = {"gt": 25})

response = s.execute()

for hit in response:

print('查询结果:', hit.to_dict())

```

3、更新文档

- 在Java中，更新文档的示例：

```java

import org.elasticsearch.action.update.UpdateRequest;

import org.elasticsearch.action.update.UpdateResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import org.elasticsearch.common.xcontent.XContentType;

import java.io.IOException;

public class DocumentUpdate {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

UpdateRequest request = new UpdateRequest("my_index", "1").doc(XContentType.JSON, "age", 31);

try {

UpdateResponse response = client.update(request, RequestOptions.DEFAULT);

if (response.getResult() == DocWriteResponse.Result.UPDATED) {

System.out.println("文档更新成功");

} else {

System.out.println("文档更新失败");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

doc = {

"doc": {

"age": 31

}

}

res = es.update(index = "my_index", id = "1", body = doc)

if res['result'] == 'updated':

print('文档更新成功')

else:

print('文档更新失败')

```

4、删除文档

- 在Java中：

```java

import org.elasticsearch.action.delete.DeleteRequest;

import org.elasticsearch.action.delete.DeleteResponse;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestHighLevelClient;

import java.io.IOException;

public class DocumentDeletion {

public static void main(String[] args) {

RestHighLevelClient client = new RestHighLevelClient(

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

DeleteRequest request = new DeleteRequest("my_index", "1");

try {

DeleteResponse response = client.delete(request, RequestOptions.DEFAULT);

if (response.getResult() == DocWriteResponse.Result.DELETED) {

System.out.println("文档删除成功");

} else {

System.out.println("文档删除失败");

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

client.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

```

- 在Python中：

```python

from elasticsearch import Elasticsearch

es = Elasticsearch([{'host': 'localhost', 'port': 9200}])

res = es.delete(index = "my_index", id = "1")

if res['result'] == 'deleted':

print('文档删除成功')

else:

print('文档删除失败')

```

ES数据库的高级特性

（一）数据映射（Mapping）

1、概念

- 数据映射定义了文档中字段的类型、如何被索引以及如何被存储等信息，它类似于传统数据库中的表结构定义，但更加灵活，在ES中，有动态映射和显式映射两种方式。

2、动态映射示例

- 当向ES索引插入文档时，如果索引不存在映射，ES会根据文档中的数据自动创建映射，插入一个包含name（字符串类型）和`

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