作者：狮子也疯狂
专栏：《es》
坚持做好每一步，幸运之神自然会驾凌在你的身上

一、🐇前言

大家好！我是狮子，在上几篇文章中，详细介绍了在kibana中操作es，现在我们来看看真实开发中，如何使用Java操作es。

二、🐇原生JAVA操作ES_搭建项目

咱们先来了解一下，原生Java操作ES api接口，但是原生Java操作es的索引和文档太繁琐，我们只需要稍作了解。

Ⅰ、创建项目

我们先来创建一个普通Maven项目，并且引入以下依赖。

<dependencies>
    <dependency>
      <groupId>org.elasticsearch</groupId>
      <artifactId>elasticsearch</artifactId>
      <version>7.17.0</version>
    </dependency>
    <dependency>
      <groupId>org.elasticsearch.client</groupId>
      <artifactId>elasticsearch-resthigh-level-client</artifactId>
      <version>7.17.0</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
    </dependency>
</dependencies>

Ⅱ、索引操作

在原生Java操作es索引的时候，连接es的对象为RestHighLevelClient，其实就五步操作：
1.创建客户端对象，连接ES
2.创建请求对象
3.发送请求
4.操作响应结果
5.关闭客户端

2.1 创建空索引

// 创建空索引
@Test
public void createIndex() throws IOException{
    // 1.创建客户端对象，连接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.0.187", 9200, "http")));
    // 2.创建请求对象
    CreateIndexRequest request = new CreateIndexRequest("student");
    // 3.发送请求
        CreateIndexResponse response = client.indices()
        	.create(request,RequestOptions.DEFAULT);
    // 4.操作响应结果
  	 System.out.println(response.index());
  // 5.关闭客户端
 	 client.close();
}

tips：如果项目初次访问es失败，需要添加外部访问配置
打开Elasticsearch安装路径下config目录下的elasticsearch.yml文件，加入如下配置：

discovery.seed_hosts: ["host1"]
network.host: 0.0.0.0
重新启动ES即可。

2.2 给索引添加结构

@Test
public void mappingIndex() throws IOException {
    // 1.创建客户端对象，连接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.0.187", 9200, "http")));
    // 2.创建请求对象
    PutMappingRequest request = new PutMappingRequest("student");
   			 request.source("{\n" +
                   " \"properties\":{\n" +
                   " \"id\":{\n" +
                   " \"type\":\"integer\"\n" +
                   "   },\n" +
                   " \"name\":{\n" +
                   " \"type\":\"text\"\n" +
                   "   },\n" +
                   " \"age\":{\n" +
                   " \"type\":\"integer\"\n" +
                   "   }\n" +
                   " }\n" +
                   "}", XContentType.JSON);
    // 3.发送请求
      AcknowledgedResponse response = client.indices()
      		.putMapping(request,RequestOptions.DEFAULT);
    // 4.操作响应结果
  		System.out.println(response.isAcknowledged());
    // 5.关闭客户端
    client.close();
}

2.3 删除索引

// 删除索引
@Test
public void deleteIndex() throws IOException{
    // 1.创建客户端对象，连接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    	.builder(new HttpHost("192.168.0.187", 9200, "http")));
    // 2.创建请求对象
    DeleteIndexRequest request = new DeleteIndexRequest("student");
    // 3.发送请求
     AcknowledgedResponse response = client.indices()
     	.delete(request,RequestOptions.DEFAULT);
    // 4.操作响应结果  
	System.out.println(response.isAcknowledged(
));
    // 5.关闭客户端
    client.close();
}

Ⅲ、文档操作

在进行文档操作时，还是老套路，先创建客户端对象，连接es（和前面一样），但是请求对象创建不同，如果是新增或者修改文档，则请求IndexRequest对象，如果是根据id查询，则请求GetRequest,如果是删除，则创建DeleteRequest对象。

3.1 新增&修改文档

@Test
public void addDocument() throws IOException{
    // 1.创建客户端对象，连接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.0.187", 9200, "http")));
    // 2.创建请求对象
    IndexRequest request = new IndexRequest("student").id("1");
  	request.source(XContentFactory.jsonBuilder()
                   .startObject()
                   .field("id", 1)
                   .field("name", "i love conding")
                   .field("age", 20)
                   .endObject());
    // 3.发送请求
    IndexResponse response = client.index(request,RequestOptions.DEFAULT);
    // 4.操作响应结果
    System.out.println(response.status());
    // 5.关闭客户端
    client.close();
}

3.2 根据id查询文档

// 根据id查询文档
@Test
public void findByIdDocument() throws IOException {
    // 1.创建客户端对象，连接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.0.187", 9200, "http")));
    // 2.创建请求对象
    GetRequest request = new GetRequest("student", "1");
    // 3.发送请求
    GetResponse response = client.get(request, RequestOptions.DEFAULT);
    // 4.操作响应结果
	System.out.println(response.getSourceAsString());
    // 5.关闭客户端
    client.close();
}

3.3 删除文档

// 删除文档
@Test
public void DeleteDocument() throws IOException {
    // 1.创建客户端对象，连接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.0.187", 9200, "http")));
    // 2.创建请求对象
    DeleteRequest request = new DeleteRequest("student", "1");
    // 3.发送请求
    DeleteResponse response = client.delete(request,RequestOptions.DEFAULT);
    // 4.操作响应结果
    System.out.println(response.status());
    // 5.关闭客户端
    client.close();
}

Ⅳ、搜索操作

搜索操作是es的最主要的操作，刚开始的两步和前面一样，但是创建请求对象时，创建的是SearchRequest。使用不同的方法来操作索引。

4.1 搜索所有文档

@Test
public void queryAllDocument() throws IOException {
    // 创建客户端对象，链接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.1.58",9200,"http")));
    // 创建搜索条件
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
  	searchSourceBuilder.query(QueryBuilders.matchAllQuery());
    // 创建请求对象
    SearchRequest request = new SearchRequest("student").source(searchSourceBuilder);
    // 发送请求
     SearchResponse response = client.search(request,RequestOptions.DEFAULT);
    // 输出返回结果
    for (SearchHit hit:response.getHits()) {
      System.out.println(hit.getSourceAsString());
   }
    // 关闭客户端
    client.close();
}

4.2 根据关键词搜索文档

@Test
public void queryTermDocument() throws IOException {
    // 创建客户端对象，链接ES
    RestHighLevelClient client = new RestHighLevelClient(RestClient
    		.builder(new HttpHost("192.168.1.58",9200,"http")));
    // 创建请求条件
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(QueryBuilders.termQuery("info","boy"));
    // 创建请求对象
    SearchRequest request = new SearchRequest("student")
    		.source(searchSourceBuilder);
    // 发送请求
    SearchResponse response = client.search(request,RequestOptions.DEFAULT);
    // 输出返回结果
    for (SearchHit hit:response.getHits()) {
      System.out.println(hit.getSourceAsString());
   }
    // 关闭客户端
    client.close();
}