Elasticsearch 入门(3)：java API 与 ES

JAVA API

创建 Maven 项目

• 在 IDEA 中创建maven项目，再 pom 中引入相关依赖

  <dependencies>
  	 <dependency>
  		 <groupId>org.elasticsearch</groupId>
  		 <artifactId>elasticsearch</artifactId>
  		 <version>7.8.0</version>
  	 </dependency>
  	 <!-- elasticsearch 的客户端 -->
  	 <dependency>
  		 <groupId>org.elasticsearch.client</groupId>
  		 <artifactId>elasticsearch-rest-high-level-client</artifactId>
  		 <version>7.8.0</version>
  	 </dependency>
  	 <!-- elasticsearch 依赖 2.x 的 log4j -->
  	 <dependency>
  		 <groupId>org.apache.logging.log4j</groupId>
  		 <artifactId>log4j-api</artifactId>
  		 <version>2.8.2</version>
  	 </dependency>
  	 <dependency>
  		 <groupId>org.apache.logging.log4j</groupId>
  		 <artifactId>log4j-core</artifactId>
  		 <version>2.8.2</version>
  	</dependency>
  	<dependency>
  		<groupId>com.fasterxml.jackson.core</groupId>
  		<artifactId>jackson-databind</artifactId>
  		<version>2.9.9</version>
  	</dependency>
  	 <!-- junit 单元测试 -->
  	 <dependency>
  		 <groupId>junit</groupId>
  		 <artifactId>junit</artifactId>
  		 <version>4.12</version>
  	 </dependency>
  </dependencies>
  

客户端对象的创建与删除

• 创建 com.atguigu.es.test.Elasticsearch01_Client 类，代码中创建 Elasticsearch 客户端对象

  // 创建客户端对象
  RestHighLevelClient client = new RestHighLevelClient(
  	RestClient.builder(new HttpHost("localhost", 9200, "http"))
  );
  ...
  // 关闭客户端连接
  client.close();
  

• 注意：9200 端口为 Elasticsearch 的 Web 通信端口，localhost 为启动 ES 服务的主机名

索引操作

1、 创建索引

// 创建索引 - 请求对象
CreateIndexRequest request = new CreateIndexRequest("user");
// 发送请求，获取响应
CreateIndexResponse response = client.indices().create(request, 
RequestOptions.DEFAULT);
boolean acknowledged = response.isAcknowledged();
// 响应状态
System.out.println("操作状态 = " + acknowledged);

2、 查看索引

	// 查询索引 - 请求对象
	GetIndexRequest request = new GetIndexRequest("user");
	// 发送请求，获取响应
	GetIndexResponse response = client.indices().get(request, 
	RequestOptions.DEFAULT);
	System.out.println("aliases:"+response.getAliases());
	System.out.println("mappings:"+response.getMappings());
	System.out.println("settings:"+response.getSettings());

3、 删除索引

// 删除索引 - 请求对象
DeleteIndexRequest request = new DeleteIndexRequest("user");
// 发送请求，获取响应
AcknowledgedResponse response = client.indices().delete(request, 
RequestOptions.DEFAULT);
// 操作结果
System.out.println("操作结果 ： " + response.isAcknowledged());

文档操作

1. 新增文档

• 创建数据模型

  class User {
        
         
  	 private String name; 
  	 private Integer age; 
  	 private String sex; 
  	 
  	 public String getName() {
        
         
  		 return name; 
  	 } 
  	 public void setName(String name) 
  		 this.name = name; 
  	 } 
  	 public Integer getAge() {
        
        
  		 return age; 
  	 } 
  	 public void setAge(Integer age) {
        
        
  		 this.age = age; 
  	 } 
  	 public String getSex() {
        
         
  		 return sex; 
  	 } 
  	 public void setSex(String sex) {
        
         
  		 this.sex = sex; 
  	 } 
  } 
  

• 创建数据，添加到文档中

  // 新增文档 - 请求对象
  IndexRequest request = new IndexRequest();
  // 设置索引及唯一性标识
  request.index("user").id("1001");
  // 创建数据对象
  User user = new User();
  user.setName("zhangsan");
  user.setAge(30);
  user.setSex("男");
  //将对象转为json并且与mapper进行对应
  ObjectMapper objectMapper = new ObjectMapper();
  String productJson = objectMapper.writeValueAsString(user);
  // 添加文档数据，数据格式为 JSON 格式
  request.source(productJson,XContentType.JSON);
  // 客户端发送请求，获取响应对象
  IndexResponse response = client.index(request, RequestOptions.DEFAULT);
  3.打印结果信息
  System.out.println("_index:" + response.getIndex());
  System.out.println("_id:" + response.getId());
  System.out.println("_result:" + response.getResult()); 
  

  

2. 查询文档

//1.创建请求对象
GetRequest request = new GetRequest().index("user").id("1001");
//2.客户端发送请求，获取响应对象
GetResponse response = client.get(request, RequestOptions.DEFAULT);
3.打印结果信息
System.out.println("_index:" + response.getIndex());
System.out.println("_type:" + response.getType());
System.out.println("_id:" + response.getId());
System.out.println("source:" + response.getSourceAsString());

3. 修改文档

// 修改文档 - 请求对象
UpdateRequest request = new UpdateRequest();
// 配置修改参数
request.index("user").id("1001");
// 设置请求体，对数据进行修改
request.doc(XContentType.JSON, "sex", "女");
// 客户端发送请求，获取响应对象
UpdateResponse response = client.update(request, RequestOptions.DEFAULT);
System.out.println("_index:" + response.getIndex());
System.out.println("_id:" + response.getId());
System.out.println("_result:" + response.getResult());

4. 删除文档

//创建请求对象
DeleteRequest request = new DeleteRequest().index("user").id("1");
//客户端发送请求，获取响应对象
DeleteResponse response = client.delete(request, RequestOptions.DEFAULT);
//打印信息
System.out.println(response.toString());

批量操作

1. 批量新增

//创建批量新增请求对象
BulkRequest request = new BulkRequest();
//相当于存了一个list，可以多次add
request.add(new IndexRequest().index("user").id("1001").source(XContentType.JSON, "name", 
"zhangsan"));
request.add(new IndexRequest().index("user").id("1002").source(XContentType.JSON, "name", 
"lisi"));
request.add(new IndexRequest().index("user").id("1003").source(XContentType.JSON, "name", 
"wangwu"));
//客户端发送请求，获取响应对象
BulkResponse responses = client.bulk(request, RequestOptions.DEFAULT);
//打印结果信息
System.out.println("took:" + responses.getTook());
System.out.println("items:" + responses.getItems());

2. 批量删除

//创建批量删除请求对象
BulkRequest request = new BulkRequest();
request.add(new DeleteRequest().index("user").id("1001"));
request.add(new DeleteRequest().index("user").id("1002"));
request.add(new DeleteRequest().index("user").id("1003"));
//客户端发送请求，获取响应对象
BulkResponse responses = client.bulk(request, RequestOptions.DEFAULT);
//打印结果信息
System.out.println("took:" + responses.getTook());
System.out.println("items:" + responses.getItems());

高级查询

1. 请求体查询

// 创建搜索请求对象
SearchRequest request = new SearchRequest();
//指定索引为 student
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
// 查询所有数据
sourceBuilder.query(QueryBuilders.matchAllQuery());
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配，hits 即为命中条数
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

2. term 查询，查询条件为关键字

// 创建搜索请求对象
SearchRequest request = new SearchRequest();
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.termQuery("age", "30"));
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

3. 分页查询

/ 创建搜索请求对象
SearchRequest request = new SearchRequest();
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.matchAllQuery());
// 分页查询
// 当前页其实索引(第一条数据的顺序号)，from
sourceBuilder.from(0);
// 每页显示多少条 size
sourceBuilder.size(2);
//指定请求体
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

4. 数据排序

// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.matchAllQuery());
// 排序
sourceBuilder.sort("age", SortOrder.ASC);
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

5. 过滤字段

// 创建搜索请求对象
SearchRequest request = new SearchRequest();
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.matchAllQuery());
//查询字段过滤
String[] excludes = {
    
    };
String[] includes = {
    
    "name", "age"};
sourceBuilder.fetchSource(includes, excludes);
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

6. Bool 查询

// 创建搜索请求对象
SearchRequest request = new SearchRequest();
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
// 必须包含
boolQueryBuilder.must(QueryBuilders.matchQuery("age", "30"));
// 一定不含
boolQueryBuilder.mustNot(QueryBuilders.matchQuery("name", "zhangsan"));
// 可能包含
boolQueryBuilder.should(QueryBuilders.matchQuery("sex", "男"));
sourceBuilder.query(boolQueryBuilder);
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
//输出每条查询的结果信息
System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

7. 范围查询

// 创建搜索请求对象
SearchRequest request = new SearchRequest();
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
RangeQueryBuilder rangeQuery = QueryBuilders.rangeQuery("age");
// 大于等于
rangeQuery.gte("30");
// 小于等于
rangeQuery.lte("40");
sourceBuilder.query(rangeQuery);
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

8. 模糊查询

// 创建搜索请求对象
SearchRequest request = new SearchRequest();
request.indices("student");
// 构建查询的请求体
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.fuzzyQuery("name","zhangsan").fuzziness(Fuzziness.ONE));
request.source(sourceBuilder);
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
// 查询匹配
SearchHits hits = response.getHits();
System.out.println("took:" + response.getTook());
System.out.println("timeout:" + response.isTimedOut());
System.out.println("total:" + hits.getTotalHits());
System.out.println("MaxScore:" + hits.getMaxScore());
System.out.println("hits========>>");
for (SearchHit hit : hits) {
    
    
	//输出每条查询的结果信息
	System.out.println(hit.getSourceAsString());
}
System.out.println("<<========");

9. 高亮查询

// 高亮查询
SearchRequest request = new SearchRequest().indices("student");
//2.创建查询请求体构建器
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
//构建查询方式：高亮查询
TermsQueryBuilder termsQueryBuilder = 
QueryBuilders.termsQuery("name","zhangsan");
//设置查询方式
sourceBuilder.query(termsQueryBuilder);
//构建高亮字段
HighlightBuilder highlightBuilder = new HighlightBuilder();
highlightBuilder.preTags("<font color='red'>");//设置标签前缀
highlightBuilder.postTags("</font>");//设置标签后缀
highlightBuilder.field("name");//设置高亮字段
//设置高亮构建对象
sourceBuilder.highlighter(highlightBuilder);
//设置请求体
request.source(sourceBuilder);
//3.客户端发送请求，获取响应对象
SearchResponse response = client.search(request, RequestOptions.DEFAULT);
//4.打印响应结果
SearchHits hits = response.getHits();
System.out.println("took::"+response.getTook());
System.out.println("time_out::"+response.isTimedOut());
System.out.println("total::"+hits.getTotalHits());
System.out.println("max_score::"+hits.getMaxScore());
System.out.println("hits::::>>");
for (SearchHit hit : hits) {
    
    
String sourceAsString = hit.getSourceAsString();
System.out.println(sourceAsString);
//打印高亮结果
Map<String, HighlightField> highlightFields = hit.getHighlightFields();
	System.out.println(highlightFields);
}
System.out.println("<<::::");

10. 聚合查询

• 最大年龄

  // 高亮查询
  SearchRequest request = new SearchRequest().indices("student");
  SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
  sourceBuilder.aggregation(AggregationBuilders.max("maxAge").field("age"));
  //设置请求体
  request.source(sourceBuilder);
  //3.客户端发送请求，获取响应对象
  SearchResponse response = client.search(request, RequestOptions.DEFAULT);
  //4.打印响应结果
  SearchHits hits = response.getHits();
  System.out.println(response);
  

  

• 分组统计

  // 高亮查询
  SearchRequest request = new SearchRequest().indices("student");
  SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
  sourceBuilder.aggregation(AggregationBuilders.terms("age_groupby").field("age"));
  //设置请求体
  request.source(sourceBuilder);
  //3.客户端发送请求，获取响应对象
  SearchResponse response = client.search(request, RequestOptions.DEFAULT);
  //4.打印响应结果
  SearchHits hits = response.getHits();
  System.out.println(response);