Elasticsearch - 尚硅谷（4. Elasticsearch 基本操作_下）学习笔记

Posted 2021-05-17 yuan_404

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文章目录

• 3.5 Java API 操作
• • 3.5.1 搭建环境
  • 3.5.2 创建客户端对象
  • 3.5.3 索引操作
  • 3.5.4 文档操作
  • 3.5.5 高级查询

3.5 Java API 操作

• Elasticsearch 软件是由 Java 语言开发的，所以也可以通过 Java API 的方式对 Elasticsearch
  服务进行访问

3.5.1 搭建环境

1. 在 IDEA 中创建一个 Maven 依赖

2. 修改 Pom.xml

   <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>
   

3.5.2 创建客户端对象

• 新建一个类，并编写代码

  public class ESTest_Client {
      public static void main(String[] args) throws Exception {
          // 创建ES客户端
          RestHighLevelClient esClient = new RestHighLevelClient(
                  RestClient.builder(new HttpHost("localhost", 9200, "http"))
          );
          // 关闭ES客户端
          esClient.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

• 启动测试

  控制台没有报错就表示连接成功

3.5.3 索引操作

• ES 服务器正常启动后，可以通过 Java API 客户端对象对 ES 索引进行操作

1. 创建索引

• 创建新的类，并编写

  public class ESTest_Index_Create {
      public static void main(String[] args) throws Exception {
          RestHighLevelClient esClient = new RestHighLevelClient(
                  RestClient.builder(new HttpHost("localhost", 9200, "http"))
          );
          // 创建索引
          CreateIndexRequest request = new CreateIndexRequest("user");
          CreateIndexResponse createIndexResponse =
                  esClient.indices().create(request, RequestOptions.DEFAULT);
          // 响应状态
          boolean acknowledged = createIndexResponse.isAcknowledged();
          System.out.println("索引操作 ：" + acknowledged);
          esClient.close();
      }
  }
  

• 启动测试
  

2. 查看索引

   // 查询索引
       GetIndexRequest request = new GetIndexRequest("user");
   
       GetIndexResponse getIndexResponse =
               esClient.indices().get(request, RequestOptions.DEFAULT);
       // 响应状态
       System.out.println(getIndexResponse.getAliases());
       System.out.println(getIndexResponse.getMappings());
       System.out.println(getIndexResponse.getSettings());
   

   允许测试
   

3. 删除索引

    // 查询索引
       DeleteIndexRequest request = new DeleteIndexRequest("user");
       AcknowledgedResponse response = esClient.indices().delete(request, RequestOptions.DEFAULT);
       // 响应状态
       System.out.println(response.isAcknowledged());
   
   

   允许测试
   

3.5.4 文档操作

• 创建数据模型

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

1. 新增文档

    // 插入数据
       IndexRequest request = new IndexRequest();
       request.index("user").id("1001");
   
       User user = new User();
       user.setName("zhangsan");
       user.setAge(30);
       user.setSex("男");
   
       // 向ES插入数据，必须将数据转换位JSON格式
       ObjectMapper mapper = new ObjectMapper();
       String userJson = mapper.writeValueAsString(user);
       request.source(userJson, XContentType.JSON);
   
       IndexResponse response = esClient.index(request, RequestOptions.DEFAULT);
   
       System.out.println(response.getResult());
   

   运行测试
   

2. 修改文档

   // 修改数据
       UpdateRequest request = new UpdateRequest();
       request.index("user").id("1001");
       request.doc(XContentType.JSON, "sex", "女");
   
       UpdateResponse response = esClient.update(request, RequestOptions.DEFAULT);
   
       System.out.println(response.getResult());
   

   运行测试
   

3. 查询文档

   // 查询数据
       GetRequest request = new GetRequest();
       request.index("user").id("1001");
       GetResponse response = esClient.get(request, RequestOptions.DEFAULT);
   
       System.out.println(response.getSourceAsString());
   

   运行测试
   

4. 删除文档

   	DeleteRequest request = new DeleteRequest();
       request.index("user").id("1001");
   
       DeleteResponse response = esClient.delete(request, RequestOptions.DEFAULT);
       System.out.println(response.toString());
   

   运行测试
   

5. 批量操作

• 批量新增

  // 批量插入数据
      BulkRequest request = new BulkRequest();
  
      request.add(new IndexRequest().index("user").id("1001").source(XContentType.JSON, "name", "zhangsan", "age",30,"sex","男"));
      request.add(new IndexRequest().index("user").id("1002").source(XContentType.JSON, "name", "lisi", "age",30,"sex","女"));
      request.add(new IndexRequest().index("user").id("1003").source(XContentType.JSON, "name", "wangwu", "age",40,"sex","男"));
  
      BulkResponse response = esClient.bulk(request, RequestOptions.DEFAULT);
      System.out.println(response.getTook());
      System.out.println(response.getItems());
  

  运行测试
  

• 批量删除

  // 批量删除数据
      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"));
  
      BulkResponse response = esClient.bulk(request, RequestOptions.DEFAULT);
      System.out.println(response.getTook());
      System.out.println(response.getItems());
  

  运行测试
  

3.5.5 高级查询

1. 查询所有索引数据

   // 1. 查询索引中全部的数据
       SearchRequest request = new SearchRequest();
       request.indices("user");
       request.source(new SearchSourceBuilder().query(QueryBuilders.matchAllQuery()));
       SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);
       SearchHits hits = response.getHits();
       System.out.println(hits.getTotalHits());
       System.out.println(response.getTook());
       for ( SearchHit hit : hits ) {
           System.out.println(hit.getSourceAsString());
       }
   

   

2. term 查询，查询条件为关键字

   	SearchRequest request = new SearchRequest();
       request.indices("user");
       request.source(new SearchSourceBuilder().query(QueryBuilders.termQuery("age", 30)));
       SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);
       SearchHits hits = response.getHits();
       System.out.println(hits.getTotalHits());
       System.out.println(response.getTook());
       for ( SearchHit hit : hits ) {
           System.out.println(hit.getSourceAsString());
       }
   

   

3. 分页查询

   	SearchRequest request = new SearchRequest();
       request.indices("user");
       SearchSourceBuilder builder = new SearchSourceBuilder().query(QueryBuilders.matchAllQuery());
       // (当前页码-1)*每页显示数据条数
       builder.from(2);
       builder.size(2);
       request.source(builder);
       SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);
       SearchHits hits = response.getHits();
       System.out.println(hits.getTotalHits());
       System.out.println(response.getTook());
       for ( SearchHit hit : hits ) {
           System.out.println(hit.getSourceAsString());
       }
   

   

4. 查询排序

   	SearchRequest request = new SearchRequest();
       request.indices("user");
       SearchSourceBuilder builder = new SearchSourceBuilder().query(QueryBuilders.matchAllQuery());
       builder.sort("age", SortOrder.DESC);
       request.source(builder);
       SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);
       SearchHits hits = response.getHits();
       System.out.println(hits.getTotalHits());
       System.out.println(response.getTook());
       for ( SearchHit hit : hits ) {
           System.out.println(hit.getSourceAsString());
       }
   

   

5. 过滤字段

   	SearchRequest request = new SearchRequest();
       request.indices("user");
       SearchSourceBuilder builder = new SearchSourceBuilder().query(QueryBuilders.matchAllQuery());
       String[] excludes = {"age"};
       String[] includes = {};
       builder.fetchSource(includes, excludes);
       request.source(builder);
       SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);
       SearchHits hits = response.getHits();
       System.out.println(hits.getTotalHits());
       System.out.println(response.getTook());
       for ( SearchHit hit : hits ) {
           System.out.println(hit.getSourceAsString());
       }
   

   

6. 组合查询

   	SearchRequest request = new SearchRequest();
       
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