1. Overview

• Spring Data ElasticSearch simplifies native ElasticSearch
• Characteristic:
  • 1. Based on the @ Configuration configuration, as long as it is configured in the yml file, it can be used in the project.
  • 1. Tool class ElasticsearchTemplate ES template, similar to general mapper, operates ES through object
  • 1. Provides a Repository for the persistence layer interface, which is equivalent to using mapper

Comparison between elastic search and traditional database

Basic concepts

2. Setting up the environment

• Create a sub module and learn elastic search

• Step 1: modify pom.xml file and add corresponding coordinates. Add dependency for ES

  <dependencies>
          <!--redis-->
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-data-redis</artifactId>
          </dependency>
          <dependency>
              <groupId>redis.clients</groupId>
              <artifactId>jedis</artifactId>
          </dependency>
          <!--test-->
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-test</artifactId>
          </dependency>
          <!--custom common-->
          <dependency>
              <groupId>com.czxy</groupId>
              <artifactId>changgou3_common</artifactId>
              <version>1.0-SNAPSHOT</version>
          </dependency>
          <!--es-->
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
          </dependency>
  
      </dependencies>
  

• Step 2: modify the yml file and add the relevant configuration of elastic search

   spring:
    redis:
      database:   1     #Confirm to use the library
      host: 127.0.0.1   #redis service address
      port: 6379      #redis port number
    data:
      elasticsearch:
        cluster-name: elasticsearch
        cluster-nodes: 127.0.0.1:9300
  

• Step 3: add configuration class

package com.czxy.config;

import org.springframework.context.annotation.Configuration;

import javax.annotation.PostConstruct;

/**
 * @author Cloud before court
 * @Date 2020/4/13 20:38
 * @description
 */
@Configuration
public class ESConfig {
    @PostConstruct
    public void init(){
        System.setProperty("es.set.netty.runtime.available.processors","false");
    }
}

3. Index operation

3.1 mapping class

• Mapping class: used to represent the data correspondence between java and elastic search. Using annotations in spring data elastic search.

  Annotated name	describe
  @Document	Used to configure the correspondence between Java class and index / type < br / > - indexname: corresponding index library name < br / > - type: corresponding type in index library < br / > - shards: partition quantity, default 5 < br / > - replicas: Replica quantity, default 1
  @Id	Unique identification
  @Field	Used to configure the field correspondence between Java attributes and es < br > – type: field type, enumeration: fieldtype < br > – analyzer: participator name < br > – index: index, boolean type, default is true < br > – store: store, boolean type, default is false

• Realization

package com.czxy.vo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;
import org.springframework.data.elasticsearch.annotations.FieldType;

/**
 * @author Cloud before court
 * @Date 2020/4/13 20:40
 * @description
 */
@Document(indexName = "czxy56",type = "book",shards = 4,replicas = 2)
@Data
@NoArgsConstructor
@AllArgsConstructor
public class ESBook {
    @Id
    private Long id;

    @Field(type= FieldType.Text, analyzer = "ik_max_word")
    private String title;//Title

    @Field(type=FieldType.Keyword , index = true)
    private String images;//picture

    @Field(type=FieldType.Float)
    private Float price;//Price
}

3.2 create index, add mapping and delete index

• The ElasticsearchTemplate tool class provides corresponding methods to complete the following functions:

  • Create index: createindex (mapping class. class)
  • Add mapping: putmapping (mapping class. class)
  • Delete index: deleteindex (mapping class. class)

• 1, In the test class, inject ElasticsearchTemplate

• 2, Call the corresponding API for operation

  package com.czxy.elasticsearch;
  
  import com.czxy.TestApplication;
  import com.czxy.vo.ESBook;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.springframework.boot.test.context.SpringBootTest;
  import org.springframework.data.elasticsearch.core.ElasticsearchTemplate;
  import org.springframework.test.context.junit4.SpringRunner;
  
  import javax.annotation.Resource;
  
  /**
   * @author Cloud before court
   * @Date 2020/4/13 20:33
   * @description
   */
  @RunWith(SpringRunner.class)
  @SpringBootTest(classes = TestApplication.class)
  public class TestES {
  
      @Resource
      private ElasticsearchTemplate elasticsearchTemplate;
  
  
      @Test
      public void demo01() {
          //Create the index according to the @ Document annotation information of class czxy56
          elasticsearchTemplate.createIndex(ESBook.class);
      }
  
      @Test
      public void demo02() {
          //The configuration mapping will be automatically completed according to the id, Field and other fields in the czxy56 class
          elasticsearchTemplate.putMapping(ESBook.class);
      }
  
      @Test
      public void demo03() {
          //Delete the map, which can be deleted according to the class name or index name
          elasticsearchTemplate.deleteIndex(ESBook.class);
      }
  }
  
  

4. Document operation (addition, deletion and modification)

4.1. Top level interface: Repository

• Spring data elastic search provides a top-level interface Repository. You don't need to write any DAO processing, and automatically CRUD operations based on the method name or class information. As long as you define an interface and then inherit some sub interfaces provided by Repository, you can have various basic crud functions.

  • PagingAndSortingRepository: (second generation) complete paging and sorting functions
  • ElasticsearchCrudRepository: (the third generation) add, delete, modify and query function
  • Elastic search Repository: (fourth generation) complete all functions

• Write: just write sub interface, inherit ElasticsearchRepository, and Spring Data will load the class automatically.

• Note: when using the interface, you need to determine two generic information
  • First generic: mapping class, here is ESBook
  • The second generic type: the type uniquely identified by the mapping class, the type Long of the ID

package com.czxy.Repository;

import com.czxy.vo.ESBook;
import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;

import java.util.List;

/**
 * @author Cloud before court
 * @Date 2020/4/13 20:49
 * @description
 */
public interface ESBookRepository extends ElasticsearchRepository<ESBook, Long> {

}

4.2 add data

package com.czxy.elasticsearch;

import com.czxy.Repository.ESBookRepository;
import com.czxy.TestApplication;
import com.czxy.vo.ESBook;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;
import java.util.ArrayList;

/**
 * @author Cloud before court
 * @Date 2020/4/13 20:51
 * @description
 */
@RunWith(SpringRunner.class)
@SpringBootTest(classes = TestApplication.class)
public class TestData {

    @Resource
    private ESBookRepository esBookRepository;

    @Test
    public void demo01() {
        ESBook esBook = new ESBook(1L, "Test one", "1.jpg", 998f);
        //Add to
        esBookRepository.save(esBook);
    }

    @Test
    public void demo02() {
        ArrayList<ESBook> esBooks = new ArrayList<>();
        esBooks.add(new ESBook(2L, "Test two", "2.jpg", 456f));
        esBooks.add(new ESBook(3L, "Test three", "3.jpg", 290f));
        esBooks.add(new ESBook(4L, "Test four", "4.jpg", 100f));
        //Add a set of data  
        esBookRepository.saveAll(esBooks);
    }
}

4.3 modify data

• Modify and add using the same method

• Differentiation criteria:

  • If the value of id has corresponding data, update is performed.
  • If the value of id does not have corresponding data, add.

      @Test
      public void demo03() {
          //Update data. There must be data with id=1 in es
          ESBook esBook = new ESBook(1L, "Test change", "1111.jpg", 1998f);
          esBookRepository.save(esBook);
      }
  

4.3 delete data

  @Test
    public void demo04() {
        ESBook esBook = new ESBook();
        esBook.setId(1L);
        esBookRepository.delete(esBook);
    }

4.4, query

package com.czxy.elasticsearch;

import com.czxy.Repository.ESBookRepository;
import com.czxy.TestApplication;
import com.czxy.vo.ESBook;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;

/**
 * @author Cloud before court
 * @Date 2020/4/13 21:01
 * @description
 */
@RunWith(SpringRunner.class)
@SpringBootTest(classes = TestApplication.class)
public class TestESFind {
    @Resource
    private ESBookRepository esBookRepository;

    @Test
    public void demo01() {
        //Query all
        Iterable<ESBook> iterable = esBookRepository.findAll();
        Iterator<ESBook> iterator = iterable.iterator();
        while (iterator.hasNext()) {
            ESBook esBook = iterator.next();
            System.out.println(esBook);
        }
    }

    @Test
    public void demo02() {
        //Query details by id
        Optional<ESBook> optional = esBookRepository.findById(2L);
        ESBook esBook = optional.get();
        System.out.println(esBook);
    }
}

• The Optional class is Java8 to solve the problem of null value judgment
• JDK8 features (self study): https://www.jianshu.com/nb/27231419

4.5 user defined method query

• Custom query: Spring Data queries automatically according to the agreed method name.
  • Contract method name requirements: findBy field name | keyword, etc
  • For example: findbytitle (value) queries by title

• Example 1: query by title

  • 1. Modify response custom interface and add method declaration

    package com.czxy.Repository;
    
    import com.czxy.vo.ESBook;
    import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;
    
    import java.util.List;
    
    /**
     * @author Cloud before court
     * @Date 2020/4/13 20:49
     * @description
     */
    public interface ESBookRepository extends ElasticsearchRepository<ESBook, Long> {
        //Example 1: query by title
        public List<ESBook> findByTitle(String title);
    }
    
    

  • 1. Call custom method to complete function

        @Test
        public void demo03() {
            List<ESBook> list = esBookRepository.findByTitle("Test two");
            System.out.println(list);
        }
    

• Example 2: interval query, price 50-300

  • 1. statement

         //Example 2: interval query, price 50-300
        public List<ESBook> findByPriceBetween(Float start, Float end);
    

  • 1. call

        @Test
        public void demo04() {
            List<ESBook> list = esBookRepository.findByPriceBetween(50f, 300f);
            System.out.println(list);
        }
    

• Example 3: query price > = 290

  • 1. statement

        //Example 3: query price > = 290
        public List<ESBook> findByPriceGreaterThanEqual(Float price);
    
    

  • 1. call

        @Test
        public void demo05(){
            List<ESBook> list = esBookRepository.findByPriceGreaterThanEqual(290f);
            System.out.println(list);
        }
    

• Example 4: interval query, price 50-300, and sorting by images in descending order

  • 1. statement

    //Example 4: interval query, price 50-300, and sorted in descending order by image 
    public List<ESBook> findByPriceBetweenOrderByImagesDesc(Float start, Float end);
    
    

  • 1. call

        @Test
        public void demo06(){
            List<ESBook> list = esBookRepository.findByPriceBetweenOrderByImagesDesc(50f,300f);
            System.out.println(list);
        }