es中ElasticSearchTemplate类的实现原理及使用

曾经终败给现在 2022-08-29 09:54 585阅读 0赞

通过上一篇文章可以知道，JPA中有个ElasticsearchRepository可以做Elasticsearch的相关数据的增删改查，用法和普通的接口是一样的，这样就能统一ElasticSearch和普通的JPA操作，获得和操作mysql一样的代码体验。同时也可以看到ElasticsearchRepository的功能是比较少的，简单查询够用，但复杂查询就稍微显得力不从心了。然而 ElasticsearchTemplate 则提供了更多的方法，同时也包括分页之类的，他其实就是一个封装好的ElasticSearch Util功能类，通过直接连接client来完成数据的操作。下面我们就分析一下其原理和使用。

一、ElasticsearchTemplate 的原理

1、springBoot 的pom文件引入：

<dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
            </dependency>

2、配置文件配置

#如禁止es的健康检查如下，默认均为开启状态
    
    management:
      health:
        elasticsearch:
          enabled: false
    
    es:
      ip: 172.18.80.33
      port: 9200
      articleType: /nandao-article/

3、项目中ElasticsearchTemplate 接口的创建配置：

import javax.annotation.PostConstruct;
    import org.elasticsearch.client.Client;
    import org.springframework.boot.autoconfigure.AutoConfigureBefore;
    import org.springframework.cache.annotation.EnableCaching;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.data.elasticsearch.core.ElasticsearchTemplate;
    import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
    import org.springframework.data.elasticsearch.core.convert.MappingElasticsearchConverter;
    import org.springframework.data.elasticsearch.core.mapping.SimpleElasticsearchMappingContext;
    
    
    @Configuration
    @AutoConfigureBefore(RedisConfig.class)
    @EnableCaching
    public class ElasticConfig {
    
      @PostConstruct
      void init() {
        System.setProperty("es.set.netty.runtime.available.processors", "false");
      }
    
      //启动服务时调用有参构造方法，生成elasticsearchTemplate对象，可以依赖注入到业务类
      @Bean(name = "elasticsearchTemplate")
      public ElasticsearchTemplate elasticsearchTemplate(Client client, ElasticsearchConverter converter) {
        try {
          return new ElasticsearchTemplate(client, converter);
        }
        catch (Exception ex) {
          throw new IllegalStateException(ex);
        }
      }
    
    }

其实源码 中有多种有参构造方法：

3.1、构造方法：

public ElasticsearchTemplate(Client client) {
    		this(client, new MappingElasticsearchConverter(new SimpleElasticsearchMappingContext()));
    	}
    
    	public ElasticsearchTemplate(Client client, EntityMapper entityMapper) {
    		this(client, new MappingElasticsearchConverter(new SimpleElasticsearchMappingContext()), entityMapper);
    	}
    
    	public ElasticsearchTemplate(Client client, ElasticsearchConverter elasticsearchConverter,
    			EntityMapper entityMapper) {
    		this(client, elasticsearchConverter,
    				new DefaultResultMapper(elasticsearchConverter.getMappingContext(), entityMapper));
    	}
    
    	public ElasticsearchTemplate(Client client, ResultsMapper resultsMapper) {
    		this(client, new MappingElasticsearchConverter(new SimpleElasticsearchMappingContext()), resultsMapper);
    	}
    
    	public ElasticsearchTemplate(Client client, ElasticsearchConverter elasticsearchConverter) {
    		this(client, elasticsearchConverter, new DefaultResultMapper(elasticsearchConverter.getMappingContext()));
    	}
    
    	public ElasticsearchTemplate(Client client, ElasticsearchConverter elasticsearchConverter,
    			ResultsMapper resultsMapper) {
    
    		Assert.notNull(client, "Client must not be null!");
    		Assert.notNull(elasticsearchConverter, "ElasticsearchConverter must not be null!");
    		Assert.notNull(resultsMapper, "ResultsMapper must not be null!");
    
    		this.client = client;
    		this.elasticsearchConverter = elasticsearchConverter;
    		this.resultsMapper = resultsMapper;
    	}

3.2、实现关系：

public class ElasticsearchTemplate implements ElasticsearchOperations, ApplicationContextAware {
    
    //省略。。。。
    }

实现两个接口类，类似于工具类。

3.3、初始化参数：

private static final Logger QUERY_LOGGER = LoggerFactory.getLogger("org.springframework.data.elasticsearch.core.QUERY");
    	private static final Logger LOGGER = LoggerFactory.getLogger(ElasticsearchTemplate.class);
    	private static final String FIELD_SCORE = "_score";
    
    	private Client client;
    	private ElasticsearchConverter elasticsearchConverter;
    	private ResultsMapper resultsMapper;
    	private String searchTimeout;

3.4、常用接口：

此类里面有很多实现ElasticsearchOperations后的接口，均是用来处理es数据的，如下图所示：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L25hbmRhbzE1OA_size_16_color_FFFFFF_t_70][]

4、业务上的注入引用，和普通接口一样：

@Resource
        private ElasticsearchTemplate elasticsearchTemplate;

二、ElasticsearchTemplate 中常用接口的使用

1、保存接口：

@PostMapping("saveEs")
        public void saveEs(@Validated @RequestBody ArticleEsDto req){
            ArticleEsDto dto = new ArticleEsDto();
            dto.setTitle(req.getTitle());
            dto.setSummary(req.getSummary());
            dto.setContent(req.getContent());
            dto.setArticleId(999L);
            dto.setId(req.getId());
            dto.setSource(req.getSource());
            dto.setJid(111L);
            dto.setListPicturePath("http:llll");
            //保存的核心代码
            IndexQuery indexQuery = new IndexQueryBuilder().withId(dto.getId()).withObject(dto).build();
            elasticsearchTemplate.index(indexQuery);
            return;
        }

2、查询接口：

@RequestMapping("/singleWord")
        public List<ArticleEsDto> singleTitle(@Validated @RequestBody String mobileType) {
            SearchQuery searchQuery = new NativeSearchQueryBuilder().withQuery(QueryBuilders.queryStringQuery(mobileType)).build();
            List<ArticleEsDto> articleEsDtos = elasticsearchTemplate.queryForList(searchQuery, ArticleEsDto.class);
            return articleEsDtos;
        }

3、查询结果,默认是查询10条数据：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L25hbmRhbzE1OA_size_16_color_FFFFFF_t_70 1][]

到此，ElasticsearchTemplate 接口分析完毕。

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