elasticsearch初探

Elasticsearch：一个集群性质的Lucene搜索引擎

由于项目须要实现按关键字匹配排序功能，原本想用Lucence的，可是L自己只是一个基础library，实际应用的话目测代码量比较大，小公司实现比较吃力，因此使用了elasticsearch，能够集群便于扩展。初次使用，介绍一下简单的入门，不涉及任何高端技巧，熟悉的朋友不用看了，浪费时间。

项目一直使用的spring-boot-starter，顺便找了一下，果真找到有社区贡献的集成jar，很厚脸皮的直接拿过来用了，项目地址：https://github.com/spring-projects/spring-data-elasticsearch，注意：这里的client版本支持的是1.5.2，官方最新版本已经到2.1了，社区版本目前支持较低，反正我是初学，先学会使用。

开始动手：

1. 添加依赖

<!-- maven -->
<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-elasticsearch</artifactId>
    <version>1.3.0.RELEASE</version>
</dependency>

# gradle
dependencies {
    compile "org.springframework.boot:spring-boot-starter-data-elasticsearch"
}

1. 配置

   <!-- xml -->
   <?xml version="1.0" encoding="UTF-8"?>
   <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:elasticsearch="http://www.springframework.org/schema/data/elasticsearch"
      xsi:schemaLocation="http://www.springframework.org/schema/data/elasticsearch http://www.springframework.org/schema/data/elasticsearch/spring-elasticsearch.xsd
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
   
   <elasticsearch:node-client id="client" local="true"/>
   
   <bean name="elasticsearchTemplate" class="org.springframework.data.elasticsearch.core.ElasticsearchTemplate">
       <constructor-arg name="client" ref="client"/>
   </bean>
   
   </beans>

   注意local="true"，表示client启动在本地，经试验，没有什么实际用途，内存占用严重，里面在集成店别的东西，很容易内存溢出，仅做演示用。Transport Client配置（其实就是链接远程服务）：

   <?xml version="1.0" encoding="UTF-8"?>
   <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:elasticsearch="http://www.springframework.org/schema/data/elasticsearch"
      xsi:schemaLocation="http://www.springframework.org/schema/data/elasticsearch http://www.springframework.org/schema/data/elasticsearch/spring-elasticsearch.xsd
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
   
   <elasticsearch:repositories base-package="com.xyz.acme"/>
   
   <elasticsearch:transport-client id="client" cluster-nodes="ip:9300,ip:9300" cluster-name="elasticsearch" />
   
   <bean name="elasticsearchTemplate" class="org.springframework.data.elasticsearch.core.ElasticsearchTemplate">
       <constructor-arg name="client" ref="client"/>
   </bean>
   </beans>

#java config:
#application.properties：

esearch.host=192.168.199.150
esearch.port=9300

@Configuration
@EnableElasticsearchRepositories(basePackages = "org/aybx/wishes/user/elastic")
public class ElasticSearchConfig {

    @Value("${esearch.port}") int port;
    @Value("${esearch.host}") String hostname;

    @Bean
    public ElasticsearchOperations elasticsearchTemplate() {
        return new ElasticsearchTemplate(client());
    }

    @Bean
    public Client client(){
        TransportClient client= new TransportClient();
        TransportAddress address = new InetSocketTransportAddress(hostname, port);
        client.addTransportAddress(address);
        return client;
    }
}

basePackages包含继承spring-data的Repositories

1. 个人包结构以下：
   

ESUser类须要注解@Document(indexName = "user")，指定id，ES的目录结构大概是/index/type/documentId，ESUserRepository须要继承ElasticsearchCrudRepository，Service是正常的业务代码，测试代码：

@RunWith(value = SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = BootStartup.class)
@WebAppConfiguration
@ActiveProfiles("scratch")
public class ESUserServiceTest {

    private static final Logger LOGGER = LoggerFactory.getLogger(ESUserServiceTest.class);

    @Autowired
    IESUserService iesUserService;

    @Autowired
    private ElasticsearchTemplate elasticsearchTemplate;

    @Test
    public void testSave() throws Exception {
        ESUser user = new ESUser();
        user.setId(1L);
        user.setContent("接机,包房,作饭");

        user = iesUserService.save(user);

        LOGGER.info("user, {}", JSON.toJSONString(user));

        ESUser user1 = new ESUser();
        user1.setId(2L);
        user1.setContent("接机,包房");

        user1 = iesUserService.save(user1);

        LOGGER.info("user1, {}", JSON.toJSONString(user1));

        ESUser user2 = new ESUser();
        user2.setId(3L);
        user2.setContent("包房,作饭");

        user2 = iesUserService.save(user2);

        LOGGER.info("user2, {}", JSON.toJSONString(user2));
    }

    @Test
    public void testFind() throws Exception {
        SearchQuery searchQuery = new NativeSearchQueryBuilder().withQuery(queryStringQuery("接机 OR 作饭")).withFields("content").build();
        List<ESUser> esUsers = elasticsearchTemplate.queryForList(searchQuery, ESUser.class);
        for (ESUser user : esUsers) {
            LOGGER.info("user:{}, content:{}", user.getId(), user.getContent());
        }
    }
}

这里没有用service调用，写了一个简单的查询，接机和作饭中间的OR表示匹配或的意思，还有不少能够操做的地方，详细能够参考官方文档，好比增长一个条件的权重，筛选多余的filed，筛选子类的属性等等；感受复杂到不行，不过也对，搜索的时候必然会有这样的须要，也很符合实际状况。

最后说一下ES的插件用法，好比常见的monitor功能：Marvel，安装，/bin/plugin install elasticsearch/marvel/latest，这是低版本的装法，新版参考文档