在web网站的架设中特别是数据量大的网站或者APP小程序需要搜索或者全文检索的场景，几乎都需要借助ElasticSearch来作为全文检索引擎，以提高网站的搜索效率和性能。

这一节，我们通过一篇文章介绍，使大家通过一文就学会使用ElasticSearch。

一、ElasticSearch介绍：

ElasticSearch是一个基于Lucene的搜索服务器。它提供了一个分布式多用户能力的全文搜索引擎，基于RESTful web接口。Elasticsearch是用Java开发的，并作为Apache许可条款下的开放源码发布，是当前流行的企业级搜索引擎。设计用于云计算中，能够达到实时搜索，稳定，可靠，快速，安装使用方便。

ElasticSearch相关概念：

a）、索引index，相当于数据库中的database。
b）、类型type相当于数据库中的table。
c）、主键id相当于数据库中记录的主键，是唯一的。
d）、文档 document （相当于一条数据）
文档是ElasticSearch的基本单位。在Es中文档以JSON格式来表示
向es中的index下面的type中存储json类型的数据。
e) 、字段是文档中的field 属性，需要对每一个属性定义索引和被搜索的方式

二、ElasticSearch的安装：

1、先安装jdk

2、安装ElasticSearch

直接进入elasticsearch的官网，下载最新的安装包：https://www.elastic.co/downloads/elasticsearch，此教程使用的是5.1.1版本。

将下载的安装包上传到centos，或者直接在centos使用wget命令下载。

解压：

unzip elasticsearch-5.1.1.zip

运行：

cd bin
./elasticsearch

三、java语言操作ElasticSearch：

1、maven依赖

        org.elasticsearchelasticsearch7.6.2org.elasticsearch.clientelasticsearch-rest-high-level-client7.6.2

2、连接ElasticSearch

import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;import java.io.IOException;public class EsClientTest {public static void main(String[] args) throws IOException {RestHighLevelClient esClient = new RestHighLevelClient(RestClient.builder(new HttpHost("IP",9200,"http")));System.out.println("success");esClient.close();}}

 3、连接的相关api

    public static RestHighLevelClient esClient;static {esClient = new RestHighLevelClient(RestClient.builder(new HttpHost("IP", 9200, "http")));}

4、创建索引操作：

    /*** 创建索引* @throws IOException*/public static void createIndex() throws IOException {CreateIndexRequest createIndexRequest = new CreateIndexRequest("user");CreateIndexResponse indexResponse = esClient.indices().create(createIndexRequest, RequestOptions.DEFAULT);boolean acknowledged = indexResponse.isAcknowledged();System.out.println("索引创建状态:" + acknowledged);}

5、获取索引：

/*** 索引信息查询* @throws IOException*/public static void getIndex() throws IOException {GetIndexRequest getIndexRequest = new GetIndexRequest("user");GetIndexResponse getIndexResponse = esClient.indices().get(getIndexRequest, RequestOptions.DEFAULT);System.out.println(getIndexResponse.getAliases());System.out.println(getIndexResponse.getMappings());System.out.println(getIndexResponse.getSettings());}

6、删除索引：

    /*** 删除索引* @throws IOException*/public static void deleteIndex() throws IOException {DeleteIndexRequest getIndexRequest = new DeleteIndexRequest("user");AcknowledgedResponse delete = esClient.indices().delete(getIndexRequest, RequestOptions.DEFAULT);System.out.println("索引删除状态:" + delete.isAcknowledged());}

7、添加数据：

    /*** 添加数据* @throws Exception*/public static void add() throws Exception{IndexRequest indexRequest = new IndexRequest();indexRequest.index("user").id("1008");User user = new User();user.setName("茅河野人");user.setAge(28);user.setSex("男");user.setSalary(50000);String userData = objectMapper.writeValueAsString(user);indexRequest.source(userData,XContentType.JSON);//插入数据IndexResponse response = esClient.index(indexRequest, RequestOptions.DEFAULT);System.out.println(response.status());System.out.println(response.getResult());}

8、修改数据：

    /*** 修改数据* @throws Exception*/public static void update() throws Exception{UpdateRequest request = new UpdateRequest();request.index("user").id("1008");request.doc(XContentType.JSON,"name","茅河野人");//插入数据UpdateResponse response = esClient.update(request, RequestOptions.DEFAULT);System.out.println(response.getResult());}

9、删除数据：

    /*** 删除* @throws Exception*/public static void delete() throws Exception{DeleteRequest request = new DeleteRequest();request.index("user").id("1008");//插入数据DeleteResponse delete = esClient.delete(request, RequestOptions.DEFAULT);System.out.println(delete.getResult());}

10、批量添加数据：

    /*** 批量添加* @throws Exception*/public static void batchInsert() throws Exception{BulkRequest bulkRequest = new BulkRequest();User user1 = new User("关羽","男",33,5500);String userData1 = objectMapper.writeValueAsString(user1);IndexRequest indexRequest1 = new IndexRequest().index("user").id("1002").source(userData1, XContentType.JSON);bulkRequest.add(indexRequest1);User user2 = new User("黄忠","男",50,8000);String userData2 = objectMapper.writeValueAsString(user2);IndexRequest indexRequest2 = new IndexRequest().index("user").id("1003").source(userData2, XContentType.JSON);bulkRequest.add(indexRequest2);User user3 = new User("黄忠2","男",49,10000);String userData3 = objectMapper.writeValueAsString(user3);IndexRequest indexRequest3 = new IndexRequest().index("user").id("1004").source(userData3, XContentType.JSON);bulkRequest.add(indexRequest3);User user4 = new User("赵云","男",33,12000);String userData4 = objectMapper.writeValueAsString(user4);IndexRequest indexRequest4 = new IndexRequest().index("user").id("1005").source(userData4, XContentType.JSON);bulkRequest.add(indexRequest4);User user5 = new User("马超","男",38,20000);String userData5 = objectMapper.writeValueAsString(user5);IndexRequest indexRequest5 = new IndexRequest().index("user").id("1006").source(userData5, XContentType.JSON);bulkRequest.add(indexRequest5);User user6 = new User("关羽","男",41,27000);String userData6 = objectMapper.writeValueAsString(user6);IndexRequest indexRequest6 = new IndexRequest().index("user").id("1007").source(userData6, XContentType.JSON);bulkRequest.add(indexRequest6);BulkResponse bulkResponse = esClient.bulk(bulkRequest, RequestOptions.DEFAULT);System.out.println(bulkResponse.status());System.out.println(bulkResponse.getItems());}

11、批量删除数据：

    /*** 批量删除* @throws Exception*/public static void batchDelete() throws Exception{BulkRequest bulkRequest = new BulkRequest();DeleteRequest indexRequest1 = new DeleteRequest().index("user").id("1002");DeleteRequest indexRequest2 = new DeleteRequest().index("user").id("1003");DeleteRequest indexRequest3 = new DeleteRequest().index("user").id("1004");DeleteRequest indexRequest4 = new DeleteRequest().index("user").id("1005");DeleteRequest indexRequest5 = new DeleteRequest().index("user").id("1006");DeleteRequest indexRequest6 = new DeleteRequest().index("user").id("1007");bulkRequest.add(indexRequest1);bulkRequest.add(indexRequest2);bulkRequest.add(indexRequest3);bulkRequest.add(indexRequest4);bulkRequest.add(indexRequest5);bulkRequest.add(indexRequest6);BulkResponse bulkResponse = esClient.bulk(bulkRequest, RequestOptions.DEFAULT);System.out.println(bulkResponse.status());System.out.println(bulkResponse.getItems());}

13、删除某个索引下所有数据：

    /*** 查询某个索引下的所有数据* @throws Exception*/public static void searchIndexAll() throws Exception{SearchRequest request = new SearchRequest();request.indices("user");// 索引中的全部数据查询SearchSourceBuilder query = new SearchSourceBuilder().query(QueryBuilders.matchAllQuery());request.source(query);SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);SearchHits hits = response.getHits();for (SearchHit searchHit : hits){System.out.println(searchHit.getSourceAsString());}}

 14、根据条件查询：

        TermQueryBuilder ageQueryBuilder = QueryBuilders.termQuery("sex", "女");SearchSourceBuilder query = new SearchSourceBuilder().query(ageQueryBuilder);request.source(query);SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);System.out.println(response.getHits().getHits());System.out.println(response.getHits().getTotalHits());SearchHits hits = response.getHits();for (SearchHit searchHit : hits){System.out.println(searchHit.getSourceAsString());}

15、分页查询：

        SearchSourceBuilder sourceBuilder = new                         SearchSourceBuilder().query(QueryBuilders.matchAllQuery());sourceBuilder.from(0).size(3);request.source(sourceBuilder);SearchResponse response = esClient.search(request, RequestOptions.DEFAULT);System.out.println(response.getHits().getHits());System.out.println(response.getHits().getTotalHits());SearchHits hits = response.getHits();for (SearchHit searchHit : hits){System.out.println(searchHit.getSourceAsString());}

四、在springboot中的运用

1、maven依赖

     org.springframework.bootspring-boot-starter-data-elasticsearch

2、yml配置文件：

# es 服务地址
elasticsearch.host=IP
# es 服务端口
elasticsearch.port=9200
# 配置日志级别,开启 debug 日志
logging.level.com.congge=debug

3、实际例子：

创建一个实体类

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
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;@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
@Document(indexName = "shopping", shards = 3, replicas = 1)
public class Product {//必须有 id,这里的 id 是全局唯一的标识，等同于 es 中的"_id"@Idprivate Long id;//商品唯一标识/*** type : 字段数据类型* analyzer : 分词器类型* index : 是否索引(默认:true)* Keyword : 短语,不进行分词*/@Field(type = FieldType.Text, analyzer = "ik_max_word")private String title;//商品名称@Field(type = FieldType.Keyword)private String category;//分类名称@Field(type = FieldType.Double)private Double price;//商品价格@Field(type = FieldType.Keyword, index = false)private String images;//图片地址
}

提供接口：

import com.congge.entity.Product;
import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;
import org.springframework.stereotype.Repository;@Repository
public interface ProductDao extends ElasticsearchRepository{}

配置类：

import lombok.Data;
import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
//import org.springframework.data.elasticsearch.config.AbstractElasticsearchConfiguration;@ConfigurationProperties(prefix = "elasticsearch")
@Configuration
@Data
public class EsConfig extends com.congge.config.AbstractElasticsearchConfiguration {private String host ;private Integer port ;//重写父类方法@Overridepublic RestHighLevelClient elasticsearchClient() {RestClientBuilder builder = RestClient.builder(new HttpHost(host, port));RestHighLevelClient restHighLevelClient = newRestHighLevelClient(builder);return restHighLevelClient;}
}

import org.elasticsearch.client.RestHighLevelClient;
import org.springframework.context.annotation.Bean;
import org.springframework.data.elasticsearch.config.ElasticsearchConfigurationSupport;
import org.springframework.data.elasticsearch.core.ElasticsearchOperations;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;public abstract class AbstractElasticsearchConfiguration extends ElasticsearchConfigurationSupport {//需重写本方法public abstract RestHighLevelClient elasticsearchClient();@Bean(name = { "elasticsearchOperations", "elasticsearchTemplate" })public ElasticsearchOperations elasticsearchOperations(ElasticsearchConverter elasticsearchConverter) {return new ElasticsearchRestTemplate(elasticsearchClient(), elasticsearchConverter);}
}

测试1：

import com.congge.entity.Product;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import org.springframework.test.context.junit4.SpringRunner;@RunWith(SpringRunner.class)
@SpringBootTest
public class EsIndexTest {//注入 ElasticsearchRestTemplate@Autowiredprivate ElasticsearchRestTemplate elasticsearchRestTemplate;//创建索引并增加映射配置@Testpublic void createIndex(){//创建索引，系统初始化会自动创建索引System.out.println("创建索引");}@Testpublic void deleteIndex(){//创建索引，系统初始化会自动创建索引boolean flg = elasticsearchRestTemplate.deleteIndex(Product.class);System.out.println("删除索引 = " + flg);}}

测试2：

import com.congge.dao.ProductDao;
import com.congge.entity.Product;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.index.query.TermQueryBuilder;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Sort;
import org.springframework.test.context.junit4.SpringRunner;import java.util.ArrayList;
import java.util.List;@RunWith(SpringRunner.class)
@SpringBootTest
public class EsDocTest {@Autowiredprivate ProductDao productDao;/*** 新增*/@Testpublic void save() {Product product = new Product();product.setId(2L);product.setTitle("ipad mini");product.setCategory("ipad");product.setPrice(1998.0);product.setImages("http://ipad.jpg");productDao.save(product);}//修改@Testpublic void update(){Product product = new Product();product.setId(2L);product.setTitle("iphone");product.setCategory("mobile");product.setPrice(6999.0);product.setImages("http://www.phone.jpg");productDao.save(product);}//根据 id 查询@Testpublic void findById(){Product product = productDao.findById(2L).get();System.out.println(product);}//查询所有@Testpublic void findAll(){Iterable products = productDao.findAll();for (Product product : products) {System.out.println(product);}}//删除@Testpublic void delete(){Product product = new Product();product.setId(2L);productDao.delete(product);}//批量新增@Testpublic void saveAll(){List productList = new ArrayList<>();for (int i = 0; i < 10; i++) {Product product = new Product();product.setId(Long.valueOf(i));product.setTitle("iphone" + i);product.setCategory("mobile");product.setPrice(5999.0 + i);product.setImages("http://www.phone.jpg");productList.add(product);}productDao.saveAll(productList);}//分页查询@Testpublic void findByPageable(){//设置排序(排序方式，正序还是倒序，排序的 id)Sort sort = Sort.by(Sort.Direction.DESC,"id");int currentPage=0;//当前页，第一页从 0 开始， 1 表示第二页int pageSize = 5;//每页显示多少条//设置查询分页PageRequest pageRequest = PageRequest.of(currentPage, pageSize,sort);//分页查询Page productPage = productDao.findAll(pageRequest);for (Product Product : productPage.getContent()) {System.out.println(Product);}}/*** term 查询* search(termQueryBuilder) 调用搜索方法，参数查询构建器对象*/@Testpublic void termQuery(){TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("title", "iphone");Iterable products = productDao.search(termQueryBuilder);for (Product product : products) {System.out.println(product);}}/*** term 查询加分页*/@Testpublic void termQueryByPage(){int currentPage= 0 ;int pageSize = 5;//设置查询分页PageRequest pageRequest = PageRequest.of(currentPage, pageSize);TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("title", "phone");Iterable products =productDao.search(termQueryBuilder,pageRequest);for (Product product : products) {System.out.println(product);}}}

五、将mysql数据写入Elasticsearch例子

package com.example.esdemo.service.impl;import com.example.esdemo.config.DBHelper;
import com.example.esdemo.imports.ImportDb2Es;
import com.example.esdemo.service.ImportService;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.bulk.BackoffPolicy;
import org.elasticsearch.action.bulk.BulkProcessor;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.unit.ByteSizeUnit;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.TimeValue;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.concurrent.TimeUnit;
import java.util.function.BiConsumer;/*** 导入db2es 实现类*/
@Component
public class ImportServiceImpl implements ImportService {private static final Logger logger = LogManager.getLogger(ImportServiceImpl.class);@Autowiredprivate RestHighLevelClient client;@Overridepublic void importDb2Es(ImportDb2Es importDb2Es) {writeMySQLDataToES(importDb2Es.getDbTableName(),importDb2Es.getDbTableName());}private void writeMySQLDataToES(String tableName,String esIndeName) {BulkProcessor bulkProcessor = getBulkProcessor(client);Connection connection = null;PreparedStatement ps = null;ResultSet rs = null;try {connection = DBHelper.getConn();logger.info("start handle data :" + tableName);String sql = "select * from " + tableName;ps = connection.prepareStatement(sql, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);// 根据自己需要设置 fetchSizeps.setFetchSize(20);rs = ps.executeQuery();ResultSetMetaData colData = rs.getMetaData();ArrayList> dataList = new ArrayList<>();HashMap map = null;int count = 0;// c 就是列的名字   v 就是列对应的值String c = null;String v = null;while (rs.next()) {count++;map = new HashMap(128);for (int i = 1; i < colData.getColumnCount(); i++) {c = colData.getColumnName(i);v = rs.getString(c);map.put(c, v);}dataList.add(map);// 每1万条 写一次   不足的批次的数据 最后一次提交处理if (count % 10000 == 0) {logger.info("mysql handle data  number:" + count);// 将数据添加到 bulkProcessorfor (HashMap hashMap2 : dataList) {bulkProcessor.add(new IndexRequest(esIndeName).source(hashMap2));}// 每提交一次 清空 map 和  dataListmap.clear();dataList.clear();}}// 处理 未提交的数据for (HashMap hashMap2 : dataList) {bulkProcessor.add(new IndexRequest(esIndeName).source(hashMap2));}bulkProcessor.flush();} catch (SQLException e) {e.printStackTrace();} finally {try {rs.close();ps.close();connection.close();boolean terinaFlag = bulkProcessor.awaitClose(150L, TimeUnit.SECONDS);logger.info(terinaFlag);} catch (Exception e) {e.printStackTrace();}}}private BulkProcessor getBulkProcessor(RestHighLevelClient client) {BulkProcessor bulkProcessor = null;try {BulkProcessor.Listener listener = new BulkProcessor.Listener() {@Overridepublic void beforeBulk(long executionId, BulkRequest request) {logger.info("Try to insert data number : "+ request.numberOfActions());}@Overridepublic void afterBulk(long executionId, BulkRequest request,BulkResponse response) {logger.info("************** Success insert data number : "+ request.numberOfActions() + " , id: " + executionId);}@Overridepublic void afterBulk(long executionId, BulkRequest request, Throwable failure) {logger.error("Bulk is unsuccess : " + failure + ", executionId: " + executionId);}};BiConsumer> bulkConsumer = (request, bulkListener) -> client.bulkAsync(request, RequestOptions.DEFAULT, bulkListener);BulkProcessor.Builder builder = BulkProcessor.builder(bulkConsumer, listener);builder.setBulkActions(5000);builder.setBulkSize(new ByteSizeValue(100L, ByteSizeUnit.MB));builder.setConcurrentRequests(10);builder.setFlushInterval(TimeValue.timeValueSeconds(100L));builder.setBackoffPolicy(BackoffPolicy.constantBackoff(TimeValue.timeValueSeconds(1L), 3));// 注意点：让参数设置生效bulkProcessor = builder.build();} catch (Exception e) {e.printStackTrace();try {bulkProcessor.awaitClose(100L, TimeUnit.SECONDS);} catch (Exception e1) {logger.error(e1.getMessage());}}return bulkProcessor;}
}