[Spring Boot]12 ElasticSearch实现分词搜索功能

一、前言

我们在使用搜索功能的时候，有时，为了使搜索的结果更多更广，比如搜索字符串“领导力”，希望有这些组合的结果（领导力、领导、领、导、力）都要能够全部展示出来。
这里我们引入ElasticSearch结合分词插件，来实现这样的搜索功能。

二、搜索功能的需求

比如：一款app需要对“课程”进行关键字搜索。
首先：课程包含的信息有：标题、子标题、讲师、简介、所属标签、封面图片、讲数等等。
搜索的需求为：输入关键字，要能分词匹配课程的这些信息：标题、子标题、讲师、所属标签。
搜索需求：搜索结果的原型图如下图所示：

红色高亮为搜索结果，覆盖了标题、子标题、所属标签、讲师名称，并能进行分词搜索且关键字高亮。

三、需求开发

1、服务器安装ElasticSearch和IK分词器

参考链接: [Linux安装软件详解系列]05 安装ElasticSearch和IK分词器

2、需求开发

1）pom.xml引入jar包：

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

2）yml增加配置

  // 安装ElasticSearch时对应的信息
  elasticsearch:
    rest:
      uris: http://ip:9200
      username: test
      password: 123456

3）配置类ElasticsearchConfig

ElasticsearchConfig：

package com.test.api.config;
import org.elasticsearch.client.RestHighLevelClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.elasticsearch.client.ClientConfiguration;
import org.springframework.data.elasticsearch.client.RestClients;
import org.springframework.data.elasticsearch.repository.config.EnableElasticsearchRepositories;
/**
 * es 配置
 *
 * @author /
 */
@EnableElasticsearchRepositories(basePackages = {
    
    "com.test.bi.*.repository"})
@Configuration
public class ElasticsearchConfig {
    
    
    @Value("${spring.elasticsearch.rest.uris}")
    private String hostAndPort;
    @Value("${spring.elasticsearch.rest.username}")
    private String username;
    @Value("${spring.elasticsearch.rest.password}")
    private String password;
    @Bean
    public RestHighLevelClient elasticsearchClient() {
    
    
        ClientConfiguration clientConfiguration = ClientConfiguration.builder()
                .connectedTo(hostAndPort)
                .withBasicAuth(username, password)
                .build();
        return RestClients.create(clientConfiguration).rest();
    }
}

4）工具类ElasticsearchUtil

ElasticsearchUtil：

package com.test.common.util;
import cn.hutool.core.collection.CollectionUtil;
import cn.hutool.json.JSONUtil;
import com.github.pagehelper.PageInfo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.search.SearchScrollRequest;
import org.elasticsearch.action.support.WriteRequest;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.text.Text;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ReflectionUtils;
import javax.annotation.Resource;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
/**
 * es 工具类
 *
 * @author /
 */
@Slf4j
@Component
public class ElasticsearchUtil {
    
    
    @Resource
    private RestHighLevelClient restHighLevelClient;
    /**
     * 普通查询
     *
     * @param index               索引名称
     * @param searchSourceBuilder 查询条件构建
     * @param resultClass         类
     * @param currentPage         当前页 分页的页码，不是es 的
     * @param size                每页显示数据
     */
    public <T> PageInfo<T> page(String index, SearchSourceBuilder searchSourceBuilder, Class<T> resultClass,
                                int currentPage, int size, List<String> highFields) {
    
    
        SearchRequest request = new SearchRequest(index);
        // 高亮字段设置
        if (CollectionUtil.isNotEmpty(highFields)) {
    
    
            buildHighLight(searchSourceBuilder, highFields);
        }
        // 分页
        int num = (currentPage - 1) * size;
        searchSourceBuilder.from(num)
                .size(size);
        request.source(searchSourceBuilder);
        SearchResponse response = null;
        try {
    
    
            response = restHighLevelClient.search(request, RequestOptions.DEFAULT);
        } catch (IOException e) {
    
    
            e.printStackTrace();
        }
        assert response != null;
        return analysisResponse(response, resultClass, currentPage, size, highFields);
    }

    /**
     * 解析es 查询结果
     *
     * @param response    返回
     * @param resultClass 转换成对象类
     */
    private <T> PageInfo<T> analysisResponse(SearchResponse response, Class<T> resultClass, int currentPage, int size, List<String> highFields) {
    
    
        SearchHit[] searchHits = response.getHits().getHits();
        List<T> retList = new ArrayList<>(searchHits.length);
        for (SearchHit searchHit : searchHits) {
    
    
            String strJson = searchHit.getSourceAsString();
            T t = JSONUtil.toBean(strJson, resultClass);
            try {
    
    
                setId(resultClass, t, String.valueOf(searchHit.getId()));
            } catch (Exception e) {
    
    
                log.info("es 查询数据设置主键id值异常", e);
            }
            // 高亮字段设置后，组织结果，es 结果建议与java 对象 名称一直，基本要求
            if (!CollectionUtils.isEmpty(highFields)) {
    
    
                Map<String, HighlightField> highlightFieldMap = searchHit.getHighlightFields();
                HighlightField highlightField;
                for (String field : highFields) {
    
    
                    highlightField = highlightFieldMap.get(field);
                    if (highlightField != null) {
    
    
                        // 获取指定字段的高亮片段
                        Text[] fragments = highlightField.getFragments();
                        // 将这些高亮片段拼接成一个完整的高亮字段
                        StringBuilder builder = new StringBuilder();
                        for (Text text : fragments) {
    
    
                            builder.append(text);
                        }
                        // 设置到实体类中
                        setValue(resultClass, t, builder.toString(), field);
                    }
                }
            }
            retList.add(t);
        }
        long totalNum = response.getHits().getTotalHits();
        PageInfo<T> pageVo = new PageInfo<>();
        pageVo.setPageNum(currentPage);
        pageVo.setPageSize(size);
        pageVo.setTotal(totalNum);
        pageVo.setList(retList);
        return pageVo;
    }

    /**
     * 对象id 为空时，给id 赋值
     *
     * @param resultClass 类
     * @param t           对象
     * @param id          主键id 的值
     */
    @SneakyThrows
    private <T> void setId(Class<T> resultClass, T t, Object id) {
    
    
        Field field = ReflectionUtils.findField(resultClass, "id");
        if (null != field) {
    
    
            field.setAccessible(true);
            Object object = ReflectionUtils.getField(field, t);
            if (object == null) {
    
    
                Method method = resultClass.getMethod("setId", String.class);
                ReflectionUtils.invokeMethod(method, t, id);
            }
        }
    }

    /**
     * 指定字段赋值
     *
     * @param resultClass 类
     * @param t           对象
     * @param fieldValue  字段名
     * @param fieldName   字段值
     */
    @SneakyThrows
    private <T> void setValue(Class<T> resultClass, T t, Object fieldValue, String fieldName) {
    
    
        Field field = ReflectionUtils.findField(resultClass, fieldName);
        if (null != field) {
    
    
            field.setAccessible(true);
            String methodName = "set".concat(captureName(fieldName));
            Method method = resultClass.getMethod(methodName, String.class);
            ReflectionUtils.invokeMethod(method, t, fieldValue);
        }
    }

    /**
     * 进行字母的ascii编码前移，效率要高于截取字符串进行转换的操作
     *
     * @param str /
     */
    private String captureName(String str) {
    
    
        char[] cs = str.toCharArray();
        cs[0] -= 32;
        return String.valueOf(cs);
    }

    /**
     * 设置高亮
     *
     * @param searchSourceBuilder /
     * @param fields              高亮字段
     */
    private void buildHighLight(SearchSourceBuilder searchSourceBuilder, List<String> fields) {
    
    
        // 设置高亮
        HighlightBuilder highlightBuilder = new HighlightBuilder();
        fields.forEach(highlightBuilder::field);
        highlightBuilder.preTags("<em>");
        highlightBuilder.postTags("</em>");
        // 给请求设置高亮
        searchSourceBuilder.highlighter(highlightBuilder);
    }

    /**
     * es Scroll 深分页 定义bean
     */
    @AllArgsConstructor
    @Data
    public class ScrollPageBean<T> {
    
    
        private String scrollId;
        private PageInfo<T> scrollPage;
    }
}

5）返回的数据BO封装

package com.test.bi.bo.course;

import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
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;

import java.io.Serializable;

/**
 * 课程-搜索
 *
 * @author /
 */
@Document(indexName = "course_es", type = "_doc", replicas = 0)
@Data
public class CourseEsDTO implements Serializable {
    
    

    @ApiModelProperty(value = "课程编号")
    @Id
    private String id;

    @ApiModelProperty(value = "标题")
    @Field(type = FieldType.Text, analyzer = "ik_max_word")
    private String name;

    @ApiModelProperty(value = "讲师名称")
    @Field(type = FieldType.Text, analyzer = "ik_max_word")
    private String teacherName;

    @ApiModelProperty(value = "子标题")
    @Field(type = FieldType.Text, analyzer = "ik_max_word")
    private String subtitle;

    @ApiModelProperty(value = "所属标签名称列表")
    @Field(type = FieldType.Text, analyzer = "ik_max_word")
    private String labelName;

    @ApiModelProperty(value = "封面图片")
    @Field(type = FieldType.Text)
    private String pic;

    @ApiModelProperty(value = "讲数")
    @Field(type = FieldType.Integer)
    private Integer count;
}

6）保存数据至ElasticSearch

保存数据到ElasticSearch中，通常有两种方式：一种是通过ElasticsearchRepository 接口，另一种是通过ElasticsearchTemplate接口，我们使用ElasticsearchRepository接口来实现。
实现接口：CourseEsRepository，可以放在mapper里面。

package com.test.bi.mapper;

import com.test.bi.bo.course.CourseEsDTO;
import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;
import org.springframework.stereotype.Repository;

/**
 * 课程-搜索
 *
 * @author /
 */
@Repository
public interface CourseEsRepository extends ElasticsearchRepository<CourseEsDTO, String> {
    
    
}

保存数据：

@Resource
private CourseEsRepository courseEsRepository;

@Override
public void saveCourseEs() {
    
    
    try {
    
    
        courseEsRepository.deleteAll();
        // 从库中取数据
        List<CourseEsDTO> list = courseMapper.getCourseEsList();
        if (IterUtil.isNotEmpty(list)) {
    
    
            courseEsRepository.saveAll(list);
        }
    } catch (Exception e) {
    
    
        log.error("es error:{}", e.getMessage());
    }
}

7）根据关键字搜索，分页返回数据

@Override
public PageInfo<CourseEsDTO> getCourseEs(String keywords, Integer pageNum, Integer pageSize) {
    
    
    // 使用best_fields模式, 对多个字段进行查询
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    String[] queryFields = {
    
    "teacherName", "subtitle", "labelName"
    };
    QueryBuilder queryBuilder = QueryBuilders.multiMatchQuery(keywords, queryFields)
            .field("name", 2F)
            .tieBreaker(0.3F);
    searchSourceBuilder.query(queryBuilder);
    // 高亮
    List<String> highFields = ListUtil.toList(queryFields);
    highFields.add("name");
    // 分页返回数据
    return elasticsearchUtil.page("course_es", searchSourceBuilder, CourseEsDTO.class, pageNum,
            pageSize, highFields);
}

8）总结

总结一下，就是通过一个小的需求例子，很好地实现了分词搜索，并且要能够高亮显示关键字。
具体的ElasticSearch和对应iK分词的代码功能，我就不一一展开了，可以去官方查看，这里只是演示一下实现搜索功能的简单过程，希望对大家有所帮助。