ElasticSearch查询高亮显示

1. 需求背景

在使用ES进行搜索时，总需要在查询出来的内容中，把我们的搜索关键字高亮显示出来

2. 实现思路

3. 代码实现

  • 引入maven依赖

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

  • 自定义SearchResultMapper

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    package com.xxx.web.cloud.bot.es.config;

    import com.alibaba.fastjson.JSON;
    import org.elasticsearch.action.search.SearchResponse;
    import org.elasticsearch.search.SearchHit;
    import org.elasticsearch.search.SearchHits;
    import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;
    import org.springframework.data.domain.Pageable;
    import org.springframework.data.elasticsearch.core.SearchResultMapper;
    import org.springframework.data.elasticsearch.core.aggregation.AggregatedPage;
    import org.springframework.data.elasticsearch.core.aggregation.impl.AggregatedPageImpl;

    import java.lang.reflect.Field;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;

    /**
     * @author iseven.yang
     * @date 2023/7/11 19:55
     */
    public class HighlightResultMapper implements SearchResultMapper {
        @Override
        public <T> AggregatedPage<T> mapResults(SearchResponse response, Class<T> clazz, Pageable pageable) {
            long totalHits = response.getHits().getTotalHits();
            List<T> list = new ArrayList<>();
            SearchHits hits = response.getHits();
            if (hits.getHits().length> 0) {
                for (SearchHit searchHit : hits) {
                    Map<String, HighlightField> highlightFields = searchHit.getHighlightFields();
                    T item = JSON.parseObject(searchHit.getSourceAsString(), clazz);
                    Field[] fields = clazz.getDeclaredFields();
                    for (Field field : fields) {
                        field.setAccessible(true);
                        if (highlightFields.containsKey(field.getName())) {
                            try {
                                field.set(item, highlightFields.get(field.getName()).fragments()[0].toString());
                            } catch (IllegalAccessException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                    list.add(item);
                }
            }
            return new AggregatedPageImpl<>(list, pageable, totalHits);
        }

        @Override
        public <T> T mapSearchHit(SearchHit searchHit, Class<T> type) {
            return null;
        }
    }

  • 检索高亮查询

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    public List<AnswerButtonVO> searchQuestion(String searchKey) {
        BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
        // 匹配问题的关键字、
        MatchQueryBuilder matchQueryBuilder = QueryBuilders.matchQuery(QuestionDOC.QUESTION, searchKey);
        boolQueryBuilder.must(matchQueryBuilder);
      
        // 分页数据
        PageRequest pageRequest = PageRequest.of(0, 5);
      
        // 高亮
        HighlightBuilder highlightBuilder = new HighlightBuilder()
                .field(QuestionDOC.QUESTION)
                .preTags(CustomConstant.HIGHLIGHT_PREFIX) //String HIGHLIGHT_PREFIX = "<span class=\"highlight\">";
                .postTags(CustomConstant.HIGHLIGHT_SUFFIX); //String HIGHLIGHT_SUFFIX = "</span>";
      
        NativeSearchQuery nativeSearchQuery = new NativeSearchQueryBuilder()
                .withQuery(boolQueryBuilder)
                .withPageable(pageRequest)
                .withHighlightBuilder(highlightBuilder)
                .build();
      
        AggregatedPage<QuestionDOC> searchPage = elasticsearchRestTemplate.queryForPage(nativeSearchQuery, QuestionDOC.class, new HighlightResultMapper());
        List<QuestionDOC> content = searchPage.getContent();
        ...
    }