解决ES searchHit.getHighlightFields()输出null数据到前端

分页，遍历搜索的结果for (SearchHit hit : search.getHits())

接着获取hit.getHighlightFields()，经过调试排查发现获取为null

此时的hit是一个SearchHit对象

我们进入SearchHit类中查看hit.getHighlightFields()方法的源码，发现由于this.highlightFields = null，此方法会返回null

return this.highlightFields == null ? Collections.emptyMap() : this.highlightFields;

因此这里的Map<>自然也就什么都接不到了，highlightFields也为null了。

SearchHit类的hit对象是由search.getHits()得到的，而search是一个SearchResponse类

我们进入getHits方法

public SearchHits getHits() {
    return this.internalResponse.hits();
}

发现其getHits()是另一个类中的hit()

加高亮操作参考：ElasticSearch7.9.3集成Springboot 高亮查询

SpringBoot+Elasticsearch-7.X实现高亮分词搜索

ElasticSearch7.x版本踩坑记录：SpringBoot2.3.x整合ElasticSearch7.x（ElasticsearchRestTemplate）

最后不加高亮操作，直接转为json，然后转为对象，前端也正常了

public List> serchPageBuilder(String keyword, int pageNo, int pageSize) throws IOException {
    if(pageNo <=1) {
        pageNo = 1;
    }
    //条件搜索
    //1、构建搜索请求
    SearchRequest jd_goods = new SearchRequest("jd_goods");
    //2、设置搜索条件，使用该构建器进行查询
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    // 构建精确匹配查询条件
//        TermQueryBuilder termQuery = QueryBuilders.termQuery("title", keyword);
//        TermQueryBuilder termQuery = QueryBuilders.termQuery("title.keyword", keyword);
//        searchSourceBuilder.query(termQuery);




    // 自试 索引查询
//        QueryBuilder queryBuilder = QueryBuilders.matchAllQuery();
    QueryBuilder queryBuilder = QueryBuilders.matchQuery("title", keyword);   // 成功【单子多字都成功】
    searchSourceBuilder.query(queryBuilder);
//        QueryBuilder queryBuilder = QueryBuilders.matchQuery("title", "轻松");   // 成功【单子多字都成功】
//        searchSourceBuilder.query(queryBuilder);



    searchSourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS));
    searchSourceBuilder.from(pageNo);
    searchSourceBuilder.size(pageSize);


//        HighlightBuilder.Field field = new HighlightBuilder.Field("title");
//        field.preTags("");
//        field.postTags("");
//        field.fragmentSize(100);






    HighlightBuilder highlightBuilder = new HighlightBuilder();
    highlightBuilder.requireFieldMatch(true);
    highlightBuilder.field("title");
    highlightBuilder.preTags("");
    highlightBuilder.postTags("");
    // highlightBuilder.requireFieldMatch(false);//匹配第一个即可
    // highlightBuilder.numOfFragments(0);

    searchSourceBuilder.highlighter(highlightBuilder);
    //3、将搜索条件放入搜索请求中
    jd_goods.source(searchSourceBuilder);
    //4、客户端执行搜索请求
    SearchResponse search = restHighLevelClient.search(jd_goods, RequestOptions.DEFAULT);
    System.out.println("共查询到"+search.getHits().getHits().length+"条数据");

    //5、打印测试
    Map map = new HashMap<>();
    ArrayList> list = new ArrayList();
    for (SearchHit hit : search.getHits()) {

        //

        String value = hit.getSourceAsString();
        Content esProductTO = JSON.parseObject(value, Content.class);

        map.put("fragment", JSON.toJSONString(esProductTO.getTitle()));
        System.out.println(esProductTO.getTitle());


        map.put("fr", JSON.toJSONString(esProductTO.getTitle()));


        map = hit.getSourceAsMap();
        //System.out.println("hit = " + hit);
        list.add(map);

//            System.out.println("hit：n" + hit);
//            System.out.println(hit.getHighlightFields() == null);
//            System.out.println(hit.getHighlightFields().get("title"));
//            Map highlightFields = hit.getHighlightFields();
//            System.out.println("highlightFields = " + highlightFields);
//            HighlightField title_high = highlightFields.get("title");
//            String fr = "";
//            for (Text fragment : title_high.fragments()) {
//                System.out.println("fragment = " + fragment);
//                fr = fragment.toString();
//                map.put("fragment", JSON.toJSONString(fragment.toString()));
//
//            }
//            System.out.println("fr = " + fr);
//            // map.put("fragment", JSON.toJSONString(fragment));
//            map.put("fr", JSON.toJSONString(fr));
//            //System.out.println("title_high_______fragments = " + title_high.fragments().toString());
//            map = hit.getSourceAsMap();
//            //System.out.println("hit = " + hit);
//            list.add(map);
    }
    return list;
}