在java中ElasticSearch如何进行高亮

在 Java 中使用 Elasticsearch 进行高亮可以通过使用 HighlightBuilder 类来实现。下面是一个简单的示例代码：

SearchRequest searchRequest = new SearchRequest("index_name");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
MatchQueryBuilder matchQueryBuilder = new MatchQueryBuilder("field_name", "search_text");
searchSourceBuilder.query(matchQueryBuilder);

HighlightBuilder highlightBuilder = new HighlightBuilder();
highlightBuilder.field("field_name");
highlightBuilder.requireFieldMatch(false);
highlightBuilder.preTags("<em>");
highlightBuilder.postTags("</em>");
searchSourceBuilder.highlighter(highlightBuilder);

searchRequest.source(searchSourceBuilder);

SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

SearchHits hits = searchResponse.getHits();
for (SearchHit hit : hits) {
    Map<String, HighlightField> highlightFields = hit.getHighlightFields();
    HighlightField highlight = highlightFields.get("field_name");
    Text[] fragments = highlight.fragments();
    String fragmentString = fragments[0].string();
    System.out.println(fragmentString);
}

在上面的代码中，`SearchRequest` 和 `SearchSourceBuilder` 用于构建搜索请求，`MatchQueryBuilder` 用于设置要搜索的字段及搜索文本。`HighlightBuilder` 用于设置高亮的字段，以及前置和后置标记。最后，调用 `client.search()` 方法执行搜索请求，返回 `SearchResponse` 对象，从中可以获取高亮结果。