文章目录

• • • 1. 数据准备
    • 2. ElasticSearch 搜索结果返回指定的字段
    • 3. SpringBoot整合ES 搜索结果返回指定的字段
    • 4. 源码接口

from：指定搜索结果的起始位置，默认为0。
size：指定返回的文档数量，默认为10。
sort：指定搜索结果的排序方式，可以按照字段升序或降序排列。
query：指定搜索的查询条件，可以使用各种查询语句进行搜索。
filter：指定搜索的过滤条件，可以使用各种过滤语句进行过滤。
highlight：指定搜索结果中需要高亮显示的字段。
aggregations：指定搜索结果的聚合方式，可以对搜索结果进行分组统计。
suggest：指定搜索建议，可以根据用户输入的关键词提供搜索建议。

1. 数据准备

PUT /my_index/_doc/1
{"title": "文雅酒店","content": "青岛","price": 556
}PUT /my_index/_doc/2
{"title": "金都嘉怡假日酒店","content": "北京","price": 337
}PUT /my_index/_doc/3
{"title": "金都欣欣酒店","content": "天津","price": 200
}PUT /my_index/_doc/4
{"title": "金都酒店","content": "北京","price": 500
}

2. ElasticSearch 搜索结果返回指定的字段

在 ElasticSearch 中，可以使用 _source 字段来指定返回的字段。默认情况下，ElasticSearch 返回匹配文档的所有字段，但是可以通过 _source 字段来指定只返回需要的字段，这样可以减少网络传输和解析的开销，提高搜索性能。

以下是一个示例，假设我们有一个名为 my_index 的索引，其中包含 title 、content和price 这3个字段，我们只需要返回 title 字段：

GET /my_index/_search
{"_source": ["title"],"query": {"match": {"content": "北京"}}
}

在上面的示例中，我们使用 _source 字段来指定只返回 title 字段，同时使用 match 查询来搜索包含 北京 的文档。

{"took" : 2,"timed_out" : false,"_shards" : {"total" : 1,"successful" : 1,"skipped" : 0,"failed" : 0},"hits" : {"total" : {"value" : 2,"relation" : "eq"},"max_score" : 1.3862944,"hits" : [{"_index" : "my_index","_type" : "_doc","_id" : "2","_score" : 1.3862944,"_source" : {"title" : "金都嘉怡假日酒店"}},{"_index" : "my_index","_type" : "_doc","_id" : "4","_score" : 1.3862944,"_source" : {"title" : "金都酒店"}}]}
}

如果需要返回多个字段，可以将字段名添加到 _source 字段的数组中，如下所示：

GET /my_index/_search
{"_source": ["title", "content"],"query": {"match": {"content": "北京"}}
}

在上面的示例中，我们指定返回 title 和 content 两个字段。

需要注意的是，如果某个字段被存储在索引中，但是没有被指定在 _source 字段中，那么在搜索结果中将无法获取该字段的值。因此，在创建索引时，需要根据实际需求来决定哪些字段需要被存储在索引中。

3. SpringBoot整合ES 搜索结果返回指定的字段

@Slf4j
@Service
public class ElasticSearchImpl {@Autowiredprivate RestHighLevelClient restHighLevelClient;public void searchUser() throws IOException {SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();// query 参数MatchQueryBuilder matchQueryBuilder = new MatchQueryBuilder("content","北京");searchSourceBuilder.query(matchQueryBuilder);// _source 参数searchSourceBuilder.fetchSource(new String[]{"title","content"},null);SearchRequest searchRequest = new SearchRequest(new String[]{"my_index"},searchSourceBuilder);SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);// 搜索结果SearchHits searchHits = searchResponse.getHits();SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {// hits.hits._source：匹配的文档的原始数据String sourceAsString = hit.getSourceAsString();System.out.println("sourceAsString = " + sourceAsString);}System.out.println(searchResponse);}
}

{"took": 1,"timed_out": false,"_shards": {"total": 1,"successful": 1,"skipped": 0,"failed": 0},"hits": {"total": {"value": 2,"relation": "eq"},"max_score": 1.3862944,"hits": [{"_index": "my_index","_type": "_doc","_id": "2","_score": 1.3862944,"_source": {"title": "金都嘉怡假日酒店","content": "北京"}},{"_index": "my_index","_type": "_doc","_id": "4","_score": 1.3862944,"_source": {"title": "金都酒店","content": "北京"}}]}
}

4. 源码接口

public final class SearchSourceBuilder implements Writeable, ToXContentObject, Rewriteable {/*** Indicates whether the response should contain the stored _source for every hit*/public SearchSourceBuilder fetchSource(boolean fetch) {FetchSourceContext fetchSourceContext = this.fetchSourceContext != null ? this.fetchSourceContext: FetchSourceContext.FETCH_SOURCE;this.fetchSourceContext = new FetchSourceContext(fetch, fetchSourceContext.includes(), fetchSourceContext.excludes());return this;}/*** Indicate that _source should be returned with every hit, with an* "include" and/or "exclude" set which can include simple wildcard* elements.** @param include*            An optional include (optionally wildcarded) pattern to filter*            the returned _source* @param exclude*            An optional exclude (optionally wildcarded) pattern to filter*            the returned _source*/public SearchSourceBuilder fetchSource(@Nullable String include, @Nullable String exclude) {return fetchSource(include == null ? Strings.EMPTY_ARRAY : new String[] { include }, exclude == null ? Strings.EMPTY_ARRAY: new String[] { exclude });}/*** Indicate that _source should be returned with every hit, with an* "include" and/or "exclude" set which can include simple wildcard* elements.** @param includes*            An optional list of include (optionally wildcarded) pattern to*            filter the returned _source* @param excludes*            An optional list of exclude (optionally wildcarded) pattern to*            filter the returned _source*/public SearchSourceBuilder fetchSource(@Nullable String[] includes, @Nullable String[] excludes) {FetchSourceContext fetchSourceContext = this.fetchSourceContext != null ? this.fetchSourceContext: FetchSourceContext.FETCH_SOURCE;this.fetchSourceContext = new FetchSourceContext(fetchSourceContext.fetchSource(), includes, excludes);return this;}/*** Indicate how the _source should be fetched.*/public SearchSourceBuilder fetchSource(@Nullable FetchSourceContext fetchSourceContext) {this.fetchSourceContext = fetchSourceContext;return this;}
}