在Java中查询es时，怎么指定字符集为utf-8

在Java中查询es时，可以通过设置请求头的方式指定字符集为utf-8，具体代码如下：

SearchRequest searchRequest = new SearchRequest(index);
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchQuery("field", "value"));
searchRequest.source(searchSourceBuilder);
searchRequest.setOptions( RequestOptions.DEFAULT.toBuilder().addHeader("Content-Type", "application/json; charset=utf-8").build());

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

其中，通过设置请求头的方式，将字符集指定为utf-8，即：

.addHeader("Content-Type", "application/json; charset=utf-8")