multi search API 允许在同一API中执行多个搜索请求。它的端点（endpoint）是 _msearch 。
首先请看MultiSearch API Query 文档
SearchRequestBuilder srb1 = client
.prepareSearch().setQuery(QueryBuilders.queryStringQuery("elasticsearch")).setSize(1);
SearchRequestBuilder srb2 = client
.prepareSearch().setQuery(QueryBuilders.matchQuery("name", "kimchy")).setSize(1);
MultiSearchResponse sr = client.prepareMultiSearch()
.add(srb1)
.add(srb2)
.get();
// You will get all individual responses from MultiSearchResponse#getResponses()
long nbHits = 0;
for (MultiSearchResponse.Item item : sr.getResponses()) {
SearchResponse response = item.getResponse();
nbHits += response.getHits().getTotalHits();
}