solr4分组查询、统计

ModifiableSolrParams params = new ModifiableSolrParams();
params.set("fq", fq);
params.set("facet", "on");
params.set("facet.field", "size","category", "brand");//后面这几个是你分组的属性
params.set("facet.mincount", "1");
params.set("facet.limit", "15");
params.set("q","拉箱");
QueryResponse qresponse = queryserver.query(params);
FacetField facetField = qresponse.getFacetField(Facet_CATEGORY);
List<Count> counts = null;
if (facetField != null) {
 counts = facetField.getValues();
 if (counts != null) {
 for (Count count : counts) {
 System.out.println(count.getName()+" "+count.getCount());
 }
 }
}