mongodb mongotemplate聚合

1.group by并且计算总数

　　@Test
public void insertTest() {
//测试数据
//insertTestData();
Aggregation agg = Aggregation.newAggregation(
//Aggregation.match(Criteria.where("groupId").is(5)),
Aggregation.group("groupId").count().as("total"),
Aggregation.project("total").and("groupId").previousOperation(),
Aggregation.sort(Sort.DEFAULT_DIRECTION, "total"));
List<StaCount> list = mongoTemplate.aggregate(agg, "currentUser", StaCount.class).getMappedResults();
for(StaCount count : list) {
System.out.println(count.getGroupId() + ":" + count.getTotal());
}
　　｝
如果要带其他字段，将红字变为 Aggregation.group("groupId","groupName"...),并将project的and部分去掉即可;

2.Crieria的使用，注意andOperator和orOperator的用法

Aggregation agg = Aggregation.newAggregation( 　　Aggregation.match(new Criteria().andOperator(Criteria.where("onlineTime").gt(new Date())) 　　.orOperator( 　　Criteria.where("offlineTime").gt(new Date()) 　　,Criteria.where("offlineTime").exists(false) ))