usering mongotemplate bases on spring-Data-mongo

 1、find

• mongoTemplate.find(Query query, Class<T> entityClass ) 
  • return value : List<T>
  •  example:    List<users> users = mongoTemplate.find(new Query(Criteria.where("age").is(20).and("name").is("zhangsan")), users.class);
  •                     List<users> users = mongoTemplate.find(new Query(Criteria.where("age").is(20).and("name").is("northeasttycoon")), BasicDBObject.class);
• mongoTemplate.find(Query query, Class<T> entityClass,String Collectionname )
  • result:  List<T>
  • example:  List<users> users1 = mongoTemplate.find(new Query(Criteria.where("age").is(20).and("name").is("northeasttycoon")), users.class, "uses");
• mongoTemplate.findAll(Class<T> entityClass)
  • result: List<T>
  • example: List<users> userList= mongoTemplate.findAll(users.class);
• code example:

                // query all data

                List<users> usersList = mongoTemplate.findAll(users.class);

               // query users collection base on condition

               List<users> users = mongoTemplate.find(new Query(Criteria.where("age").is(20).and("name").is("zhangsan")), users.class);

2、Aggregation

• Aggregation.project(String... fields)
  • result: ProjectionOperation
  • example : ProjectionOperation project = Aggregation.project("age", "name");
• Aggregation.match（Criteria criteria）
  • result:：MatchOperation
  • example: MatchOperation match = Aggregation.match( Criteria().where("age").is(20));
• Aggregation.group（String... fields ）
  • result: GroupOperation
  • example: GroupOperation group = Aggregation.group("username","age").sum("age").as("count");