java中操作MongoDB

1：没有实体，没有使用MongoDB

            1：根据id查询

      BasicDBObject queryObject = new BasicDBObject("_id",new ObjectId(""));
        collection.find(queryObject);

            2：指定返回的数据

public static Object findById(MongoCollection collection, String id) {

        BasicDBObject queryObject = new BasicDBObject("_id",new ObjectId(""));
        collection.find(queryObject);


        //指定要查询的字段
        BasicDBObject field = new BasicDBObject();
//        field.put("intro", 1);

        FindIterable findIterable = collection.find(queryObject).projection(field);

        MongoCursor cursor = findIterable.iterator();
        if (cursor.hasNext()){
            return cursor.next();
        }else {
            return null;
        }
    }