Java POJO与MongoDB不提取数据

Question

我是第一次使用Java。数据库是MongoDB。我正在尝试从MongoDB中提取数据。跟随link

下面是数据库查询的代码

MongoCollection<Person> collection = database.getCollection("people", Person.class);

BasicDBObject whereQuery = new BasicDBObject();

List<BasicDBObject> obj = new ArrayList<BasicDBObject>();

obj.add(new BasicDBObject("name","someName"));
obj.add(new BasicDBObject("age","someAge"));
whereQuery.put("$and", obj);

FindIterable<Person> iterDoc = collection.find(whereQuery);
MongoCursor<Person> it = iterDoc.iterator();

while (it.hasNext()) {  

  Person data = it.next();
  System.out.println(data);

}

我正在通过链接使用相同的POJO

运行代码时，我得到以下输出

com.test.pojo.document.Person@6572421

此输出表示什么以及为什么不显示结果。如果我跳过POJO并按如下所示使用它，则可以正常显示数据库结果

MongoClient mongo = MongoClients.create("mongodb://localhost:27017");

MongoDatabase database = mongo.getDatabase("DBname");  

MongoCollection<Person> collection = database.getCollection("people");

BasicDBObject whereQuery = new BasicDBObject();

List<BasicDBObject> obj = new ArrayList<BasicDBObject>();

obj.add(new BasicDBObject("name","someName"));
obj.add(new BasicDBObject("age","someAge"));
whereQuery.put("$and", obj);

FindIterable<Person> iterDoc = collection.find(whereQuery);
MongoCursor<Person> it = iterDoc.iterator();

while (it.hasNext()) {  

  Person data = it.next();
  System.out.println(data);

}