mongoDB Java连接实现:
1.Mongo类(mongodb-java-driver original)
@Deprecated
Mongo mongo = new Mongo("IP", 27017);
2.MongoClient类（mongodb-java-driver since 2.10.0）
MongoClient mongoClient = new MongoClient("IP", 27017);
3.MongoTemplate类（Spring Data的 MongoDB项目）
MongoTemplate mongoTemplate = new MongoTemplate(new SimpleMongoDbFactory(new MongoClient("IP", 27017), "testdb"));
4.Hibernate OGM（Hibernate的一个项目）
For JPA: use EntityManager
Without JPA: use OgmSession
5.Morphia (Apache许可/Google Code项目，提供一系列围绕 Mongo Java驱动程序的注解和包装程序)
@Entity + @Id
@Embedded, @Reference, (@Property), ...
Morphia morphia = new Morphia();
morphia.mapPackage("mongodbDemo");
final Datastore datastore = morphia.createDatastore(new MongoClient("localhost"), "morphia_example");
datastore.save(entity);
备注：
Spring Data MongoDB 对比 Hibernate OGM
https://stackoverflow.com/questions/23163853/whats-the-difference-between-spring-data-mongodb-and-hibernate-ogm-for-mongodb
Spring Data MongoDB 对比 morphia
https://stackoverflow.com/questions/37584915/morphia-vs-spring-data-mongo
Spring Data MongoDB 对比 morphia、mongo4j
https://stackoverflow.com/questions/5837135/how-do-morphia-mongo4j-and-spring-data-for-mongodb-compare
Spring Data MongoDB 对比 MongoDB Java Driver, Jongo, Morphia