What Java ORM do you prefer and why

Question

It s a pretty open ended question   I ll be starting out a new project and am looking at different ORMs to integrate with database access   Do you have any favorites  Are there any you would advise staying clear of

User · Answer

None  because having an ORM takes too much control away with small benefits  The time savings gained are easily blown away when you have to debug abnormalities resulting from the use of the ORM  Furthermore  ORMs discourage developers from learning SQL and how relational databases work and using this for their benefit

User · Answer

Hibernate  because it s basically the defacto standard in Java and was one of the driving forces in the creation of the JPA  It s got excellent support in Spring  and almost every Java framework supports it  Finally  GORM is a really cool wrapper around it doing dynamic finders and so on using Groovy   It s even been ported to  NET  NHibernate  so you can use it there too

User · Answer

Many ORM s are great  you need to know why you want to add abstraction on top of JDBC  I can recommend http   www jooq org to you  disclaimer  I m the creator of jOOQ  so this answer is biased   jOOQ embraces the following paradigm    SQL is a good thing  Many things can be expressed quite nicely in SQL  There is no need for complete abstraction of SQL  The relational data model is a good thing  It has proven the best data model for the last 40 years  There is no need for XML databases or truly object oriented data models  Instead  your company runs several instances of Oracle  MySQL  MSSQL  DB2 or any other RDBMS  SQL has a structure and syntax  It should not be expressed using  low-level  String concatenation in JDBC - or  high-level  String concatenation in HQL - both of which are prone to hold syntax errors  Variable binding tends to be very complex when dealing with major queries  THAT is something that should be abstracted  POJO s are great when writing Java code manipulating database data  POJO s are a pain to write and maintain manually  Code generation is the way to go  You will have compile-safe queries including datatype-safety  The database comes first  While the application on top of your database may change over time  the database itself is probably going to last longer  Yes  you do have stored procedures and user defined types  UDT s  in your legacy database  Your database-tool should support that    There are many other good ORM s  Especially Hibernate or iBATIS have a great community  But if you re looking for an intuitive  simple one  I ll say give jOOQ a try  You ll love it   -   Check out this example SQL        Select authors with books that are sold out   SELECT        FROM T AUTHOR a    WHERE EXISTS  SELECT 1                    FROM T BOOK                   WHERE T BOOK STATUS    SOLD OUT                      AND T BOOK AUTHOR ID   a ID     And how it can be expressed in jOOQ        Alias the author table   TAuthor a   T AUTHOR as  a          Use the aliased table in the select statement   create selectFrom a           whereExists create selectOne                               from T BOOK                              where T BOOK STATUS equal TBookStatus SOLD OUT                              and T BOOK AUTHOR ID equal a ID

User · Answer

SimpleORM  because it is straight-forward and no-magic  It defines all meta data structures in Java code and is very flexible      SimpleORM provides similar   functionality to Hibernate by mapping   data in a relational database to Java   objects in memory   Queries can be   specified in terms of Java objects    object identity is aligned with   database keys  relationships between   objects are maintained and modified   objects are automatically flushed to   the database with optimistic locks       But unlike Hibernate  SimpleORM uses a   very simple object structure and   architecture that avoids the need for   complex parsing  byte code processing   etc   SimpleORM is small and   transparent  packaged in two jars of   just 79K and 52K in size  with only   one small and optional dependency    Slf4j     Hibernate is over 2400K   plus about 2000K of dependent Jars      This makes SimpleORM easy to   understand and so greatly reduces   technical risk

User · Answer

Eclipse Link  for many reasons  but notably I feel like it has less bloat than other main stream solutions  at least less in-your-face bloat    Oh and Eclipse Link has been chosen to be the reference implementation for JPA 2 0

User · Answer

SimpleORM  because it is straight-forward and no-magic  It defines all meta data structures in Java code and is very flexible      SimpleORM provides similar   functionality to Hibernate by mapping   data in a relational database to Java   objects in memory   Queries can be   specified in terms of Java objects    object identity is aligned with   database keys  relationships between   objects are maintained and modified   objects are automatically flushed to   the database with optimistic locks       But unlike Hibernate  SimpleORM uses a   very simple object structure and   architecture that avoids the need for   complex parsing  byte code processing   etc   SimpleORM is small and   transparent  packaged in two jars of   just 79K and 52K in size  with only   one small and optional dependency    Slf4j     Hibernate is over 2400K   plus about 2000K of dependent Jars      This makes SimpleORM easy to   understand and so greatly reduces   technical risk

User · Answer

While I share the concerns regarding Java replacements for free-form SQL queries  I really do think people criticizing ORM are doing so because of a generally poor application design   True OOD is driven by classes and relationships  and ORM gives you consistent mapping of different relationship types and objects  If you use an ORM tool and end up coding query expressions in whatever query language the ORM framework supports  including  but not limited to Java expression trees  query methods  OQL etc    you are definitely doing something wrong  i e  your class model most likely doesn t support your requirements in the way it should  A clean application design doesn t really need queries on the application level  I ve been refactoring many projects people started out using an ORM framework in the same way as they were used to embed SQL string constants in their code  and in the end everyone was suprised about how simple and maintainable the whole application gets once you match up your class model with the usage model  Granted  for things like search functionality etc  you need a query language  but even then queries are so much constrained that creating an even complex VIEW and mapping that to a read-only persistent class is much nicer to maintain and look at than building expressions in some query language in the code of your application  The VIEW approach also leverages database capabilities and  via materialization  can be much better performance-wise than any hand-written SQL in your Java source  So  I don t see any reason for a non-trivial application NOT to use ORM

User · Answer

Eclipse Link  for many reasons  but notably I feel like it has less bloat than other main stream solutions  at least less in-your-face bloat    Oh and Eclipse Link has been chosen to be the reference implementation for JPA 2 0

User · Answer

Many ORM s are great  you need to know why you want to add abstraction on top of JDBC  I can recommend http   www jooq org to you  disclaimer  I m the creator of jOOQ  so this answer is biased   jOOQ embraces the following paradigm    SQL is a good thing  Many things can be expressed quite nicely in SQL  There is no need for complete abstraction of SQL  The relational data model is a good thing  It has proven the best data model for the last 40 years  There is no need for XML databases or truly object oriented data models  Instead  your company runs several instances of Oracle  MySQL  MSSQL  DB2 or any other RDBMS  SQL has a structure and syntax  It should not be expressed using  low-level  String concatenation in JDBC - or  high-level  String concatenation in HQL - both of which are prone to hold syntax errors  Variable binding tends to be very complex when dealing with major queries  THAT is something that should be abstracted  POJO s are great when writing Java code manipulating database data  POJO s are a pain to write and maintain manually  Code generation is the way to go  You will have compile-safe queries including datatype-safety  The database comes first  While the application on top of your database may change over time  the database itself is probably going to last longer  Yes  you do have stored procedures and user defined types  UDT s  in your legacy database  Your database-tool should support that    There are many other good ORM s  Especially Hibernate or iBATIS have a great community  But if you re looking for an intuitive  simple one  I ll say give jOOQ a try  You ll love it   -   Check out this example SQL        Select authors with books that are sold out   SELECT        FROM T AUTHOR a    WHERE EXISTS  SELECT 1                    FROM T BOOK                   WHERE T BOOK STATUS    SOLD OUT                      AND T BOOK AUTHOR ID   a ID     And how it can be expressed in jOOQ        Alias the author table   TAuthor a   T AUTHOR as  a          Use the aliased table in the select statement   create selectFrom a           whereExists create selectOne                               from T BOOK                              where T BOOK STATUS equal TBookStatus SOLD OUT                              and T BOOK AUTHOR ID equal a ID

User · Answer

Hibernate  because it s basically the defacto standard in Java and was one of the driving forces in the creation of the JPA  It s got excellent support in Spring  and almost every Java framework supports it  Finally  GORM is a really cool wrapper around it doing dynamic finders and so on using Groovy   It s even been ported to  NET  NHibernate  so you can use it there too

User · Answer

I would recommend using MyBatis   It is a thin layer on top of JDBC  it is very easy to map objects to tables and still use plain SQL  everything is under your control

User · Answer

Hibernate  because it s basically the defacto standard in Java and was one of the driving forces in the creation of the JPA  It s got excellent support in Spring  and almost every Java framework supports it  Finally  GORM is a really cool wrapper around it doing dynamic finders and so on using Groovy   It s even been ported to  NET  NHibernate  so you can use it there too

User · Answer

I had a really good experience with Avaje Ebean when I was writing a medium sized JavaSE application    It uses standard JPA annotations to define entities  but exposes a much simpler API  No EntityManager or any of that attached detached entities crap   It also lets you easily use SQL queries or event plain JDBC calls when necessary   It also has a very nice fluid and type-safe API for queries  You can write things like   List lt Person gt  boys   Ebean find Person class                                     where                                           eq  gender    M                                           le  age   18                                     orderBy  firstName                                      findList

User · Answer

I would recommend using MyBatis   It is a thin layer on top of JDBC  it is very easy to map objects to tables and still use plain SQL  everything is under your control

User · Answer

I have stopped using ORMs   The reason is not any great flaw in the concept  Hibernate works well  Instead  I have found that queries have low overhead and I can fit lots of complex logic into large SQL queries  and shift a lot of my processing into the database   So consider just using the JDBC package

User · Answer

SimpleORM  because it is straight-forward and no-magic  It defines all meta data structures in Java code and is very flexible      SimpleORM provides similar   functionality to Hibernate by mapping   data in a relational database to Java   objects in memory   Queries can be   specified in terms of Java objects    object identity is aligned with   database keys  relationships between   objects are maintained and modified   objects are automatically flushed to   the database with optimistic locks       But unlike Hibernate  SimpleORM uses a   very simple object structure and   architecture that avoids the need for   complex parsing  byte code processing   etc   SimpleORM is small and   transparent  packaged in two jars of   just 79K and 52K in size  with only   one small and optional dependency    Slf4j     Hibernate is over 2400K   plus about 2000K of dependent Jars      This makes SimpleORM easy to   understand and so greatly reduces   technical risk

User · Answer

I had a really good experience with Avaje Ebean when I was writing a medium sized JavaSE application    It uses standard JPA annotations to define entities  but exposes a much simpler API  No EntityManager or any of that attached detached entities crap   It also lets you easily use SQL queries or event plain JDBC calls when necessary   It also has a very nice fluid and type-safe API for queries  You can write things like   List lt Person gt  boys   Ebean find Person class                                     where                                           eq  gender    M                                           le  age   18                                     orderBy  firstName                                      findList

User · Answer

None  because having an ORM takes too much control away with small benefits  The time savings gained are easily blown away when you have to debug abnormalities resulting from the use of the ORM  Furthermore  ORMs discourage developers from learning SQL and how relational databases work and using this for their benefit

User · Answer

While I share the concerns regarding Java replacements for free-form SQL queries  I really do think people criticizing ORM are doing so because of a generally poor application design   True OOD is driven by classes and relationships  and ORM gives you consistent mapping of different relationship types and objects  If you use an ORM tool and end up coding query expressions in whatever query language the ORM framework supports  including  but not limited to Java expression trees  query methods  OQL etc    you are definitely doing something wrong  i e  your class model most likely doesn t support your requirements in the way it should  A clean application design doesn t really need queries on the application level  I ve been refactoring many projects people started out using an ORM framework in the same way as they were used to embed SQL string constants in their code  and in the end everyone was suprised about how simple and maintainable the whole application gets once you match up your class model with the usage model  Granted  for things like search functionality etc  you need a query language  but even then queries are so much constrained that creating an even complex VIEW and mapping that to a read-only persistent class is much nicer to maintain and look at than building expressions in some query language in the code of your application  The VIEW approach also leverages database capabilities and  via materialization  can be much better performance-wise than any hand-written SQL in your Java source  So  I don t see any reason for a non-trivial application NOT to use ORM

User · Answer

Hibernate  because it s basically the defacto standard in Java and was one of the driving forces in the creation of the JPA  It s got excellent support in Spring  and almost every Java framework supports it  Finally  GORM is a really cool wrapper around it doing dynamic finders and so on using Groovy   It s even been ported to  NET  NHibernate  so you can use it there too

User · Answer

I have stopped using ORMs   The reason is not any great flaw in the concept  Hibernate works well  Instead  I have found that queries have low overhead and I can fit lots of complex logic into large SQL queries  and shift a lot of my processing into the database   So consider just using the JDBC package

User · Answer

Hibernate  because it    is stable - being around for so many years  it lacks any major problems dictates the standards in the ORM field implements the standard  JPA   in addition to dictating it  has tons of information about it on the Internet  There are many tutorials  common problem solutions  etc is powerful - you can translate a very complex object model into a relational model  it has support for any major and medium RDBMS is easy to work with  once you learn it well   A few points on why  and when  to use ORM    you work with objects in your system  if your system has been designed well   Even if using JDBC  you will end up making some translation layer  so that you transfer your data to your objects  But my bets are that hibernate is better at translation than any custom-made solution  it doesn t deprive you of control  You can control things in very small details  and if the API doesn t have some remote feature - execute a native query and you have it  any medium-sized or bigger system can t afford having one ton of queries  be it at one place or scattered across   if it aims to be maintainable if performance isn t critical  Hibernate adds performance overhead  which in some cases can t be ignored

User · Answer

SimpleORM  because it is straight-forward and no-magic  It defines all meta data structures in Java code and is very flexible      SimpleORM provides similar   functionality to Hibernate by mapping   data in a relational database to Java   objects in memory   Queries can be   specified in terms of Java objects    object identity is aligned with   database keys  relationships between   objects are maintained and modified   objects are automatically flushed to   the database with optimistic locks       But unlike Hibernate  SimpleORM uses a   very simple object structure and   architecture that avoids the need for   complex parsing  byte code processing   etc   SimpleORM is small and   transparent  packaged in two jars of   just 79K and 52K in size  with only   one small and optional dependency    Slf4j     Hibernate is over 2400K   plus about 2000K of dependent Jars      This makes SimpleORM easy to   understand and so greatly reduces   technical risk

User · Answer

Hibernate  because it    is stable - being around for so many years  it lacks any major problems dictates the standards in the ORM field implements the standard  JPA   in addition to dictating it  has tons of information about it on the Internet  There are many tutorials  common problem solutions  etc is powerful - you can translate a very complex object model into a relational model  it has support for any major and medium RDBMS is easy to work with  once you learn it well   A few points on why  and when  to use ORM    you work with objects in your system  if your system has been designed well   Even if using JDBC  you will end up making some translation layer  so that you transfer your data to your objects  But my bets are that hibernate is better at translation than any custom-made solution  it doesn t deprive you of control  You can control things in very small details  and if the API doesn t have some remote feature - execute a native query and you have it  any medium-sized or bigger system can t afford having one ton of queries  be it at one place or scattered across   if it aims to be maintainable if performance isn t critical  Hibernate adds performance overhead  which in some cases can t be ignored

[java] What Java ORM do you prefer, and why?

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