Hibernate annotation or XML configuration

Question

I have started a new project with Hibernate. Is Hibernate annotation a better choice or is Hibernate XML mapping better?

I have used Hibernate with XML configuration, but I have no idea about annotation.

1. are there any issues while going for annotation based implementation?
2. is maintenance of an application easier or more complicated with annotation based?
3. which one is better (that is, annotation or XML mapping) and which one is is widely used? Why?
4. If I use a different database at a different level, that is, production or integration or development level, do I need to go for change of code?

Note: I am not comparing two technologies, but I want to know which one (that is, out of two ways) to be used in the application with the latest technology.

Answer 1

Annotations are a better choice for a new application, since it makes the application free from XML files. It is also less code and maintenance is easy. It also helps for refactoring the application (with IDE like Eclipse/NetBeans, etc.), which is the problem with XML since you need to change it manually.

Answers:

1. No issues, you can use the latest JSR 330 API (dependency injection for Java) which helps to the same annotation for a JSF managed bean (use @Named instead of @managedbean), the Spring IoC layer and Hibernate, so that whole layer you will have a single annotation concept instead of a framework specific.

2. Maintenance is easy especially refactoring of code, fewer or no XML files and new learning. Use JPA based annotation with Hibernate. You can find some sample in google.

3. Widely use XML based since it was there from begining, but for a new application annotation is better which is more mature.

4. For change to any database, the code will remain the same in annotation or XML, only you need to change the property file values.