ImprovedNamingStrategy no longer working in Hibernate 5

Thanks for posting your own solution. It helps me so much to set Hibernate 5 naming strategy!

The hibernate.ejb.naming_strategy property of pre-Hibernate 5.0 seems split into two parts:

• hibernate.physical_naming_strategy
• hibernate.implicit_naming_strategy

The values of these properties do not implement the NamingStrategy interface as did hibernate.ejb.naming_strategy. There are two new interfaces for these purposes:

• org.hibernate.boot.model.naming.PhysicalNamingStrategy
• org.hibernate.boot.model.naming.ImplicitNamingStrategy

Hibernate 5 provides only one implementation of PhysicalNamingStrategy (PhysicalNamingStrategyStandardImpl) that assumes physical identifier names are the same as logical ones.

There are several implementations of ImplicitNamingStrategy but I found none equivalent to the old ImprovedNamingStrategy. (See: org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyHbmImpl)

So, I implemented my own PhysicalNamingStrategy which is very simple:

public class PhysicalNamingStrategyImpl extends PhysicalNamingStrategyStandardImpl implements Serializable {

 public static final PhysicalNamingStrategyImpl INSTANCE = new PhysicalNamingStrategyImpl();

 @Override
 public Identifier toPhysicalTableName(Identifier name, JdbcEnvironment context) {
     return new Identifier(addUnderscores(name.getText()), name.isQuoted());
 }

 @Override
 public Identifier toPhysicalColumnName(Identifier name, JdbcEnvironment context) {
     return new Identifier(addUnderscores(name.getText()), name.isQuoted());
 }


 protected static String addUnderscores(String name) {
     final StringBuilder buf = new StringBuilder( name.replace('.', '_') );
     for (int i=1; i<buf.length()-1; i++) {
        if (
             Character.isLowerCase( buf.charAt(i-1) ) &&
             Character.isUpperCase( buf.charAt(i) ) &&
             Character.isLowerCase( buf.charAt(i+1) )
         ) {
             buf.insert(i++, '_');
         }
     }
     return buf.toString().toLowerCase(Locale.ROOT);
 }
}

Note that the addUnderscores() method is from the original org.hibernate.cfg.ImprovedNamingStrategy.

Then, I set this physical strategy into the persistence.xml file :

  <property name="hibernate.physical_naming_strategy" value="my.package.PhysicalNamingStrategyImpl" />

It is a trap to set Hibernate 5 naming strategy as previous version settings.