Spring IoC and Generic Interface Type [duplicate] Spring IoC and Generic Interface Type [duplicate] spring spring

Spring IoC and Generic Interface Type [duplicate]


I do not believe this is possible due to erasure. We generally switched to strongly typed sub-interfaces when going for full-autowiring:

public interface LongService extends ISimpleService<Long> {}public interface StringService extends ISimpleService<String> {}

Upon doing this switch we found we actually liked this pretty well, because it allows us to do "find usage" tracking much better, something you loose with the generics interfaces.


i don't think thats possible without Qualifier

ill try to show my Solutions with a genericDAO, sorry if it's a bit detailed

the Interface and Implementation Class Definition

public interface GenericDAO<T, ID extends Serializable> (...)public class GenericDAOImpl<T, ID extends Serializable>    implements GenericDAO<T, ID>     (...) important is this constructor    public GenericDAOImpl(Class<T> persistentClass) {       this.persistentClass = persistentClass;    }

the spring bean definition, notice the abstract="true"

<bean id="genericHibernateDAO" class="de.optimum24.av.pers.ext.hibernate.dao.GenericDAOImpl"      abstract="true">    <description>        <![CDATA[            Definition des GenericDAO.        ]]>    </description>    <property name="sessionFactory" ref="sessionFactory" /></bean>

Using this genericDAO without special implementation Class

 <bean id="testHibernateChildDao" class="de.optimum24.av.pers.ext.hibernate.dao.GenericDAOImpl">    <property name="sessionFactory" ref="sessionFactory" />    <constructor-arg>        <value>de.optimum24.av.pers.test.hibernate.domain.TOChild</value>    </constructor-arg></bean>

notice the constructor-arg with an concrete Class, if you work with Spring Annotation you need to do:

@Autowired@Qualifier(value = "testHibernateChildDao")private GenericDAO<TOChild, Integer> ToChildDAO;

to distinguish the various versions of genericDao Beans (notice the Qualifier with direct Reference to the Beanname)

Using this genericDAO with special implementation Class

the Interface and Class

public interface TestHibernateParentDAO extends GenericDAO<TOParent, Integer>{  void foo();}public class TestHibernateParentDAOImpl extends GenericDAOImpl<TOParent, Integer>                              implements TestHibernateParentDAO {  @Override  public void foo() {      //* no-op */  }}

the Bean Definition, notice the "parent" Reference to the abstract genericDAO above

<bean id="testHibernateParentDao" class="de.optimum24.av.pers.test.hibernate.dao.TestHibernateParentDAOImpl"      parent="genericHibernateDAO" />

and usage with Spring Annotation

@Autowiredprivate TestHibernateParentDAO ToParentDAO;


It is possible to do this with erasure, if the generic type is fully reified at compile-time. In this case the type information is available via either of:

Class#getGenericInterfaces()Class#getGenericSuperclass()

This is the major feature of Guice which is missing from Spring.