@Qualifier Change of Behavior 4.0 Vs 3.x with Qualified Bean in Parent Context [SPR-10966] #15594
Description
Gary Russell opened SPR-10966 and commented
I don't know if this is a bug in 4.0 or 3.x; I suspect the latter but there is probably an argument for the former...
This was discovered when moving XD to Spring 4.0.0.M3.
In 4.0, an @Qualifier in a child context is not resolved to a <qualifier/> bean in a parent context, unless the parent context has <context:annotation-config/>.
Consider the following
child-context.xml
<context:component-scan base-package="foo" />
and
parent-context.xml
<bean id="foo" class="foo.BrokenQualifier$BarImpl">
<constructor-arg value="foo" />
<qualifier value="baz" />
</bean>
<bean id="bar" class="foo.BrokenQualifier$BarImpl">
<constructor-arg value="bar" />
</bean>
and
package foo;
public class BrokenQualifier {
public static void main(String[] args) {
ApplicationContext parent = new ClassPathXmlApplicationContext("parent-context.xml", BrokenQualifier.class);
ClassPathXmlApplicationContext child = new ClassPathXmlApplicationContext(parent);
child.setConfigLocation("foo/child-context.xml");
child.refresh();
System.out.println(child.getBean(Baz.class).getFoo());
child.close();
}
@Component
public static class Baz {
private final String foo;
@Autowired
public Baz(@Qualifier("baz") Bar aBar) {
this.foo = aBar.getBar();
}
public String getFoo() {
return foo;
}
}
public interface Bar {
public String getBar();
}
public static class BarImpl implements Bar {
private final String bar;
public BarImpl(String bar) {
this.bar = bar;
}
@Override
public String getBar() {
return bar;
}
}
}
Notice that the Baz constructor has an Qualifier matching the <qualifier/> in the parent context. All works fine with 3.x; with 4.0, we get
No qualifying bean of type [foo.BrokenQualifier$Bar] is defined: expected single matching bean but found 2: foo,bar
Adding <context:annotation-config/> to the parent context makes it work (as does changing the constructor parameter name from 'aBar' to 'foo').
Affects: 4.0 M3
Referenced from: commits eb1b3c5