How to make Spring to pick a subclass in a property reference?

Question

I am trying to use a specialized subclass in a Spring web application for testing.

The application context xml files reference a class in a few bean's properties by the fully qualified class name, like this:

<bean id="blahblah" class="x.y.z.Blah">
   <property name="myFooAttribute" ref="x.y.z.Foo"/>
</bean>

and I would like to instantiate and use x.y.z.Bar instead of x.y.z.Foo, everywhere it is used.

In my test I am using a Java based config and importing the XML configuration (legacy stuff that I don't really want to mess too much around) since it feels more natural when I'm going to be patching things and using mocks declared inline.

@Configuration
@ImportResource({
        "classpath:applicationContext-common.xml",
        "classpath:app-servlet.xml"
})
static class TestConfig {
    static class Bar extends Foo {
        //some stuff overridden here
    }

}

How can I make all the places that reference to x.y.z.Foo use my Bar class instead? Preferably without changing the xml files...

Answer 1

Creating a bean named as the class that you are trying to override works. It can be achieved in the Java style configuration using the Bean annotation.

@Configuration
@ImportResource({
        "classpath:applicationContext-common.xml",
        "classpath:app-servlet.xml"
})
static class TestConfig {
    static class Bar extends Foo {
        //some stuff overridden here
    }
    private Bar myTestBar = new Bar();
    @Bean(name="x.y.z.Foo")
    public Foo getFoo() {
       return myTestBar;
    }
}