Question

I want to be able to call Interfaces in my class, but have spring instantiate them with the right implementation class behind the scenes.

I.e. Normally you can do:

IClass clz = new Class();

I want to have the line IClass clz; preferable in the middle of a method (or as one of the attributes if it can’t be done), where clz is instantiated to the class I want by Spring.

The reason I’d like to do it this way is because I want to be able to be able to change which implementation I want to use simply by editing the context files.

Even better, would be knowing how to do the above with class contructors that expect parameters. i.e. new Class(ar1, arg2);

I hope this makes sense. Any help would be much appreciated.

Answer 1

You can make your class implement BeanFactoryAware and then Spring will inject the bean factory in your class. If you then want to get an instance of a class implementing your interface you say something like:

beanFactory.getBean(IClass.class);

If there are multiple beans that implement the same interface you will have to resolve by name. To create a new object each time you ask this, set the bean scope of the bean you’re asking for to “prototype”.