Guice子喷射器覆盖绑定

Question

我试图覆盖已在基本注入器中配置的子注入器中的绑定.

像那样 :

public class PersistenceModule extends Abstract{

    @Override
    protected void configure() {
        bind(IProductPersistenceHelper.class).to(ProductPersistenceHelper.class);
    }
}

然后 :

Injector injector = Guice.createInjector(new PersistenceModule());
injector.createChildInjector(new AbstractModule(){
        @Override
        protected void configure() {
            bind(IProductPersistenceHelper.class).to(MockProductPersistenceHelper.class);
        }

})

Guice抱怨它已经具有约束力.该问题是否有任何模式或最佳实践？