Interview Questions: Spring IoC Container
June 11, 2013
| Qns-1: Which packages is the basis of Spring IoC container? |
| Ans: a. org.springframework.beans b. org.springframework.context |
| Qns-2: What is the role of BeanFactory in Spring IoC container? |
| Ans: BeanFactory provides the configuration mechanism so that any type of object can be managed easily. |
| Qns-3: What is the role of ApplicationContext in Spring IoC container? |
| Ans: ApplicationContext extends BeanFactory. ApplicationContext helps to integrate other module like Spring AOP, messages resource , event publication, application-layer specific contexts. |
| Qns-4: How can we instantiate ApplicationContext in standalone application? |
| Ans: We need to call ClassPathXmlApplicationContext or FileSystemXmlApplicationContext. |
| Qns-5: What are the variants of dependency Injection? |
|
Ans: There are two variants of Dependency Injection. a. Constructor-based dependency injection b. Setter-based dependency injection |
| Qns-6: What are disadvantages of autowiring in Spring? |
|
Ans: a. We cannot autowire primitives dat type, String and Classes. b. Autowiring is not so exact as explicit wiring. c. Autowiring will not be available for those tools that will generate documentation. |
| Qns-7: How many beans scopes are there in Spring IoC Container? |
|
Ans: There are five Bean scopes. a. Singleton b. Prototype c. Request d. Session e. Global Session |
| Qns-8: How to customize the nature of a bean? |
|
Ans:
a. Lifecycle callbacks can be customized by implementing interface InitializingBean and DisposableBean. b. Startup and shutdown callbacks can be customized by implementing interface Lifecycle. c. Use ApplicationContextAware and BeanNameAware. |
| Qns-9: What is the role of BeanPostProcessor Interface? |
| Ans: Implementing BeanPostProcessor interface, we can write our own bean instantiation logic. |
| Qns-10: What is the role of PropertyPlaceholderConfigurer in spring? |
| Ans: PropertyPlaceholderConfigurer externalize property values from a bean definition to another separate file. |