In contrast, the lifecycle of a bean in a Spring container is more elaborate. It’s
important to understand the lifecycle of a Spring bean, because you may want to take
advantage of some of the opportunities that Spring offers to customize how a bean is
created. Figure 1.5 shows the startup lifecycle of a typical bean as it’s loaded into a
Spring application context.
As you can see, a bean factory performs several setup steps before a bean is ready to
use. Let’s break down figure 1.5 in more detail:
1 Spring instantiates the bean.
2 Spring injects values and bean references into the bean’s properties.
3 If the bean implements BeanNameAware, Spring passes the bean’s ID to the set-
BeanName() method.
4 If the bean implements BeanFactoryAware, Spring calls the setBeanFactory()
method, passing in the bean factory itself.
5 If the bean implements ApplicationContextAware, Spring calls the set-
ApplicationContext() method, passing in a reference to the enclosing application
context.
6 If the bean implements the BeanPostProcessor interface, Spring calls its post-
ProcessBeforeInitialization() method.
7 If the bean implements the InitializingBean interface, Spring calls its after-
PropertiesSet() method. Similarly, if the bean was declared with an initmethod,
then the specified initialization method is called.
8 If the bean implements BeanPostProcessor, Spring calls its postProcess-
AfterInitialization() method.
9 At this point, the bean is ready to be used by the application and remains in the
application context until the application context is destroyed.
10 If the bean implements the DisposableBean interface, Spring calls its
destroy() method. Likewise, if the bean was declared with a destroy-method,
the specified method is called.
Now you know how to create and load a Spring container. But an empty container
isn’t much good by itself; it doesn’t contain anything unless you put something in it.
To achieve the benefits of Spring DI, you must wire your application objects into the
Spring container. We’ll go into bean wiring in more detail in chapter 2.
参考文献
Spring in Action