根据official doc：
Annotation Type Configuration
Indicates that a class declares one or more @Bean methods and may be
processed by the Spring container to generate bean definitions…
@Configuration classes may be composed using the @Import annotation,
not unlike the way that works in Spring XML. Because
@Configuration objects are managed as Spring beans within the
container..
但我也可以在没有@Import的情况下使用@Configuration注释.我已经测试了下面列出的代码,它按预期工作.那么使用@Import的目的是什么？
DispatcherServletInitializer
public class ApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class
WebMvcConfigurerAdapter
@Configuration
@EnableWebMvc
@ComponentScan(basePackages = { "package.name" })
// @Import(OptionalConfig.class)
public class WebConfig extends WebMvcConfigurerAdapter {
// ...
}
OptionalConfig
@Configuration
public class OptionalConfig {
@Bean(name = "myClass")
public MyClass myClass() {
return new MyClass();
}
}
服务
@Service
public class MyServiceImpl implements MyService {
@Autowired
private MyClass myClass; // yes,it works
// ...
}
Thus far,we’ve seen how to break up bean definitions into multiple @Configuration classes and how to reference those beans across @Configuration boundaries. These scenarios have required providing all @Configuration classes to the constructor of a JavaConfigApplicationContext,and this is not always ideal. Often it is preferable to use an aggregation approach,where one @Configuration class logically imports the bean definitions defined by another.
The @Import annotation provides just this kind of support,and it is the direct equivalent of the element found in Spring beans XML files.
http://docs.spring.io/spring-javaconfig/docs/1.0.0.M4/reference/html/ch04s03.html
