Spring对Java配置的支持是由@Configuration注解和@Bean注解来实现的。由@Bean注解的方法将会实例化、配置和初始化一个新对象，这个对象将由Spring的IoC容器来管理。@Bean声明所起到的作用与<bean/> 元素类似。被@Configuration所注解的类则表示这个类的主要目的是作为bean定义的资源。被@Configuration声明的类可以通过在同一个类的内部调用@bean方法来设置嵌入bean的依赖关系。
最简单的@Configuration 声明类请参考下面的代码：
@Configuration
public class AppConfig
{
@Bean
public MyService myService() {
return new MyServiceImpl();
}
}对于上面的@Beans配置文件相同的XML配置文件如下：
<beans>
<bean id="myService" class="com.howtodoinjava.services.MyServiceImpl"/>
</beans>
上述配置方式的实例化方式如下：利用AnnotationConfigApplicationContext 类进行实例化
public static void main(String[] args) {
ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
MyService myService = ctx.getBean(MyService.class);
myService.doStuff();
}要使用组件组建扫描，仅需用@Configuration进行注解即可：
@Configuration
@ComponentScan(basePackages = "com.howtodoinjava")
public class AppConfig {
...
}在上面的例子中，com.acme包首先会被扫到，然后再容器内查找被@Component 声明的类，找到后将这些类按照Sring bean定义进行注册。
如果你要在你的web应用开发中选用上述的配置的方式的话，需要用AnnotationConfigWebApplicationContext 类来读取配置文件，可以用来配置Spring的Servlet监听器ContrextLoaderListener或者Spring MVC的DispatcherServlet。
<web-app>
<!-- Configure ContextLoaderListener to use AnnotationConfigWebApplicationContext instead of the default XmlWebApplicationContext -->
<context-param>
<param-name>contextClass</param-name>
<param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
</context-param>
<!-- Configuration locations must consist of one or more comma- or space-delimited fully-qualified @Configuration classes. Fully-qualified packages may also be specified for component-scanning -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>com.howtodoinjava.AppConfig</param-value>
</context-param>
<!-- Bootstrap the root application context as usual using ContextLoaderListener -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- Declare a Spring MVC DispatcherServlet as usual -->
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!-- Configure DispatcherServlet to use AnnotationConfigWebApplicationContext instead of the default XmlWebApplicationContext -->
<init-param>
<param-name>contextClass</param-name>
<param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
</init-param>
<!-- Again, config locations must consist of one or more comma- or space-delimited and fully-qualified @Configuration classes -->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>com.howtodoinjava.web.MvcConfig</param-value>
</init-param>
</servlet>
<!-- map all requests for /app/* to the dispatcher servlet -->
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/app/*</url-pattern>
</servlet-mapping>
</web-app>
