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.somnus.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.somnus")
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AnnotationConfigWeb ApplicationContext 类来读取配置文件，可以用来配置Spring的Servlet监听器ContextLoaderListener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>