@Configuration 标注在类上，相当于把该类作为 spring 的 xml 配置文件中的 <beans>，作用为：配置 spring 容器（context）
package com.test.spring.support.configuration;
@Configuration
public class TestConfiguration {
public TestConfiguration(){
System.out.println("spring 容器启动初始化......");
}
}
相当于
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:util="http://www.springframework.org/schema/util" xmlns:task="http://www.springframework.org/schema/task" xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.0.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd
http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.0.xsd" default-lazy-init="false">
</beans>
测试
package com.test.spring.support.configuration;
public class TestMain {
public static void main(String[] args) {
//@Configuration 注解的 spring 容器加载方式，用 AnnotationConfigApplicationContext 替换 ClassPathXmlApplicationContext
ApplicationContext context = new AnnotationConfigApplicationContext(TestConfiguration.class);
// 如果加载 spring-context.xml 文件：
//ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
}
}