Spring Note 8:JavaConfig

The central artifacts in Spring’s new Java-configuration support are @Configuration-annotated classes and @Bean-annotated methods.
The @Bean annotation is used to indicate that a method instantiates, configures, and initializes a new object to be managed by the Spring IoC container. For those familiar with Spring’s<beans/> XML configuration, the @Bean annotation plays the same role as the <bean/> element. You can use @Bean-annotated methods with any Spring @Component. However, they are most often used with @Configuration beans.
Annotating a class with @Configuration indicates that its primary purpose is as a source of bean definitions. Furthermore, @Configuration classes let inter-bean dependencies be defined by calling other @Bean methods in the same class.

使用Config开发可以省略配置文件。
LiuConfig.java:

// 这个也会被Spring容器托管，注册到容器中，因为它本来就是一个@Component
// @Configuration代表这是一个配置类，就和之前的Beans.xml一样
@Configuration
public class LiuConfig {

//    注册一个bean，相当于之前写的一个bean标签
//    方法的名字就相当于bean标签的id属性
//    方法的返回值，就相当于bean标签中的class属性
    @Bean
    public User user() {
        return new User();
    }
}

User.java:

@Component
public class User {
    @Value("XLIU")
    private String name;

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                '}';
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

MyTest.java:

public class MyTest {
    public static void main(String[] args) {
//        如果完全使用了配置类方法去做，我们就只能通过AnnotationConfig上下文来获取容器，通过配置类的class对象加载
       ApplicationContext applicationContext = new AnnotationConfigApplicationContext(LiuConfig.class);
       User user = applicationContext.getBean("user", User.class);
        System.out.println(user.getName());
    }
}