Spring Boot 番外 (02) - 自定义Condition

// 给定环境下，该Bean定义是否符合条件
boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata);

public class WorldCondition implements Condition {

    static String WORLD_ID = "The World";

    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        // TODO 这里我们还没有定义注解，没有办法写检查条件的逻辑
    }
}

@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Conditional(WorldCondition.class) //HL
public @interface OnWorld {
    String value();
}

@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
    String world = metadata.getAnnotationAttributes(OnWorld.class.getName())
                           .get("value").toString();
    return WORLD_ID.equals(world);
}

public static void main(String[] args) {
    ConfigurableApplicationContext ctx1 = SpringApplication.run(Application.class, args);
    System.out.println(ctx1.getBean(BeanA.class));
    ctx1.close();

    WorldCondition.WORLD_ID = "Another World";

    ConfigurableApplicationContext ctx2 = SpringApplication.run(Application.class, args);
    System.out.println(ctx2.getBean(BeanA.class));
}

@Bean
@OnWorld("The World")
public static BeanA beanA1() {
    System.out.println("The world bean construct");
    return new BeanA();
}

@Bean
@OnWorld("Another World")
public static BeanA beanA2() {
    System.out.println("Another world bean construct");
    return new BeanA();
}

// 1
The world bean construct
BeanA{world='The World'}
// 2
Another world bean construct
BeanA{world='Another World'}