@order注解 解答

注解@Order或者接口Ordered的作用是定义Spring IOC容器中Bean的执行顺序的优先级，而不是定义Bean的加载顺序，Bean的加载顺序不受@Order或Ordered接口的影响；

注解源码解读：

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD, ElementType.FIELD})
@Documented
public @interface Order {

	/**
	 * 默认是最低优先级,值越小优先级越高
	 */
	int value() default Ordered.LOWEST_PRECEDENCE;

}

示例代码:

package com.runlion.tms.admin.constant;

public class AService {

}
package com.runlion.tms.admin.constant;

public class BService {

}

package com.runlion.tms.admin.constant;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;

@Configuration
@Order(2)
public class AConfig {
  @Bean
  public AService AService() {
    System.out.println("AService 加载了");
    return new AService();
  }

}
package com.runlion.tms.admin.constant;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;

@Configuration
@Order(1)
public class BConfig {
  @Bean
  public BService bService() {
    System.out.println("BService 加载了");
    return new BService();
  }
}

package com.runlion.tms.admin.constant;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class OrderMain {
  public static void main(String[] args) {
    AnnotationConfigApplicationContext context =
        new AnnotationConfigApplicationContext("com.runlion.tms.admin.constant");
  }
}