SPRING IN ACTION 第4版笔记-第一章-004-用类来管理DI

一、

1.

package chapter01.sia.knights.config;

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

import chapter01.sia.knights.BraveKnight;
import chapter01.sia.knights.Knight;
import chapter01.sia.knights.Quest;
import chapter01.sia.knights.SlayDragonQuest;

@Configuration
public class KnightConfig {

  @Bean
  public Knight knight() {
    return new BraveKnight(quest());
  }
  
  @Bean
  public Quest quest() {
    return new SlayDragonQuest(System.out);
  }

}

解析：

(1)public Knight knight() {

return new BraveKnight(quest());
}　　说明new knight时用BraveKnight

(2)@Bean

public Quest quest() {
return new SlayDragonQuest(System.out);
}　　说明new quest时用SlayDragonQuest

package chapter01.sia.knights;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class KnightMain {

  public static void main(String[] args) throws Exception {
    //ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:knight.xml");
    //ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:minstrel.xml");
    ApplicationContext context = new AnnotationConfigApplicationContext(
            chapter01.sia.knights.config.KnightConfig.class);
    Knight knight = context.getBean(Knight.class);
    knight.embarkOnQuest();
    //context.close();
  }

}

运行

Embarking on quest to slay the dragon!