SPRING IN ACTION 第4版笔记-第一章-004-用类来管理DI
一、
1.
1 package chapter01.sia.knights.config; 2 3 import org.springframework.context.annotation.Bean; 4 import org.springframework.context.annotation.Configuration; 5 6 import chapter01.sia.knights.BraveKnight; 7 import chapter01.sia.knights.Knight; 8 import chapter01.sia.knights.Quest; 9 import chapter01.sia.knights.SlayDragonQuest; 10 11 @Configuration 12 public class KnightConfig { 13 14 @Bean 15 public Knight knight() { 16 return new BraveKnight(quest()); 17 } 18 19 @Bean 20 public Quest quest() { 21 return new SlayDragonQuest(System.out); 22 } 23 24 }
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
1 package chapter01.sia.knights; 2 3 import org.springframework.context.ApplicationContext; 4 import org.springframework.context.annotation.AnnotationConfigApplicationContext; 5 6 public class KnightMain { 7 8 public static void main(String[] args) throws Exception { 9 //ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:knight.xml"); 10 //ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:minstrel.xml"); 11 ApplicationContext context = new AnnotationConfigApplicationContext( 12 chapter01.sia.knights.config.KnightConfig.class); 13 Knight knight = context.getBean(Knight.class); 14 knight.embarkOnQuest(); 15 //context.close(); 16 } 17 18 }
运行
Embarking on quest to slay the dragon!
You can do anything you set your mind to, man!