使用方式
直接注入
新建一個Man類,不加註解,不在啓動時注入到spring IOC容器中
public class Man {
public void say() {
System.out.println("I am a man.");
}
}
新建一個Woman類,不加註解,不在啓動時注入到spring IOC容器中
public class Woman {
public void say() {
System.out.println("I am a woman.");
}
}
在啓動類中用@Import注入Man.class和Woman.class
@SpringBootApplication
@Import({Man.class, Woman.class})
public class AddApplication {
public static void main(String[] args) {
ConfigurableApplicationContext context = SpringApplication.run(AddApplication.class, args);
Man man = context.getBean(Man.class);
Woman woman = context.getBean(Woman.class);
man.say();
woman.say();
}
}
得到輸出結果
2019-09-04 16:01:38.836 INFO 23088 --- [ restartedMain] c.p.a.AddApplication : Started AddApplication in 13.614 seconds (JVM running for 15.87)
I am a man.
I am a woman.
可以看到這個註解可以讓這個類的實例不需要在啓動的時候注入,而是在運行中實際需要用到時開始注入。
使用配置類
創建一個配置類,類上面不需要加註解,但是獲取Man和Woman的方法要加@Bean註解注入
public class HumanConfig {
@Bean
public Man getMan() {
return new Man();
}
@Bean
public Woman getWoman() {
return new Woman();
}
}
在啓動類中用@Import注入HumanConfig.class
@SpringBootApplication
@Import({HumanConfig.class})
public class AddApplication {
public static void main(String[] args) {
ConfigurableApplicationContext context = SpringApplication.run(AddApplication.class, args);
Man man = context.getBean(Man.class);
Woman woman = context.getBean(Woman.class);
man.say();
woman.say();
}
}
得到輸出結果
2019-09-04 16:09:03.368 INFO 21892 --- [ restartedMain] c.p.a.AddApplication : Started AddApplication in 13.614 seconds (JVM running for 15.87)
I am a man.
I am a woman.
通過配置類的好處就是可用統一入口,方便查找資源和注入時使用的方便