在實際開發中經常會遇到在spring容器加載完某個bean之後,需要執行一些業務代碼的場景。比如初始化配置、緩存等。有以下幾種方式可以實現此需求(歡迎補充)
實現ApplicationListener接口
實現ApplicationListener接口並實現方法onApplicationEvent()方法,Bean在創建完成後會執行onApplicationEvent方法
@Component
public class DoByApplicationListener implements ApplicationListener<ContextRefreshedEvent> {
public DoByApplicationListener() {
System.out.println("DoByApplicationListener constructor");
}
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
if (event.getApplicationContext().getParent() == null) {
System.out.println("DoByApplicationListener do something");
}
}
}
實現InitializingBean接口
實現InitializingBean接口並實現方法afterPropertiesSet(),Bean在創建完成後會執行afterPropertiesSet()方法
@Component
public class DoByInitializingBean implements InitializingBean {
public DoByInitializingBean() {
System.out.println("DoByInitializingBean constructor");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("InitByInitializingBean do something");
}
}
使用@PostConstruct註解
在Bean的某個方法上使用@PostConstruct註解,Bean在創建完成後會執行該方法
@Component
public class DoByPostConstructAnnotation {
public DoByPostConstructAnnotation() {
System.out.println("DoByPostConstructAnnotation constructor");
}
@PostConstruct
public void init(){
System.out.println("InitByPostConstructAnnotation do something");
}
}
使用init-method
使用init-metod可以指定Bean在創建完成後,初始化使用的方法,比如有個Bike類
public class Bike {
public Bike() {
System.out.println("Bike constructor");
}
public void initBike() {
System.out.println("Bike do something");
}
}
使用@Configuration註解來啓動容器,並設置Bike的初始化方法爲initBike
@Configuration
public class DoByInitMethod {
@Bean(initMethod ="initBike")
public Bike bike() {
return new Bike();
}
}
以上方式和代碼全部都測試運行過,絕對可用!