This method allows the bean instance to perform validation of its overall
* configuration and final initialization when all bean properties have been set.
* @throws Exception in the event of misconfiguration (such as failure to set an
* essential property) or if initialization fails for any other reason
*/
void afterPropertiesSet() throws Exception;
}
```
* DisposableBean
```java
public interface DisposableBean {
/**
* Invoked by the containing {@code BeanFactory} on destruction of a bean.
* @throws Exception in case of shutdown errors. Exceptions will get logged
* but not rethrown to allow other beans to release their resources as well.
*/
void destroy() throws Exception;
}
```
* 예제 클래스
```java
package dh0023.springcore.lifecycle;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
/**
* 테스트를 위한 가짜 NetworkClient
*/
public class NetworkClient implements InitializingBean, DisposableBean {
private String url;
public NetworkClient() {
System.out.println("생성자 호출, url = " + url);
}
public void setUrl(String url) {
this.url = url;
}
// start service
public void connect() {
System.out.println("connect: " + url);
}
public void call(String message) {
System.out.println("call: " + url + " message = " + message);
}
public void disconnect() {
System.out.println("close: " + url);
}
/**
* 의존관계 주입 후 호출
* @throws Exception
*/
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("NetworkClient.afterPropertiesSet");
connect();
call("초기화 연결 메세지");
}
/**
* 소멸직후 콜백
* @throws Exception
*/
@Override
public void destroy() throws Exception {
System.out.println("NetworkClient.destroy");
disconnect();
}
}
```
* Test Code
```java
package dh0023.springcore.lifecycle;
import org.junit.jupiter.api.Test;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Description;
public class BeanLifeCycleTest {
@Test
@Description("인터페이스 적용 테스트")
void lifeCycleInterfaceTest() {
ConfigurableApplicationContext ac = new AnnotationConfigApplicationContext(LifeCycleConfig.class);
NetworkClient client = ac.getBean(NetworkClient.class);
ac.close();
}
@Configuration
static class LifeCycleConfig {
@Bean
public NetworkClient networkClient() {
NetworkClient networkClient = new NetworkClient();
networkClient.setUrl("http://spring-core.dev");
return networkClient;
}
}
}
```
* 결과
```
23:23:39.553 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'networkClient'
생성자 호출, url = null
NetworkClient.afterPropertiesSet
connect: http://spring-core.dev
call: http://spring-core.dev message = 초기화 연결 메세지
23:23:39.645 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@932bc4a, started on Sun May 16 23:23:38 KST 2021
NetworkClient.destroy
close: http://spring-core.dev
Process finished with exit code 0
```
1. Creating shared instance of singleton bean 'networkClient'
2. 생성자 호출
3. NetworkClient.afterPropertiesSet
4. Closing org.springframework.context.annotation.AnnotationConfigApplicationContext\@932bc4a
5. NetworkClient.destroy
6. 스프링 종료
다음과 같은 순서로 사이클이 수행되는 것을 확인할 수 있다.
#### 단점
* 스프링 전용 인터페이스이다. 해당 코드가 스프링 전용 인터페이스에 의존하게 된다.
* 초기화, 소멸 메서드의 이름을 변경할 수 없다.
* 외부 라이브러리에 적용할 수 없다.
이 방법은 초창기 나온 방법으로, 현재는 거의 사용하지 않는다.
### 설정 정보 사용(메서드 등록)
`@Bean` 어노테이션에 등록 초기화, 소멸 메서드를 설정하는 방법이다.
* 예제 클래스
```java
/**
* 테스트를 위한 가짜 NetworkClient
*/
public class NetworkClientMethod {
private String url;
public NetworkClientMethod() {
System.out.println("생성자 호출, url = " + url);
}
public void setUrl(String url) {
this.url = url;
}
// start service
public void connect() {
System.out.println("connect: " + url);
}
public void call(String message) {
System.out.println("call: " + url + " message = " + message);
}
public void disconnect() {
System.out.println("close: " + url);
}
public void init() {
System.out.println("NetworkClientMethod.init");
connect();
call("초기화 연결 메세지");
}
public void close() {
System.out.println("NetworkClientMethod.close");
disconnect();
}
}
```
* 테스트 코드
```java
package dh0023.springcore.lifecycle;
import org.junit.jupiter.api.Test;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Description;
public class BeanLifeCycleTest {
@Test
@Description("메서드 적용 테스트")
void lifeCycleMethodTest() {
ConfigurableApplicationContext ac = new AnnotationConfigApplicationContext(LifeCycleConfig.class);
NetworkClientMethod client = ac.getBean(NetworkClientMethod.class);
ac.close();
}
@Configuration
static class LifeCycleConfig {
@Bean(initMethod = "init", destroyMethod = "close")
public NetworkClientMethod networkClientMethod() {
NetworkClientMethod networkClientMethod = new NetworkClientMethod();
networkClientMethod.setUrl("http://spring-core.dev");
return networkClientMethod;
}
}
}
```
* 결과
```java
23:35:00.964 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'networkClientMethod'
생성자 호출, url = null
NetworkClientMethod.init
connect: http://spring-core.dev
call: http://spring-core.dev message = 초기화 연결 메세지
23:35:01.128 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@932bc4a, started on Sun May 16 23:35:00 KST 2021
NetworkClientMethod.close
close: http://spring-core.dev
Process finished with exit code 0
```
1. Creating shared instance of singleton bean 'networkClientMethod'
2. 생성자 호출
3. 초기화 콜백 : NetworkClientMethod.init
4. Closing org.springframework.context.annotation.AnnotationConfigApplicationContext\@932bc4a
5. 소멸직후 콜백 : NetworkClientMethod.close
6. 스프링 종료
#### 특징
* 메서드 이름을 자유롭게 줄 수 있다.
* 스프링 빈이 스프링 코드에 의존하지 않는다.
* 설정 정보를 사용하기 때문에 코드를 고칠 수 없는 외부 라이브러리에도 초기화, 종료 메서드를 적용할 수 있다.
#### @Bean destroyMethod
라이브러리 대부분 `close`, `shutdown` 과 같은 이름의 종료 메서드를 사용한다.
```java
String destroyMethod() default AbstractBeanDefinition.INFER_METHOD;
```
```java
public static final String INFER_METHOD = "(inferred)";
```
`destoryMethod()` 의 default값은 `(inferred)` 로 등록되어 있다. 이 추론 기능은 `close`, `shutdown` 과 같은 이름의 메서드를 자동으로 호출해준다. 이름 그대로 종료 메서드를 추론해서 호출해주는 것이다.
따라서 직접 스프링 빈으로 등록하면 종료 메서드는 따로 적어주지 않아도 된다. 만약 추론기능을 사용하기 싫은 경우에는 `destroyMethod=""` 로 설정해주면 된다.
### 어노테이션 방법
* `@PostConstruct`
```java
package javax.annotation;
import java.lang.annotation.*;
import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;
/**
* The PostConstruct annotation is used on a method that
* needs to be executed after dependency injection is done to perform
* any initialization. This method must be invoked before the class
* is put into service. This annotation must be supported on all classes
* that support dependency injection. The method annotated with
* PostConstruct must be invoked even if the class does
* not request any resources to be injected. Only one
* method in a given class can be annotated with this annotation.
* The method on which the PostConstruct annotation is
* applied must fulfill all of the following criteria:
*
InvocationContext
* object as defined by the Interceptors specification.* void <METHOD>(InvocationContext) *
* Object <METHOD>(InvocationContext) throws Exception *
* Note: A PostConstruct interceptor method must not throw application * exceptions, but it may be declared to throw checked exceptions including * the java.lang.Exception if the same interceptor method interposes on * business or timeout methods in addition to lifecycle events. If a * PostConstruct interceptor method returns a value, it is ignored by * the container. *
* void <METHOD>() *
PostConstruct annotation
* is applied may be public, protected, package private or private.PreDestroy annotation is used on a method as a
* callback notification to signal that the instance is in the
* process of being removed by the container. The method annotated
* with PreDestroy is typically used to
* release resources that it has been holding. This annotation must be
* supported by all container-managed objects that support the use of
* the PostConstruct annotation except the Jakarta EE application
* client. The method on which the PreDestroy annotation
* is applied must fulfill all of the following criteria:
* InvocationContext
* object as defined by the Interceptors specification.* void <METHOD>(InvocationContext) *
* Object <METHOD>(InvocationContext) throws Exception *
* Note: A PreDestroy interceptor method must not throw application * exceptions, but it may be declared to throw checked exceptions including * the java.lang.Exception if the same interceptor method interposes on * business or timeout methods in addition to lifecycle events. If a * PreDestroy interceptor method returns a value, it is ignored by * the container. *
* void <METHOD>() *