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[英]How to autowire this dependency in spring at the time of PostConstruct
[英]Spring dependency @PostConstruct
假設我在 Spring @Configuration
有這個依賴項:
@Bean
public SomeClass someClass(SomeClass1 someClass1, SomeClass2 someClass2, ...) {
return new SomeClass(someClass1, someClass2, ...);
}
假設我想在@PostConstruct
中做一些包含someClass
依賴的事情:
@PostConstruct
public void init() {
someClass.doSomething();
}
這不能注入:
@PostConstruct
public void init(SomeClass someClass) {
someClass.doSomething();
}
原因:
Caused by: java.lang.IllegalStateException: Lifecycle method annotation requires a no-arg method: ...
這不能像這樣在同一個配置中自動裝配:
@Autowire
private SomeClass someClass;
@Bean
public SomeClass someClass(SomeClass1 someClass1, SomeClass2 someClass2, ...) {
return new SomeClass(someClass1, someClass2, ...);
}
因為這會導致:
Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'globalBus': Requested bean is currently in creation: Is there an unresolvable circular reference?
一個配置可以分割(所以@Bean
轉到其他配置)和@Import
-ed通過這一個,它的工作原理確定。 可能存在其他解決方案 - 例如創建一個單獨的初始化 bean 左右。
有沒有辦法在一個@Configuration
做到這一點?
編輯
根據@SotiriosDelimanolis 的要求,使用@Autowired
時出現異常的sscce :
public class ConfigPostConstructDependenciesPrb {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);
ctx.getBean(Service.class);
ctx.close();
}
public static class Service {
private final Dependency dependency;
public Service(Dependency dependency) {
this.dependency = dependency;
}
public void work() {
System.out.println(dependency.getNum());
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Service [dependency=");
sb.append(dependency);
sb.append("]");
return sb.toString();
}
}
public static class Dependency {
private final int num;
public Dependency(int num) {
this.num = num;
}
public int getNum() {
return this.num;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("SomeClass1 [num=");
sb.append(num);
sb.append("]");
return sb.toString();
}
}
@Configuration
public static class BaseConfig {
@Autowired
private Service service;
@Bean
public Dependency dependency() {
return new Dependency(42);
}
@Bean
public Service service(Dependency dependency) {
return new Service(dependency);
}
@PostConstruct
public void init() {
service.work();
}
}
@Configuration
@Import(BaseConfig.class)
public static class Config {
@Autowired
private Service service;
}
}
試試這個方法:
public class ConfigPostConstructDependenciesPrb {
public static void main(String[] args) {
try {
AnnotationConfigApplicationContext ctx =
new AnnotationConfigApplicationContext(BaseConfig.class);
ctx.registerShutdownHook();
ctx.getBean(Service.class);
ctx.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
@Configuration
class BaseConfig {
@Autowired
private Service service;
@Bean
public Dependency dependency() {
return new Dependency(42);
}
@Bean
public Service service(Dependency dependency) {
return new Service(dependency);
}
@PostConstruct
public void init() {
this.service.work();
}
}
class Dependency {
private int num;
public Dependency() {
}
public Dependency(int num) {
this.num = num;
}
public int getNum() {
return this.num;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("SomeClass1 [num=");
sb.append(num);
sb.append("]");
return sb.toString();
}
}
class Service {
private Dependency dependency;
public Service() {
}
public Service(Dependency dependency) {
this.dependency = dependency;
}
public void work() {
System.out.println(dependency.getNum());
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Service [dependency=");
sb.append(dependency);
sb.append("]");
return sb.toString();
}
}
(在 Spring 4.3.6 中測試)
在 @Configuration 中創建一個嵌套類,並在那里放置@Autowired service
和@PostConstruct init()
:
@Configuration
public static class BaseConfig {
//...
@Bean
public Service service(Dependency dependency) {
return new Service(dependency);
}
@Configuration
public static class Setup {
@Autowired
private Service service;
@PostConstruct
public void init() {
service.work();
}
}
}
以下是相應更新的完整示例。
請注意,您不必明確提及BaseConfig.Setup
(看看@Import
之前注釋Config
類-它只是指BaseConfig
本身)。
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.*;
import javax.annotation.PostConstruct;
public class ConfigPostConstructDependenciesPrb {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);
ctx.getBean(Service.class);
ctx.close();
}
public static class Service {
private final Dependency dependency;
public Service(Dependency dependency) {
this.dependency = dependency;
}
public void work() {
System.out.println(dependency.getNum());
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("Service [dependency=");
sb.append(dependency);
sb.append("]");
return sb.toString();
}
}
public static class Dependency {
private final int num;
public Dependency(int num) {
this.num = num;
}
public int getNum() {
return this.num;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("SomeClass1 [num=");
sb.append(num);
sb.append("]");
return sb.toString();
}
}
@Configuration
public static class BaseConfig {
@Bean
public Dependency dependency() {
return new Dependency(42);
}
@Bean
public Service service(Dependency dependency) {
return new Service(dependency);
}
@Configuration
public static class Setup {
@Autowired
private Service service;
@PostConstruct
public void init() {
service.work();
}
}
}
@Configuration
@Import(BaseConfig.class)
public static class Config {
@Autowired
private Service service;
}
}
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