我需要动态创建一个Spring托管类，该类依赖于所传递的属性，然后才能设置其实例化属性之一。
理想情况下，我想在构造函数中传递所需的属性，但是在实例化bean时，Spring似乎不允许使用非默认构造函数。
SubBean.java：
@Configuration
public class SubBean extends SuperBean {
@Autowired
private LdapTemplate ldapTemplate;
public SubBean() {
super();
}
@Bean
public LdapTemplate setLdapTemplate() {
LdapContextSource contextSource= new LdapContextSource();
int separatorLocation = this.string.indexOf('/', 8);
contextSource.setUrl(this.string.substring(0, separatorLocation));
contextSource.setBase(this.string.substring(separatorLocation + 1));
contextSource.setAnonymousReadOnly(true);
return new LdapTemplate(contextSource);
}
public List<Computer> searchDirectory() {
SearchControls searchControls = new SearchControls();
searchControls.setCountLimit(25);
searchControls.setSearchScope(SearchControls.SUBTREE_SCOPE);
List<Computer> computers = (List<Computer>) ldapTemplate.search(
LdapQueryBuilder.query().filter("OU=Domain Controllers"), new ComputerAttributesMapper());
return computers;
}
private class ComputerAttributesMapper implements AttributesMapper<Computer> {
@Override
public Computer mapFromAttributes(Attributes attributes) throws NamingException {
Computer computer = new Computer();
computer.setName((String) attributes.get("name").get(0));
return computer;
}
}
@Override
public void doStuff() {
List<Computer> computers = searchDirectory();
System.out.println(computers);
}
}
SpringBootConfiguration.java：SubBean有多种类型，因此需要将它们作为超类引用。
@SpringBootApplication
public class SpringBootConfiguration {
@Autowired
private ConfigFile configFile;
@Autowired
private AutowireCapableBeanFactory beanFactory;
public static void main(String[] args) {
SpringApplication.run(SpringBootConfiguration.class, args);
}
@Bean
//Load configuration from a JSON file
public ConfigFile configFile() throws JsonMappingException, IOException {
ObjectMapper mapper = new ObjectMapper();
File file = new File("configuration.json");
ConfigFile cf = mapper.readValue(file, ConfigFile.class);
cf.setFile(file);
return cf;
}
@Bean
public CommandLineRunner run(RestTemplate restTemplate, ApplicationContext ctx) throws Exception {
return args -> {
System.out.println(configFile);
List<Poller> configuredPollers = configFile.getConfiguration().getPollers();
for (Poller p : configuredPollers) {
//The class name is specified in the JSON configuration file.
Class<SuperBean> clazz = (Class<SuperBean>) Class.forName(p.getType());
//Use Spring to set up the object - this will try to autowire the ldapTemplate property and fail
SuperBean superBean = (SuperBean) beanFactory.createBean(clazz, AutowireCapableBeanFactory.AUTOWIRE_BY_NAME, true);
//Because the beanFactory only uses the default constructor, I have to explicitly set its properties
superBean.setString(p.getString());
superBean.doStuff();
}
};
}
}
运行时，出现异常：
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'subBean': Unsatisfied dependency expressed through field 'ldapTemplate'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'setLdapTemplate' defined in class path resource [test/SubBean.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.ldap.core.LdapTemplate]: Circular reference involving containing bean 'subBean' - consider declaring the factory method as static for independence from its containing instance. Factory method 'setLdapTemplate' threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:882)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
at test.SpringBootConfiguration.main(SpringBootConfiguration.java:28)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'setLdapTemplate' defined in class path resource [test/SubBean.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.ldap.core.LdapTemplate]: Circular reference involving containing bean 'subBean' - consider declaring the factory method as static for independence from its containing instance. Factory method 'setLdapTemplate' threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:656)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:484)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1290)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1210)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640)
... 19 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.ldap.core.LdapTemplate]: Circular reference involving containing bean 'subBean' - consider declaring the factory method as static for independence from its containing instance. Factory method 'setLdapTemplate' threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:651)
... 32 more
Caused by: java.lang.NullPointerException
at test.SubBean.setLdapTemplate(SubBean.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
... 33 more
这是因为this.string中的int separatorLocation = this.string.indexOf('/', 8);未设置为SubBean.java。在手动设置对象属性之后，我将需要能够在构造函数中设置string（Spring在托管bean中不允许）或自动装配ldapTemplate。
我需要动态创建一个Spring托管类，该类依赖于传递的属性，然后才能设置其实例化属性之一。理想情况下，我想通过...
请勿在@Bean类中使用@Service。 @Bean方法属于@Configuration类。