java - 使用 Spring Boot 注册普通 java 类

Question

我正在尝试在 Spring 应用程序上下文中注册一个普通的 java 类。我可以@Autowire

在其他类中使用。

普通 Java 类:

public class MyBean {
    public void showMe() {
        System.out.println("test me");
    }
}

在 Spring 上下文中注册类的代码

public class CustomeBeanCongif implements ApplicationListener<ApplicationEvent> {

    @Autowired
    GenericApplicationContext ctx;

    @Override
    public void onApplicationEvent(ApplicationEvent event) {

        System.out.println("Starting Config");
        BeanDefinition beanDef = new GenericBeanDefinition();
        beanDef.setScope(BeanDefinition.SCOPE_SINGLETON);
        beanDef.setAutowireCandidate(true);
        try {
            ctx.registerBean("myxyzBean", MyBeanStandalone.class, new MyBeanStandalone(), beanDef);
        }
        catch(BeanDefinitionOverrideException e) {
            System.out.println("CLassName: " + e.getBeanDefinition().getBeanClassName());
            System.out.println(e.getBeanName());
            System.out.println(e.getBeanDefinition());
            e.printStackTrace();
        }
    }

}

驱动程序类别

@SpringBootApplication
public class DemoApplication implements CommandLineRunner {

    @Autowired
    ApplicationContext ctx;

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);

    }

    @Override
    public void run(String... args) throws Exception {
        MyBean test = ctx.getBean(MyBean.class);
    }

}

应用程序抛出错误，指出另一个 bean 已注册。日志:

2020-03-09 12:10:47.634  INFO 26684 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
Starting Config
2020-03-09 12:10:48.740  INFO 26684 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 2.272 seconds (JVM running for 2.812)
Starting Config
CLassName: com.example.demo.config.MyBean
myxyzBean
Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null
org.springframework.beans.factory.support.BeanDefinitionOverrideException: Invalid bean definition with name 'myxyzBean' defined in null: Cannot register bean definition [Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] for bean 'myxyzBean': There is already [Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] bound.
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.registerBeanDefinition(DefaultListableBeanFactory.java:927)
    at org.springframework.context.support.GenericApplicationContext.registerBeanDefinition(GenericApplicationContext.java:323)
    at org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerBeanDefinition(BeanDefinitionReaderUtils.java:167)
    at org.springframework.context.annotation.AnnotatedBeanDefinitionReader.doRegisterBean(AnnotatedBeanDefinitionReader.java:285)
    at org.springframework.context.annotation.AnnotatedBeanDefinitionReader.registerBean(AnnotatedBeanDefinitionReader.java:233)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.registerBean(AnnotationConfigApplicationContext.java:188)
    at org.springframework.context.support.GenericApplicationContext.registerBean(GenericApplicationContext.java:387)
    at com.example.demo.config.CustomeBeanCongif.onApplicationEvent(CustomeBeanCongif.java:33)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360)
    at org.springframework.boot.context.event.EventPublishingRunListener.started(EventPublishingRunListener.java:98)
    at org.springframework.boot.SpringApplicationRunListeners.started(SpringApplicationRunListeners.java:71)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at com.example.demo.DemoApplication.main(DemoApplication.java:22)
2020-03-09 12:10:48.751  INFO 26684 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
Starting Config
CLassName: com.example.demo.config.MyBean
myxyzBean
Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null
org.springframework.beans.factory.support.BeanDefinitionOverrideException: Invalid bean definition with name 'myxyzBean' defined in null: Cannot register bean definition [Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] for bean 'myxyzBean': There is already [Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] bound.
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.registerBeanDefinition(DefaultListableBeanFactory.java:927)
    at org.springframework.context.support.GenericApplicationContext.registerBeanDefinition(GenericApplicationContext.java:323)
    at org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerBeanDefinition(BeanDefinitionReaderUtils.java:167)
    at org.springframework.context.annotation.AnnotatedBeanDefinitionReader.doRegisterBean(AnnotatedBeanDefinitionReader.java:285)
    at org.springframework.context.annotation.AnnotatedBeanDefinitionReader.registerBean(AnnotatedBeanDefinitionReader.java:233)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.registerBean(AnnotationConfigApplicationContext.java:188)
    at org.springframework.context.support.GenericApplicationContext.registerBean(GenericApplicationContext.java:387)
    at com.example.demo.config.CustomeBeanCongif.onApplicationEvent(CustomeBeanCongif.java:33)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360)
    at org.springframework.boot.context.event.EventPublishingRunListener.failed(EventPublishingRunListener.java:112)
    at org.springframework.boot.SpringApplicationRunListeners.callFailedListener(SpringApplicationRunListeners.java:90)
    at org.springframework.boot.SpringApplicationRunListeners.failed(SpringApplicationRunListeners.java:83)
    at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:797)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:325)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at com.example.demo.DemoApplication.main(DemoApplication.java:22)
2020-03-09 12:10:48.762 ERROR 26684 --- [           main] o.s.boot.SpringApplication               : Application run failed

java.lang.IllegalStateException: Failed to execute CommandLineRunner
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:787) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:768) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:322) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at com.example.demo.DemoApplication.main(DemoApplication.java:22) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myxyzBean': Cannot create inner bean '(inner bean)#662706a7' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#662706a7': Instantiation of bean failed; nested exception is java.lang.IllegalStateException: No bean class specified on bean definition
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:389) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:134) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:705) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:196) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1358) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1204) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:227) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveNamedBean(DefaultListableBeanFactory.java:1155) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveBean(DefaultListableBeanFactory.java:416) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:349) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:342) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1126) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at com.example.demo.DemoApplication.run(DemoApplication.java:47) [classes/:na]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:784) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    ... 5 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#662706a7': Instantiation of bean failed; nested exception is java.lang.IllegalStateException: No bean class specified on bean definition
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1320) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1214) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:374) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    ... 23 common frames omitted
Caused by: java.lang.IllegalStateException: No bean class specified on bean definition
    at org.springframework.beans.factory.support.AbstractBeanDefinition.getBeanClass(AbstractBeanDefinition.java:423) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:68) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1312) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    ... 27 common frames omitted

Starting Config
CLassName: com.example.demo.config.MyBean
myxyzBean
Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null
org.springframework.beans.factory.support.BeanDefinitionOverrideException: Invalid bean definition with name 'myxyzBean' defined in null: Cannot register bean definition [Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] for bean 'myxyzBean': There is already [Generic bean: class [com.example.demo.config.MyBean]; scope=singleton; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] bound.
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.registerBeanDefinition(DefaultListableBeanFactory.java:927)
    at org.springframework.context.support.GenericApplicationContext.registerBeanDefinition(GenericApplicationContext.java:323)
    at org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerBeanDefinition(BeanDefinitionReaderUtils.java:167)
    at org.springframework.context.annotation.AnnotatedBeanDefinitionReader.doRegisterBean(AnnotatedBeanDefinitionReader.java:285)
    at org.springframework.context.annotation.AnnotatedBeanDefinitionReader.registerBean(AnnotatedBeanDefinitionReader.java:233)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.registerBean(AnnotationConfigApplicationContext.java:188)
    at org.springframework.context.support.GenericApplicationContext.registerBean(GenericApplicationContext.java:387)
    at com.example.demo.config.CustomeBeanCongif.onApplicationEvent(CustomeBeanCongif.java:33)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360)
    at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1012)
    at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:978)
    at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:803)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:325)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at com.example.demo.DemoApplication.main(DemoApplication.java:22)

MyBean 类是由第三方 jar 提供的，因此我无法对其进行更改。感谢您的帮助。

Answer 1

删除您的CustomeBeanCongif，然后将@Bean方法添加到您的@SpringBootApplication或自定义@Configuration类。

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        ApplicationContext ctx = SpringApplication.run(DemoApplication.class, args);
        MyBean test = ctx.getBean(MyBean.class);
    }

   @Bean
   public MyBean myBean() {
     return new MyBean();
   }
}

这就是注册 bean 所需要的。