Java 具有AnnotationConfigApplicationContext的Spring应用程序：获取运行时异常

这是我的一个问题-->

我扩展了相同的示例，我希望工作“很好”，但是我得到了NullPointerException

以下是完整的源代码：

FirstBean.java

package com.example;

import org.springframework.stereotype.Component;

@Component
public class FirstBean {

    public FirstBean() {

    }

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "FirstBean [name=" + name + "]";
    }
}

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

@Component
@Configuration
@ComponentScan(basePackages = { "com.example" })
public class SomeBean {

    @Autowired
    private FirstBean fb;

    @Bean
    FirstBean instantiateFirstBean() {
        return new FirstBean();
    }

    public SomeBean() {
        // this.fb.setName("Some Name"); -> this was causing problem as 
        // bean isn't still created fully
    }

    public void print() {
        this.fb.toString(); 
    }

    @PostConstruct
    void post() {
        fb.setName("Some name");
    }
}

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;

@Configuration
@ComponentScan(basePackages = { "com.example" })
@PropertySource(ignoreResourceNotFound = true, value = "classpath:/application.props")
public class MainDriver {

    @Autowired
    private Environment env;

    @Autowired
    private ConfigurableEnvironment cenv;

    @Autowired
    ApplicationContext ctx;

    @Autowired
    private SomeBean sb;

    @Bean
    public SomeBean instantiateSomeBean() {
        return new SomeBean();
    }

    public static void main(String[] args) {

        ApplicationContext ctx = new AnnotationConfigApplicationContext(MainDriver.class);

        MainDriver l = ctx.getBean(MainDriver.class);
        System.out.println("In main() the ctx is " + ctx);
        l.test();
    }

    public void test() {
        System.out.println("hello");
        sb.print();
    }
}

SomeBean.java

package com.example;

import org.springframework.stereotype.Component;

@Component
public class FirstBean {

    public FirstBean() {

    }

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "FirstBean [name=" + name + "]";
    }
}

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

@Component
@Configuration
@ComponentScan(basePackages = { "com.example" })
public class SomeBean {

    @Autowired
    private FirstBean fb;

    @Bean
    FirstBean instantiateFirstBean() {
        return new FirstBean();
    }

    public SomeBean() {
        // this.fb.setName("Some Name"); -> this was causing problem as 
        // bean isn't still created fully
    }

    public void print() {
        this.fb.toString(); 
    }

    @PostConstruct
    void post() {
        fb.setName("Some name");
    }
}

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;

@Configuration
@ComponentScan(basePackages = { "com.example" })
@PropertySource(ignoreResourceNotFound = true, value = "classpath:/application.props")
public class MainDriver {

    @Autowired
    private Environment env;

    @Autowired
    private ConfigurableEnvironment cenv;

    @Autowired
    ApplicationContext ctx;

    @Autowired
    private SomeBean sb;

    @Bean
    public SomeBean instantiateSomeBean() {
        return new SomeBean();
    }

    public static void main(String[] args) {

        ApplicationContext ctx = new AnnotationConfigApplicationContext(MainDriver.class);

        MainDriver l = ctx.getBean(MainDriver.class);
        System.out.println("In main() the ctx is " + ctx);
        l.test();
    }

    public void test() {
        System.out.println("hello");
        sb.print();
    }
}

MainDriver.java

package com.example;

import org.springframework.stereotype.Component;

@Component
public class FirstBean {

    public FirstBean() {

    }

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "FirstBean [name=" + name + "]";
    }
}

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

@Component
@Configuration
@ComponentScan(basePackages = { "com.example" })
public class SomeBean {

    @Autowired
    private FirstBean fb;

    @Bean
    FirstBean instantiateFirstBean() {
        return new FirstBean();
    }

    public SomeBean() {
        // this.fb.setName("Some Name"); -> this was causing problem as 
        // bean isn't still created fully
    }

    public void print() {
        this.fb.toString(); 
    }

    @PostConstruct
    void post() {
        fb.setName("Some name");
    }
}

package com.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;

@Configuration
@ComponentScan(basePackages = { "com.example" })
@PropertySource(ignoreResourceNotFound = true, value = "classpath:/application.props")
public class MainDriver {

    @Autowired
    private Environment env;

    @Autowired
    private ConfigurableEnvironment cenv;

    @Autowired
    ApplicationContext ctx;

    @Autowired
    private SomeBean sb;

    @Bean
    public SomeBean instantiateSomeBean() {
        return new SomeBean();
    }

    public static void main(String[] args) {

        ApplicationContext ctx = new AnnotationConfigApplicationContext(MainDriver.class);

        MainDriver l = ctx.getBean(MainDriver.class);
        System.out.println("In main() the ctx is " + ctx);
        l.test();
    }

    public void test() {
        System.out.println("hello");
        sb.print();
    }
}

我希望

SomeBean

能够自动连接到

上（
ctx
，
env
，
cenv
都能自动连接到一起），但它没有连接到，我遇到了运行时异常

Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'mainDriver': Unsatisfied dependency expressed through field 'sb'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'someBean' defined in file [/Users/vkoul/understand-code/platform/stream-base/trunk/target/classes/com/example/SomeBean.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]: Constructor threw exception; nested exception is java.lang.NullPointerException
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'mainDriver': Unsatisfied dependency expressed through field 'sb'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'someBean' defined in file [/Users/vkoul/understand-code/platform/stream-base/trunk/target/classes/com/example/SomeBean.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:370)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1336)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:572)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:548)
    at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init>(AnnotationConfigApplicationContext.java:88)
    at com.example.MainDriver.main(MainDriver.java:37)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'someBean' defined in file [/Users/vkoul/understand-code/platform/stream-base/trunk/target/classes/com/example/SomeBean.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1228)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1127)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:251)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1135)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:581)
    ... 14 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:182)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1220)
    ... 25 more
Caused by: java.lang.NullPointerException
    at com.example.SomeBean.<init>(SomeBean.java:23)
    at com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b.<init>(<generated>)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:170)
    ... 27 more


上下文初始化期间遇到异常-取消刷新尝试：org.springframework.beans.factory.unsatifiedpendencyException:创建名为“mainDriver”的bean时出错：通过字段“sb”表示的未满足的依赖关系；嵌套异常为org.springframework.beans.factory.beancreatitionException:创建名为“someBean”的bean时出错，该bean在文件[/Users/vkoul/understand code/platform/stream base/trunk/target/classes/com/example/someBean.class]中定义：bean实例化失败；嵌套异常为org.springframework.beans.BeanInstantiationException:未能实例化[com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]：构造函数引发异常；嵌套异常是java.lang.NullPointerException
线程“main”org.springframework.beans.factory.unsatifiedpendencyException中出现异常：创建名为“mainDriver”的bean时出错：通过字段“sb”表示未满足的依赖关系；嵌套异常为org.springframework.beans.factory.beancreatitionException:创建名为“someBean”的bean时出错，该bean在文件[/Users/vkoul/understand code/platform/stream base/trunk/target/classes/com/example/someBean.class]中定义：bean实例化失败；嵌套异常为org.springframework.beans.BeanInstantiationException:未能实例化[com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]：构造函数引发异常；嵌套异常是java.lang.NullPointerException
位于org.springframework.beans.factory.annotation.AutoWiredNotationBeanPostProcessor$AutoWiredFeldElement.inject（AutoWiredNotationBeanPostProcessor.java:584）
位于org.springframework.beans.factory.annotation.InjectionMetadata.inject（InjectionMetadata.java:90）
位于org.springframework.beans.factory.annotation.AutoWiredNotationBeanPostProcessor.postProcessPropertyValues（AutoWiredNotationBeanPostProcessor.java:370）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean（AbstractAutowireCapableBeanFactory.java:1336）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:572）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:495）
位于org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0（AbstractBeanFactory.java:317）
位于org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:222）
位于org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:315）
位于org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:199）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.PreInstanceSingleton（DefaultListableBeanFactory.java:759）
位于org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization（AbstractApplicationContext.java:867）
位于org.springframework.context.support.AbstractApplicationContext.refresh（AbstractApplicationContext.java:548）
位于org.springframework.context.annotation.AnnotationConfigApplicationContext。（AnnotationConfigApplicationContext.java:88）
位于com.example.MainDriver.main（MainDriver.java:37）
原因：org.springframework.beans.factory.BeanCreationException:创建名为“someBean”的bean时出错，该名称在文件[/Users/vkoul/understand code/platform/stream base/trunk/target/classes/com/example/someBean.class]中定义：bean实例化失败；嵌套异常为org.springframework.beans.BeanInstantiationException:未能实例化[com.example.SomeBean$$EnhancerBySpringCGLIB$$fad3571b]：构造函数引发异常；嵌套异常是java.lang.NullPointerException
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.InstanceBean（AbstractAutowireCapableBeanFactory.java:1228）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance（AbstractAutowireCapableBeanFactory.java:1127）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:535）
位于org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:495）
位于org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0（AbstractBeanFactory.java:317）
位于org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:222）
位于org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:315）
位于org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:199）
位于org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate（DependencyDescriptor.java:251）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency（DefaultListableBeanFactory.java:1135）
位于org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency（DefaultListableBeanFactory.java:1062）
位于org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutoWiredFeldElement.in