java - Spring Boot:“创建名称为 baseConfig 的 bean 时出错:调用 init 方法失败”NPE
问题描述
我看到运行我的应用程序时抛出了 NullPointerException。更具体地说,我的一个配置类导致 NullPointerException,我不确定为什么会发生这种情况。
我只是试图在控制器中自动装配配置类,以便我可以查看属性值是否正确填充:
@RestController
public class ApplicationController {
@Autowired
private TopicConsumerConfig topicConsumerConfig;
@RequestMapping("/")
public String showConfigs() {
return topicConsumerConfig.toString();
}
}
以下是有问题的课程:
@Component
@ConfigurationProperties
public class BaseConfig {
Properties props;
private String username;
private String hostname;
public Properties getProps() {
return props;
}
public void setProps(Properties props) {
this.props = props;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getHostname() {
return hostname;
}
public void setHostname(String hostname) {
this.hostname = hostname;
}
@PostConstruct
public void loadProperties() {
props = new Properties();
props.setProperty("hostname", this.hostname);
props.setProperty("username", this.username);
}
}
@Component
@ConfigurationProperties
public class ConsumerConfig extends BaseConfig {
private String password;
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "ConsumerConfig [hostname=" + getHostname() + ", username=" + getUsername() + ", password=" + password + "]";
}
@Override
@PostConstruct
public void loadProperties() {
super.loadProperties();
props.setProperty("password", this.password);
}
}
@Configuration
@PropertySource(
value = "classpath:consumer.properties",
ignoreResourceNotFound=false
)
@ConfigurationProperties(prefix="com.training.consumer")
public class TopicConsumerConfig extends ConsumerConfig {
}
消费者属性:
com.training.consumer.hostname=myhost
com.training.consumer.username=myusername
com.training.consumer.password=mypassword
我得到的错误如下:
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-12-16 22:10:50.428 ERROR 2010 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'baseConfig': Invocation of init method failed; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:139) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:419) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1737) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:576) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:846) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:863) ~[spring-context-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546) ~[spring-context-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
at com.example.demo.VismarkApplication.main(VismarkApplication.java:10) [classes/:na]
Caused by: java.lang.NullPointerException: null
at java.util.Hashtable.put(Hashtable.java:460) ~[na:1.8.0_181]
at java.util.Properties.setProperty(Properties.java:166) ~[na:1.8.0_181]
at com.example.demo.config.BaseConfig.loadProperties(BaseConfig.java:41) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:363) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:307) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:136) ~[spring-beans-5.1.2.RELEASE.jar:5.1.2.RELEASE]
... 18 common frames omitted
我哪里做错了?
解决方案
因为你在你的 consumer.properties 中有关注
com.training.consumer.hostname=myhost
com.training.consumer.username=myusername
com.training.consumer.password=mypassword
但是你BaseConfig
只有变量username
,password
属性没有正确映射。将您的 @ConfigurationProperties 更改为具有如下前缀属性。
@ConfigurationProperties(prefix="com.training.consumer")
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