java未能在Bean:NullPointerException中实例化LoggerFactory
我是Spring框架的新手，在尝试使用slf4j创建LoggerFactory时遇到了困难。我做了很多故障排除，怀疑我的pom可能有问题。xml文件依赖性，尽管我不确定。最终，我使用slf4j的目标是@Autowire一个记录器，它来自于调用它的类。我真的很感激任何帮助
伐木豆
import org.slf4j.*;
import org.springframework.beans.factory.InjectionPoint;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;
import static java.util.Optional.*;
import org.springframework.core.MethodParameter;
import java.lang.reflect.Field;
/**
* @author me
*
*/
@Configuration
public class LoggingConfiguration {
/**
* @param ip
* @return sd
*/
@Bean
@Scope("prototype")
public Logger logger(final InjectionPoint ip) {
// NULL POINTER EXCEPTION ERROR in next line
return LoggerFactory.getLogger(of(ip.getMethodParameter())
.<Class>map(MethodParameter::getContainingClass)
.orElseGet( () ->
ofNullable(ip.getField())
.map(Field::getDeclaringClass)
.orElseThrow (IllegalArgumentException::new)
)
);
}
}
波姆。xml
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<mainClass>my.project.example</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
<goal>build-info</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<!-- logging interface -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-1.2-api</artifactId>
<version>2.11.2</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.11.2</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.0.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
</project>
错误片段
Caused by: java.lang.NullPointerException
at java.util.Objects.requireNonNull(Objects.java:221) ~[?:?]
at java.util.Optional.<init>(Optional.java:107) ~[?:?]
at java.util.Optional.of(Optional.java:120) ~[?:?]
at
com.my.example.LoggingConfiguration.logger(LoggingConfiguration.java:24) ~[classes/:?]
at com.my.example.LoggingConfiguration$$EnhancerBySpringCGLIB$$25ba5d70.CGLIB$logger$0(<generated>) ~[classes/:?]
at com.my.example.LoggingConfiguration$$EnhancerBySpringCGLIB$$25ba5d70$$FastClassBySpringCGLIB$$cad7c364.invoke(<generated>) ~[classes/:?]
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.3.7.jar:5.3.7]
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:331) ~[spring-context-5.3.7.jar:5.3.7]
at com.my.example.LoggingConfiguration$$EnhancerBySpringCGLIB$$25ba5d70.logger(<generated>) ~[classes/:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:638) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1334) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:564) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:353) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:657) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1413) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:601) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:524) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.7.jar:5.3.7]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:657) ~[spring-beans-5.3.7.jar:5.3.7]
共 (0) 个答案