Spring Boot 中令人困惑的 NullPointer 异常答案

【问题标题】：Confusing NullPointer Exception in Spring BootSpring Boot 中令人困惑的 NullPointer 异常
【发布时间】：2019-04-01 12:17:56
【问题描述】：

我想知道是否有人可以帮助我调查 Spring 的奇怪（至少对我而言）行为。我实际上正在对我的项目进行更改。启动我的代码后，我得到了一个很好的旧 NullPointer 异常。但问题是 Spring 没有指定此错误发生的位置。我只得到了一些关于org.hibernate.tuple.entity.PojoEntityTuplizer 和javaassist.proxy.ProxyFactory.CreateClass 的奇怪信息。

这里显示的代码有点复杂，所以我会为您提供我的 GitHub 存储库链接：https://github.com/sajmon2325/Spring-Pet-Clinic.git

我已经初始化了我所有的集合，例如：

Set<Owner> owners  = new HashSet<>();

所以不应该有任何未初始化的集合。

我还在我的类中包含了验证，所以我必须处理所有 NullPointer 异常。

所有者实体

package guru.springframework.sfgpetclinic.model;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name = "owners")
public class Owner extends Person {

    @Column(name = "address")
    private String address;
    @Column(name = "city")
    private String city;
    @Column(name = "telephone")
    private String telephone;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "owner")
    private Set<Pet> pets = new HashSet<>();

    Some getters and setters

}

人物实体

package guru.springframework.sfgpetclinic.model;

import javax.persistence.Column;
import javax.persistence.MappedSuperclass;

@MappedSuperclass
public class Person extends BaseEntity {

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

所有者存储库

package guru.springframework.sfgpetclinic.repositories;

import guru.springframework.sfgpetclinic.model.Owner;
import org.springframework.data.repository.CrudRepository;

public interface OwnerRepository extends CrudRepository<Owner, 
Long> {

    Owner findByLastName(String lastName);
}

业主服务

package guru.springframework.sfgpetclinic.services;

import guru.springframework.sfgpetclinic.model.Owner;


public interface OwnerService extends CrudService<Owner, Long> {

    Owner findByLastName(String lastName);

}

...

@Service
@Profile("springdatajpa")
public class OwnerSDJpaService implements OwnerService {

    private final OwnerRepository ownerRepository;
    private final PetRepository petRepository;
    private final PetTypeRepository petTypeRepository;


    public OwnerSDJpaService(OwnerRepository ownerRepository, 
         PetRepository petRepository, PetTypeRepository 
          petTypeRepository) {
            this.ownerRepository = ownerRepository;
            this.petRepository = petRepository;
            this.petTypeRepository = petTypeRepository;
    }       


    @Override
    public Owner findByLastName(String lastName) {
            return ownerRepository.findByLastName(lastName);
    }

    @Override
    public Set<Owner> findAll() {
        Set<Owner> owners = new HashSet<>();
        ownerRepository.findAll().forEach(owners::add);

        return owners;
    }

    @Override
    public Owner findById(Long aLong) {
        return ownerRepository.findById(aLong).orElse(null);
    }

    @Override
    public Owner save(Owner object) {
        return ownerRepository.save(object);
    }

    @Override
    public void delete(Owner object) {
        ownerRepository.delete(object);
    }

    @Override
    public void deleteById(Long aLong) {
        ownerRepository.deleteById(aLong);
    }
}

这是完整的堆栈跟踪，但很长

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-04-02 22:27:38.143 ERROR 13892 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1708) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:581) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:503) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1089) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:859) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at guru.springframework.sfgpetclinic.SfgPetClinicApplication.main(SfgPetClinicApplication.java:10) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-2.0.3.RELEASE.jar:2.0.3.RELEASE]
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:402) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1767) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1704) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    ... 21 common frames omitted
Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:123) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:77) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.metamodel.internal.MetamodelImpl.initialize(MetamodelImpl.java:129) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:300) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:462) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:892) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:390) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    ... 25 common frames omitted
Caused by: org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:91) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:116) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:382) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:519) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:124) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:96) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 33 common frames omitted
Caused by: java.lang.reflect.InvocationTargetException: null
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:88) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 42 common frames omitted
Caused by: java.lang.NullPointerException: null
    at javassist.util.proxy.SecurityActions.setAccessible(SecurityActions.java:103) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass3(DefineClassHelper.java:151) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass2(DefineClassHelper.java:134) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass(DefineClassHelper.java:95) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.FactoryHelper.toClass(FactoryHelper.java:131) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass3(ProxyFactory.java:530) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass2(ProxyFactory.java:515) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass1(ProxyFactory.java:451) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass(ProxyFactory.java:422) ~[javassist-3.22.0-GA.jar:na]
    at org.hibernate.proxy.pojo.javassist.JavassistProxyFactory.postInstantiate(JavassistProxyFactory.java:75) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:162) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:156) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:58) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 47 common frames omitted


Process finished with exit code 0Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-04-02 22:27:38.143 ERROR 13892 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1708) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:581) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:503) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1089) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:859) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at guru.springframework.sfgpetclinic.SfgPetClinicApplication.main(SfgPetClinicApplication.java:10) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-2.0.3.RELEASE.jar:2.0.3.RELEASE]
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:402) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1767) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1704) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    ... 21 common frames omitted
Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:123) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:77) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.metamodel.internal.MetamodelImpl.initialize(MetamodelImpl.java:129) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:300) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:462) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:892) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:390) ~[spring-orm-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    ... 25 common frames omitted
Caused by: org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:91) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:116) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:382) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:519) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:124) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:96) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 33 common frames omitted
Caused by: java.lang.reflect.InvocationTargetException: null
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
    at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:88) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 42 common frames omitted
Caused by: java.lang.NullPointerException: null
    at javassist.util.proxy.SecurityActions.setAccessible(SecurityActions.java:103) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass3(DefineClassHelper.java:151) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass2(DefineClassHelper.java:134) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass(DefineClassHelper.java:95) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.FactoryHelper.toClass(FactoryHelper.java:131) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass3(ProxyFactory.java:530) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass2(ProxyFactory.java:515) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass1(ProxyFactory.java:451) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.ProxyFactory.createClass(ProxyFactory.java:422) ~[javassist-3.22.0-GA.jar:na]
    at org.hibernate.proxy.pojo.javassist.JavassistProxyFactory.postInstantiate(JavassistProxyFactory.java:75) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:162) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:156) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:58) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    ... 47 common frames omitted


Process finished with exit code 0

【问题讨论】：

Spring 有相当广泛和有用的错误消息。请将整个错误消息（包括堆栈跟踪）添加到您的问题中。

标签： spring-boot nullpointerexception

【解决方案1】：

您很可能在 JDK 11 或更高版本上运行。您使用的库之一是 javassist（可能作为 Spring 框架的依赖项）。版本 3.22 与 JDK 11 不兼容并导致错误。

要么升级到 javassist 3.24（通过升级到最新的 Spring Boot 版本 2.2.4.RELEASE，它有依赖关系）要么降级到 JDK 8。

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.3.RELEASE</version>
    </parent>

作为调查 Java 错误日志的提示：

找到第一个错误。你的情况是：2019-04-02 22:27:38.143 ERROR 13892 --- [ restartedMain] o.s.boot.SpringApplication : Application run failed
按照相关的堆栈跟踪并转到 innermost 异常，即在下一个错误开始之前转到最后一个 Caused by:。你的情况是：

Caused by: java.lang.NullPointerException: null
    at javassist.util.proxy.SecurityActions.setAccessible(SecurityActions.java:103) ~[javassist-3.22.0-GA.jar:na]
    at javassist.util.proxy.DefineClassHelper.toClass3(DefineClassHelper.java:151) ~[javassist-3.22.0-GA.jar:na]

这是您要调查的真正原因。

【讨论】：

【解决方案2】：

谢谢科多 :) 在您发表评论前几分钟，我已经找到了答案。对我来说这是一个棘手的问题。我假设空指针异常是由缺少 getter/setter 或缺少构造函数引起的。但是当我分析错误时，我找到了这一行：

"Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister"

并且做了一个研究，发现我需要添加：

<dependency>
    <groupId>org.javassist</groupId>
    <artifactId>javassist</artifactId>
    <version>3.23.1-GA</version>
</dependency>

这个依赖到我的 pom.xml 文件中。而这个问题正是你上面描述的。

感谢您的帮助和快速响应:) 这一天我学到了一些新东西

【讨论】：

谢谢西蒙。解决方案添加此依赖项后对我来说完美。
您可以升级到最新的 Spring Boot 版本 2.2.4.RELEASE，它具有依赖关系（由 hibernate-core 传递）到更新的 javassist 版本 3.24.0-GA。