java - Spring Boot 和 Hibernate 5 的类加载错误

Question

我最近将一个基于 Spring Boot 的应用程序从 Hibernate 4 升级到了 Hibernate 5。从那时起我发现了一个类加载问题。显然，hibernate 类和我的域类由两个不同的类加载器加载。只有当我使用 Spring DevTools 和 Hibernate 5 启动应用程序时才会发生这种情况。组合 DevTools/Hibernate 4、mvn spring-boot:run/Hibernate 5 有效。

可以使用以下简单的 spring boot 应用重现该问题(完整的 eclipse 项目可用 here)

@Entity
public class Employee implements Serializable {
    private static final long serialVersionUID = 1L;

    private Long     id;
    private String   firstName;
    private String   lastName;

    public Employee() {  
    }

    public Employee(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Id @GeneratedValue
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    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;
    }

    public String toString() {
        return id + ": " + lastName + ", " + firstName;
    }
}

public class AppConfig {

    @Autowired
    private DataSource dataSource;

    @SuppressWarnings("serial")
    @Bean
    public LocalSessionFactoryBean sessionFactory() {

        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        sessionFactory.setPackagesToScan("problem.domain");
        sessionFactory.setHibernateProperties(new Properties() {
            {
                setProperty("hibernate.dialect", "org.hibernate.dialect.DerbyTenSevenDialect");
                setProperty("hibernate.hbm2ddl.auto", "create-drop");
                setProperty("hibernate.current_session_context_class", "thread");
            }
        });

        return sessionFactory;
    }
}

@Component
public class DatabaseInitializer implements ApplicationRunner {

    @Autowired
    private SessionFactory sessionFactory;

    @Override
    public void run(ApplicationArguments args) throws Exception {

        Session session = sessionFactory.getCurrentSession();
        Transaction tx = session.beginTransaction();
        Employee empl = new Employee("John", "Doe");
        session.persist(empl);
        tx.commit();
    }
}

@SpringBootApplication
public class SpringBootMain {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SpringBootMain.class, args);
    }
}

pom.xml:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>swt6.spring</groupId>
    <artifactId>hibernate5-problem</artifactId>
    <packaging>jar</packaging>
    <version>1.0.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.2.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
        <hibernate.version>5.1.0.Final</hibernate.version>
        <derby.version>10.12.1.1</derby.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derby</artifactId>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

使用 Spring DevTools 运行此程序会导致以下错误:

2016-02-15 18:30:48.315  INFO 13828 --- [  restartedMain] o.h.t.schema.internal.SchemaCreatorImpl  : HHH000476: Executing import script 'org.hibernate.tool.schema.internal.exec.ScriptSourceInputNonExistentImpl@55ad1b60'
2016-02-15 18:30:48.509  INFO 13828 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2016-02-15 18:30:48.536  INFO 13828 --- [  restartedMain] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2016-02-15 18:30:48.582 ERROR 13828 --- [  restartedMain] o.h.p.access.spi.GetterMethodImpl        : HHH000122: IllegalArgumentException in class: problem.domain.Employee, getter method of property: id
2016-02-15 18:30:48.583 ERROR 13828 --- [  restartedMain] o.s.boot.SpringApplication               : Application startup failed

java.lang.IllegalStateException: Failed to execute ApplicationRunner
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:800) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:787) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:777) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1191) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1180) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    at problem.main.SpringBootMain.main(SpringBootMain.java:10) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_66]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_66]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_66]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_66]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-1.3.2.RELEASE.jar:1.3.2.RELEASE]
Caused by: org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of problem.domain.Employee.id
    at org.hibernate.property.access.spi.GetterMethodImpl.get(GetterMethodImpl.java:64) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:223) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4633) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4344) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:226) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:499) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:99) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:778) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:751) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:756) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_66]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_66]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_66]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_66]
    at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:338) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    at com.sun.proxy.$Proxy56.persist(Unknown Source) ~[na:na]
    at problem.main.DatabaseInitializer.run(DatabaseInitializer.java:24) ~[classes/:na]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:797) [spring-boot-1.3.2.RELEASE.jar:1.3.2.RELEASE]
    ... 11 common frames omitted
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_66]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_66]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_66]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_66]
    at org.hibernate.property.access.spi.GetterMethodImpl.get(GetterMethodImpl.java:41) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
    ... 29 common frames omitted

2016-02-15 18:30:48.585  INFO 13828 --- [  restartedMain] .b.l.ClasspathLoggingApplicationListener : Application failed to start with classpath: [file:/D:/P20058/Documents/FH/Lehre/SWT6U/Uebungen/SpringWeb/hibernate5-problem/target/classes/]
2016-02-15 18:30:48.585  INFO 13828 --- [  restartedMain] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report enable debug logging (start with --debug)


2016-02-15 18:30:48.585  INFO 13828 --- [  restartedMain] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@63e38bca: startup date [Mon Feb 15 18:30:46 CET 2016]; root of context hierarchy
2016-02-15 18:30:48.587  INFO 13828 --- [  restartedMain] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown
2016-02-15 18:30:48.587  INFO 13828 --- [  restartedMain] .SchemaDropperImpl$DelayedDropActionImpl : HHH000477: Starting delayed drop of schema as part of SessionFactory shut-down'
2016-02-15 18:30:48.604  INFO 13828 --- [  restartedMain] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2016-02-15 18:30:48.604  INFO 13828 --- [  restartedMain] .SchemaDropperImpl$DelayedDropActionImpl : HHH000477: Starting delayed drop of schema as part of SessionFactory shut-down'

Answer 1

使用 Spring Boot 支持 Hibernate 5 有一个 Unresolved 问题 here .

在您的示例中，有两个类加载器:

1. 系统类加载器
2. Spring Boot DevTools 类加载器，支持重启功能

Hibernate ClassLoaderService 的默认实现首先在他自己的类加载器中查找类，然后在 spring 类加载器中查找类。

你的类是spring加载的(有restart classloader)，通过persistent-unit给hibernate，但是hibernate用他的ClassLoaderService重新加载这个类，在他自己的classloader(系统cl)中找到。加载了两个类，结果就是您看到的错误。

Spring 可以配置为在重启类加载器中加载 hibernate，但我没有成功隔离一组库:仅添加 hibernate-* 失败，并出现来自 spring-orm 的错误或代理构建器中不可见的 EntityManager。

一个有效的解决方法(但真的很难看!):添加 META-INF/spring-devtools.properties

restart.include.all=.*

我想有比这个更好的解决方案