Java Hibernate - 无法连接到 H2
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【中文标题】Java Hibernate - 无法连接到 H2【英文标题】：Java Hibernate - unable to connect to H2 【发布时间】：2019-07-26 04:34:48 【问题描述】：我需要帮助。我不知道这个项目有什么问题。我无法连接到 h2 数据库。即使我没有保留任何对象，只是关闭连接，我也会收到错误消息。
抱歉，我知道，这个问题已经被问过好几次了，但没有一个答案适合我的情况。
我得到的错误：
2019 年 3 月 4 日晚上 11:00:24 org.hibernate.Version logVersion INFO： HHH000412：休眠核心 5.2.12.Final 2019 年 3 月 4 日晚上 11:00:24 org.hibernate.cfg.Environment 信息：HHH000206： hibernate.properties 未找到 2019 年 3 月 4 日晚上 11:00:24 org.hibernate.boot.jaxb.internal.stax.LocalXmlResourceResolver resolveEntity WARN: HHH90000012: 识别过时休眠 命名空间http://hibernate.sourceforge.net/hibernate-configuration。 使用命名空间http://www.hibernate.org/dtd/hibernate-configuration 反而。对过时的 DTD/XSD 命名空间的支持可能会在 随时。 2019 年 3 月 4 日晚上 11:00:24 org.hibernate.annotations.common.reflection.java.JavaReflectionManager 信息：HCANN000001：Hibernate Commons 注释 5.0.1.Final 2019 年 3 月 4 日晚上 11:00:25 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl 配置 WARN: HHH10001002: Using Hibernate built-in connection pool （不用于生产！） org.hibernate.service.spi.ServiceException： 无法创建请求的服务 [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:271) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:233) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210) 在 org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51) 在 org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:242) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210) 在 org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352) 在 org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111) 在 org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83) 在 org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418) 在 org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87) 在 org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691) 在 org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726) 在 orm.hibernate.employees.HibernateUtils.(HibernateUtils.java:13) 在 orm.hibernate.employees.EmployeeRepository.addNewEmployee(EmployeeRepository.java:16) 在 orm.hibernate.employees.EmployeesApp.main(EmployeesApp.java:21) 造成的： org.hibernate.boot.registry.classloading.spi.ClassLoadingException： 无法在以下位置加载类 [org.h2.Driver] org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:348) 在 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.loadDriverIfPossible(DriverManagerConnectionProviderImpl.java:160) 在 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildCreator(DriverManagerConnectionProviderImpl.java:116) 在 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildPool(DriverManagerConnectionProviderImpl.java:100) 在 org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:72) 在 org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:242) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210) 在 org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:145) 在 org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66) 在 org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) 在 org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88) 在 org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:259) ... 16 更多原因：java.lang.ClassNotFoundException：无法 加载请求的类：org.h2.Driver at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl$AggregatedClassLoader.findClass(ClassLoaderServiceImpl.java:336) 在 java.lang.ClassLoader.loadClass(ClassLoader.java:424) 在 java.lang.ClassLoader.loadClass(ClassLoader.java:357) 在 java.lang.Class.forName0（本机方法）在 java.lang.Class.forName(Class.java:348) 在 org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:345) ... 28 更多
##### Initial SessionFactory 创建失败.org.hibernate.service.spi.ServiceException: 无法创建请求的服务 [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] 线程“主”java.lang.ExceptionInInitializerError 中的异常： 连接数据库错误！在 orm.hibernate.employees.HibernateUtils.(HibernateUtils.java:17) 在 orm.hibernate.employees.EmployeeRepository.addNewEmployee(EmployeeRepository.java:16) 在 orm.hibernate.employees.EmployeesApp.main(EmployeesApp.java:21)
进程以退出代码 1 结束
pom.xml：
<?xml version="1.0" encoding="UTF-8"?>
<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>brudnopis.com</groupId>
<artifactId>brudnopis2</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.2.12.Final</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.h2database/h2 -->
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.4.196</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
休眠实用程序类：
public class HibernateUtils
private static final SessionFactory sessionFactory;
static
try
sessionFactory = new Configuration().configure("hibernate.cfg.xml").buildSessionFactory();
catch (Throwable ex)
ex.printStackTrace();
System.err.println("########### Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError("Connection to database error!");
public static Session openSession() throws Exception
Session session;
try
session = sessionFactory.openSession();
catch (Exception e)
e.printStackTrace();
throw new Exception("Connection to database error!");
return session;
public static void closeSession()
sessionFactory.close();
存储库
public class EmployeeRepository
// Create
public static void addNewEmployee(EmployeeEntity employee)
Session session = null;
try
session = HibernateUtils.openSession();
session.getTransaction().begin();
session.saveOrUpdate(employee);
session.getTransaction().commit();
catch (Exception e)
e.printStackTrace();
finally
if (session != null && session.isOpen())
session.close();
// Read
public static List<EmployeeEntity> listAllEmployees()
List<EmployeeEntity> listEmployees = new ArrayList<EmployeeEntity>();
Session session = null;
try
session = HibernateUtils.openSession();
listEmployees = session.createQuery("SELECT e FROM EmployeeEntity e").getResultList();
catch (Exception e)
e.printStackTrace();
finally
if (session != null && session.isOpen())
session.close();
return listEmployees;
// Update
public static void editExistingEmployee(EmployeeEntity employee)
Session session = null;
try
session = HibernateUtils.openSession();
session.getTransaction().begin();
session.merge(employee);
session.getTransaction().commit();
catch (Exception e)
e.printStackTrace();
finally
if (session != null && session.isOpen())
session.close();
//Delete
public static void deleteEmployee(int idToDelete)
Session session = null;
try
session = HibernateUtils.openSession();
EmployeeEntity employeeToDelete = session.find(EmployeeEntity.class, idToDelete);
session.getTransaction().begin();
session.remove(employeeToDelete);
session.getTransaction().commit();
catch (Exception e)
e.printStackTrace();
finally
if (session != null && session.isOpen())
session.close();
实体类：
@Entity
@Table(name = "employees")
public class EmployeeEntity
@Id
@Column(name = "id")
private int id;
@Column(name = "employee_id")
private int employeeId;
@Column(name = "first_name")
private String firstName;
@Column(name = "last_name")
private String lastName;
public EmployeeEntity(int id, int employeeId, String firstName, String lastName)
this.id = id;
this.employeeId = employeeId;
this.firstName = firstName;
this.lastName = lastName;
public EmployeeEntity()
@Override
public String toString()
return "EmployeeEntity" +
"id=" + id +
", employeeId=" + employeeId +
", firstName='" + firstName + '\'' +
", lastName='" + lastName + '\'' +
'';
public int getId()
return id;
public void setId(int id)
this.id = id;
public int getEmployeeId()
return employeeId;
public void setEmployeeId(int employeeId)
this.employeeId = employeeId;
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;
主类：
public class EmployeesApp
public static void main(String[] args) throws Exception
Scanner sc = new Scanner(System.in);
System.out.println("Menu");
System.out.println("====");
System.out.println("1. Write data to database");
System.out.println("2. Read data from database");
System.out.println("3. Exit");
int userChoice = sc.nextInt();
switch(userChoice)
case 1:
EmployeeEntity employee1 = new EmployeeEntity(1,10001,"Jon", "Doe");
EmployeeRepository.addNewEmployee(employee1);
System.out.println(EmployeeRepository.listAllEmployees());
case 3:
break;
HibernateUtils.closeSession();
项目结构：
【问题讨论】：
您介意发布e.printStackTrace() 结果而不是throw new Exception("Connection to database error!");
顺便说一句，抛出一个新的Exception 丢弃原来的错误是一种不好的做法，你丢弃原来的错误并用随机消息覆盖它，不知道你的应用程序崩溃的真正原因
谢谢你的观点，@ngueno 我已经添加了 e.printStackTrace() 并更新了消息。也许现在它会告诉你更多。
你去我的朋友，你的错误：Caused by: java.lang.ClassNotFoundException: Could not load requested class : org.h2.Driver
是的，我对此感到困惑，因为这个驱动程序类在库中可用。范围错了：）谢谢你的回答和帮助！
【参考方案1】：
您的应用程序在运行时无法找到您的数据库驱动程序，因此出现错误Caused by: java.lang.ClassNotFoundException: Could not load requested class : org.h2.Driver。
将您的 H2 依赖项更改如下：
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.4.196</version>
<scope>runtime</scope> <!-- Here you are saying this dependency is needed at runtime, not just at testing -->
</dependency>
再见！
【讨论】：
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