尝试使用Hibernate创建MySQL连接时发生异常

Question

在休眠状态下创建第一个应用程序时，我一直遇到异常。 我确实进行了搜索，但是提供的解决方案并没有帮助我。 由于在这里我花了很多时间，所以我在这里做的事情真奇怪。

请查看下面的内容以更好地指出问题。

学生.java

package beans;

public class Student {
    private int studentId;
    private String name;
    private int marks;
    public int getStudentId() {
        return studentId;
    }
    public void setStudentId(int studentId) {
        this.studentId = studentId;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getMarks() {
        return marks;
    }
    public void setMarks(int marks) {
        this.marks = marks;
    }


}

hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/school</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>

        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
        <property name="hbm2dll.auto">create</property>
        <property name="show_sql">true</property>

        <mapping resource="resources/Student.hbm.xml" />
    </session-factory>
</hibernate-configuration>

Student.hbm.xml

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="beans.Student" table="student" schema="school">
        <id name="studentId"/>
        <property name="name"/>
        <property name="marks"/>
    </class>
</hibernate-mapping>

Test.java

package test;

import org.hibernate.cfg.Configuration;

public class Test {
    public static void main(String[] args) {
        Configuration conf = new Configuration();
        conf.addResource("resources/hibernate.cfg.xml").buildSessionFactory();
    }
}

是的，我已经仔细检查了是否同时存在root用户名和密码，并且还创建了一个名为school的数据库，端口是3306。

例外：

WARN: HHH000342: Could not obtain connection to query metadata : The application must supply JDBC connections
Exception in thread "main" org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:244)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:208)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:217)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:723)
    at test.Test.main(Test.java:8)
Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
    at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:100)
    at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:54)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:137)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:234)
    ... 14 more

Answer 1

整！ 罪魁祸首似乎是您配置会话工厂的方式。 addResource()用于加载映射，但无提示地忽略所有其他设置。 尝试以下方法：

conf.configure(new File("resources/hibernate.cfg.xml"))
    .buildSessionFactory();

祝您项目顺利！

Answer 2

您没有调用configure方法

Configuration conf = new Configuration().configure();

添加它会起作用。

同样从休眠4开始，您可以使用ServiceRegistry进行初始化，看看文档