Question

我使用https://remotemysql.com/创建了一个外部数据库，而不是使用本地的mySQL数据库。我遇到的问题是我无法连接到数据库。

这是我的休眠配置文件：

<?xml version='1.0' encoding='UTF-8'?>
<!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>
    <!-- SQL Dialect -->
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

    <!-- Database Connection Settings -->
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://www.remotemysql.com:3306/oJv6mOSx3X</property>
    <property name="hibernate.connection.username">34kjldxck</property>
    <property name="hibernate.connection.password">mysecpw</property>
    <property name="show_sql">true</property>

    <!-- Specifying Session Context -->
    <property name="hibernate.current_session_context_class">org.hibernate.context.internal.ThreadLocalSessionContext</property>

    <!-- Mapping With Model Class Containing Annotations -->
    <mapping class="com.jcg.hibernate.maven.User" />
</session-factory>

这是我尝试连接到数据库的方式：

public class AppMain {
static Session sessionObj;
static SessionFactory sessionFactoryObj;

private static SessionFactory buildSessionFactory() {
    // Creating Configuration Instance & Passing Hibernate Configuration File
    Configuration configObj = new Configuration();
    configObj.configure("hibernate.cfg.xml");

    // Since Hibernate Version 4.x, ServiceRegistry Is Being Used
    ServiceRegistry serviceRegistryObj = new StandardServiceRegistryBuilder().applySettings(configObj.getProperties()).build(); 

    // Creating Hibernate SessionFactory Instance
    sessionFactoryObj = configObj.buildSessionFactory(serviceRegistryObj);
    return sessionFactoryObj;
}

public static void main(String[] args) {
    try {
        sessionObj = buildSessionFactory().openSession(); 
    } catch(Exception ex){
                ex.printStackTrace();
    }
 }
}

这是我得到的错误：

org.hibernate.exception.JDBCConnectionException: Error calling Driver#connect
at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator$1$1.convert(BasicConnectionCreator.java:122)
at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.convertSqlException(BasicConnectionCreator.java:140)
at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:58)
at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.createConnection(BasicConnectionCreator.java:75)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:106)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.buildJdbcConnectionAccess(JdbcServicesImpl.java:260)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:94)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)
at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
at com.jcg.hibernate.maven.AppMain.buildSessionFactory(AppMain.java:24)
at com.jcg.hibernate.maven.AppMain.main(AppMain.java:30)
Caused by: java.sql.SQLException: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
at com.mysql.jdbc.ConnectionImpl.buildCollationMapping(ConnectionImpl.java:1041)
at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3481)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2445)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2215)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:813)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:55)
... 14 more
Caused by: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long
at com.mysql.jdbc.ConnectionImpl.buildCollationMapping(ConnectionImpl.java:992)
... 27 more
enter code here

现在我猜测该错误是由于我猜测的连接URL引起的。奇怪的是我得到了数学异常（igInteger无法转换为java.lang.Long）

Answer 1

这种类型的错误表示连接数据库的错误（搜索例外以获取结果）。很难说是什么原因。它可能与connector.jar的版本有关。我会进行检查，但是首先，我将检查您是否能够从休眠框架连接到本地数据库。

Answer 2

如果您向下滚动到错误，请在caused by部分中，我认为您在数据库中有一个类型为BigInteger的字段，并且该字段已映射到Long类字段，这会导致ClassCastException

希望有帮助

如何使用休眠方式与外部MySQL数据库连接

2 个答案: