Java Hibernate-ClassNotFoundException:com.mysql.jdbc.Driver
我试图通过Hibernate从MySQL数据库中检索数据,但遇到了以下错误:Java Hibernate-ClassNotFoundException:com.mysql.jdbc.Driver,java,mysql,hibernate,jdbc,Java,Mysql,Hibernate,Jdbc,我试图通过Hibernate从MySQL数据库中检索数据,但遇到了以下错误: Failed to create sessionFactory object.org.hibernate.service.classloading.spi.ClassLoadingException: Specified JDBC Driver com.mysql.jdbc.Driver could not be loaded java.lang.ClassNotFoundException: Could not l
Failed to create sessionFactory object.org.hibernate.service.classloading.spi.ClassLoadingException: Specified JDBC Driver com.mysql.jdbc.Driver could not be loaded
java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver
[...]
我使用一个名为DAOFactory的类来获取hibernate会话:
public class DAOFactory {
private static boolean isInstance = false;
private static SessionFactory sessionFactory;
private static ServiceRegistry serviceRegistry;
private static Session session;
private DAOFactory() throws ExceptionInInitializerError{
if( !isInstance ) {
try {
Configuration cfg = new Configuration().configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(cfg.getProperties())
.buildServiceRegistry();
sessionFactory = cfg.buildSessionFactory(serviceRegistry);
} catch (Throwable ex) {
System.err.println("Failed to create sessionFactory object."+ ex);
throw new ExceptionInInitializerError(ex);
}
session = sessionFactory.openSession();
isInstance = true ;
}
}
public static DAOFactory getInstance() {
return new DAOFactory() ;
}
public Session getSession() {
return session ;
}
}
hibernate.cfg.xml:
<?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 name="">
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/enigma</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.pool_size">1</property>
<property name="current_session_context_class">thread</property>
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="show_sql">true</property>
<property name="hbm2ddl.auto">update</property>
</session-factory>
</hibernate-configuration>
com.mysql.jdbc.Driver
jdbc:mysql://localhost:3306/enigma
根
org.hibernate.dialogue.mysqldialogue
1.
线
org.hibernate.cache.NoCacheProvider
真的
更新
并且mysql-connector-java-5.1.26-bin.jar
已经在类路径中:
有人知道我遗漏了什么吗?谢谢雷默斯的回答
mysql-connector-java-5.1.26-bin.jar
需要在运行时类路径中
运行->运行配置…->Classpath->addexternaljar
清理所有内容,再试一次,异常就会消失。对于那些使用Maven的人:在pom.xml中添加以下依赖项
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.17</version>
</dependency>
(如果不使用IDE)。在某些情况下,通过运行->运行配置将
jar
添加到classpath
可能不是合适的解决方案…->Classpath->addexternaljar
第一例
当jar
文件无法放入classpath
文件夹时,有另一种方法可以从另一个地方加载类。您只需要实例化,然后对其调用loadClass()
(前面提到过):
第二种情况
如果您想在运行时将类添加到classpath
(我更喜欢的答案是),为此,您可以创建一个非常简单的自定义类加载器,并使用唯一重写的addUrl
方法进行扩展:
public class DynamicURLClassLoader extends URLClassLoader {
public DynamicURLClassLoader(URLClassLoader classLoader) {
super(classLoader.getURLs());
}
@Override
public void addURL(URL url) {
super.addURL(url);
}
}
然后调用它:
URLClassLoader urlCL = (URLClassLoader) ClassLoader.getSystemClassLoader();
new DynamicURLClassLoader(urlCL).addURL("path_to_jar");
mysql
mysql连接器java
8.0.15
假如
- 我对Maven有着以上的依赖性
- 范围标记导致了错误
- 移除范围标签解决了这个问题
<property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
com.mysql.cj.jdbc.Driver
到
com.mysql.jdbc.Driver
下载mysql-connector-java-8.0.20.jar
从…起
将jar添加到类路径
运行->运行配置…->Classpath->addexternaljar。在mysql-connector-java-5.1.48-bin.JAR中遇到了同样的问题。为了解决这个问题,我将驱动程序类名从 com.mysql.cj.jdbc.Driver 到
com.mysql.jdbc.Driver将jar添加到运行时类路径如果您正在处理web应用程序,请将mysql-connector-java-5.1.26-bin.jar放在lib文件夹下。可能重复的可能重复的可能重复的我正在处理JPA项目,前面的两个问题没有关系。但是谢谢@Reimeus,就是这样。注意6版不再支持JDK1.7了()
URLClassLoader urlCL = (URLClassLoader) ClassLoader.getSystemClassLoader();
new DynamicURLClassLoader(urlCL).addURL("path_to_jar");
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
<scope>provided</scope>
</dependency>
<property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>