hibernate入门会遇到的错误 Unable to create requested service

连接不上数据库 (不一定是出错在连接数据库上)
Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]

Access to DialectResolutionInfo cannot be null when ‘hibernate.dialect’ not set
这liang两个错可能同时出现

错误图示

可能出现的问题是在

检查这个文件(连接数据库相关代码)里的代码有没有出错

图片代码 （*看代码有没有出错）
<?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>
		<!-- 1. 数据库相关 -->
		<property name="connection.username">root</property>
		<property name="connection.password">123</property>
		<property name="connection.url">jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=UTF-8</property>
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
		
		<!-- 配置本地事务（No CurrentSessionContext configured!） -->
		<property name="hibernate.current_session_context_class">thread</property>
		
		<!-- 2. 调试相关 -->
		<property name="show_sql">true</property>
		<property name="format_sql">true</property>
		
		<!-- 3. 添加实体映射文件 -->
		<mapping resource="com/zking/entity/user.hbm.xml"/>
		
		
	</session-factory>
</hibernate-configuration>

还可能出错的地方是

hibernate入门测试代码

package com.zking.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

import com.zking.entity.User;

public class Test {

	public static void main(String[] args) {
		Configuration cnf = new Configuration().configure("/hibernate.cfg.xml");
		SessionFactory sessionFactory = cnf.buildSessionFactory();
		Session session =sessionFactory.openSession();
		Transaction transaction = session.beginTransaction();
		
		User user = new User();
		//新增
//		user.setUserName("zhuzhzu");
//		user.setUserPwd("123");
//		session.save(user);
		
		//修改
//		user.setId(2);
//		user.setUserName("23dddf");
//		user.setUserPwd("123ew");
//		session.update(user);
		
		//删除
//		user.setId(3);
//		session.delete(user);
		
		//查询
		user.setId(3);
		User user2 = session.get(User.class, 2);
		System.out.println(user2);
		
		transaction.commit();
		session.close();
		
		
	}
}