老师帮忙看看哪错了，麻烦啦

package com.jdbc_demos.demo1;

import java.sql.Connection;

import java.sql.Statement;

import org.junit.Test;

import com.jdbc_demos.utils.JDBCUtils;

public class Demo3 {

/**

* 保存记录

*/

@Test

public void demo1() {

Connection conn = null;

Statement  stmt = null;

//获得连接

try {

//获得连接

conn = JDBCUtils.getConnection();

//创建执行sql的对象

stmt = conn.createStatement();

//编写sql

String sql = "insert stu values(null,'vehe',112)";

int num = stmt.executeUpdate(sql);

if(num > 0) {

System.out.println("保存成功！");

}

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

JDBCUtils.release(stmt, conn);

}

}

}

============================================================

package com.jdbc_demos.utils;

import java.io.IOException;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Properties;

/**

 * JDBC工具类

 * @author 10570

 *

 */

public class JDBCUtils {

private static final String diverClass;

private static final String url;

private static final String username;

private static final String password;

static {

//加载属性文件并分析

Properties props = new Properties();

//如何获取属性文件的输入流？

//通常情况下使用类的加载器的方式进行获取

InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("jdbc.properies");

try {

props.load(is);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

diverClass = props.getProperty("diverClass");

url = props.getProperty("url"); 

username = props.getProperty("username");

password = props.getProperty("password");

}

/**

* 注册驱动的方法

* @throws ClassNotFoundException 

* 

*/

public static void loadDriver() throws ClassNotFoundException {

Class.forName(diverClass);

}

/**

* 获得连接方法

* @throws Exception 

*/

public static Connection getConnection() throws Exception {

loadDriver();

Connection conn =  DriverManager.getConnection(url,username,password);

return conn;

}

/**

* 释放资源

*/

public static void release(Statement stmt,Connection conn) {

if(stmt != null) {

try {

stmt.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

stmt = null;

}

if(conn != null) {

try {

conn.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

conn = null;

}

}

public static void release(ResultSet rs,Statement stmt,Connection conn) {

if(rs != null) {

try {

rs.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

rs = null;

}

if(stmt != null) {

try {

stmt.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

stmt = null;

}

if(conn != null) {

try {

conn.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

conn = null;

}

}

}

============================================================

diverClass = com.mysql.cj.jdbc.Driver

url = jdbc:mysql:///king?useSSL=false&serverTimezone=Hongkong&useUnicode=true&characterEncoding=utf-8

username = root

password = 19980915