maven项目连接数据库失败原因之一

今天测试maven项目的时候，程序一直卡在UserService userService = new UserService()上。检查了几遍UserService这个类都没发现问题，然后系统也没报错。我就开始测试Dbconnetion这个类,这是封装了数据库连接和关闭操作的一个类，我先调用这个类的GetConnection方法 。Connection connection = Dbconnection.GetConnection();Dbconnection类代码如下：

private static String drivername = "com.mysql.jdbc.Driver";
private static String url = "jdbc:mysql://localhost:3306/wust";
private static String username = "root";
private static String password = "yq981205";

public static Connection GetConnection() {

        Connection connection = null;
        try {
            Class.forName(drivername);
            connection = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            System.out.println("加载驱动失败");
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("连接数据库失败");
        }

        return connection;
}

后来报出一个错误：Loading class ‘com.mysql.jdbc.Driver’ This is deprecated. The new driver class is ‘com.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

在网上找到了一个原因，可能是其MYSQL版本过高

我原先用的：

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>6.0.6</version>
</dependency>

后来我将MYSQL
版本改为：

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.0.4</version>
    </dependency>

结果数据库连接成功。

参考文章 maven管理工程，引入MyBatis、MySQL遇到的问题