将数据的必要字符串用String类型的变量代替
public static final String URL = "jdbc:mysql://localhost:3306/？？？?characterEncoding=utf8&useSSL=false&serverTimezone=UTC";
public static final String USER = "？？？";
public static final String PASSWORD = "？？？";
public static final String DRIVER="com.mysql.cj.jdbc.Drive";