问Tomcat不与mysql数据库同步

EN

public class DriverManagerConnectionPool  {

private static List<Connection> freeDbConnections;

static {
    freeDbConnections = new LinkedList<Connection>();
    try {
        Class.forName("com.mysql.cj.jdbc.Driver");
    } catch (ClassNotFoundException e) {
        System.out.println("DB driver not found:"+ e.getMessage());
    } 
}

private static synchronized Connection createDBConnection() throws SQLException {
    Connection newConnection = null;
    String ip = "localhost";
    String port = "3306";
    String db = "storage";
    String username = "root";
    String password = "1234";

    newConnection = DriverManager.getConnection("jdbc:mysql://"+ ip+":"+ port+"/"+db+"?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC", username, password);

    newConnection.setAutoCommit(false);
    return newConnection;
}


public static synchronized Connection getConnection() throws SQLException {
    Connection connection;

    if (!freeDbConnections.isEmpty()) {
        connection = (Connection) freeDbConnections.get(0);
        freeDbConnections.remove(0);

        try {
            if (connection.isClosed())
                connection = getConnection();
        } catch (SQLException e) {
            connection.close();
            connection = getConnection();
        }
    } else {
        connection = createDBConnection();      
    }

    return connection;
}

public static synchronized void releaseConnection(Connection connection) throws SQLException {
    if(connection != null) freeDbConnections.add(connection);
}