使用 SSH 连接到 MySQL 数据库未通过代码成功但通过 MySQL Workbench 成功

Question

我正在尝试使用 Java 和 SSH 隧道连接到远程（AWS 服务器）MySQL 数据库。 当尝试使用 MySQL Workbench 连接到数据库时，它是成功的：

尝试使用 Java 代码连接到 MySQL 数据库时：

public class SQL {
    private final String MYSQL_HOSTNAME_CONNECTION = EnvConf.getProperty("mysql.hostname");
    private static final String sshUser = EnvConf.getProperty("ssh.username");
    private static final String sshHost = EnvConf.getProperty("ssh.hostname");

    public static void main(String[] args) throws JSchException {
        establishSSHConnection();
        getJDBCRemoteConnection();
    }

    private static void establishSSHConnection() {
        JSch jsch = new JSch();
        Session session = null;
        try {
            jsch.addIdentity(PATH_TO_PEM_FILE);
            session = jsch.getSession(sshUser, sshHost);
            Properties config = new Properties();
            config.put("StrictHostKeyChecking", "no");
            session.setConfig(config);
            session.connect();
            Channel channel = session.openChannel("shell");
            channel.connect();
            System.out.println("Connected!!!");
        } catch (Exception e) {
            e.printStackTrace(System.out);
        }

    }

    private static Connection getJDBCRemoteConnection() {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String dbName = "dbName"
            String userName = "root";
            String password = "password";
            String hostname = "RDS_HOST_NAME";
            String port = "3306";
            String jdbcUrl = "jdbc:mysql://" + hostname + ":" + port + "/" + dbName + "?user=" + userName + "&password=" + password;
            Connection con = DriverManager.getConnection(jdbcUrl);
            return con;
        } catch (ClassNotFoundException | SQLException e) {
            System.out.println(e.toString());
        }
        return null;
    }
}

我收到下一条错误消息：

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

==============================编辑============== ================= 这是 SSH 隧道信息： ubuntu@SSH_HOSTNAME_STRING:22 并使用 Bastion PEM 文件进行身份验证。

Answer 1

好的，我已经弄清楚我的问题是什么，现在我解决了它并且它按预期工作：

首先我没有使用我在建立ssh隧道连接时创建的转发端口：

public class SQL {
    private final String MYSQL_HOSTNAME_CONNECTION = EnvConf.getProperty("mysql.hostname");
    private static final String sshUser = EnvConf.getProperty("ssh.username");
    private static final String sshHost = EnvConf.getProperty("ssh.hostname");
    private static int forwardedPort;

    public static void main(String[] args) throws JSchException {
        establishSSHConnection();
        getJDBCRemoteConnection();
    }

    private static void establishSSHConnection() {
        JSch jsch = new JSch();
        Session session = null;
        try {
            jsch.addIdentity(PATH_TO_PEM_FILE);
            session = jsch.getSession(sshUser, sshHost);
            Properties config = new Properties();
            config.put("StrictHostKeyChecking", "no");
            session.setConfig(config);
            session.connect();
            forwardedPort = session.setPortForwardingL( 0, MYSQL_HOSTNAME_CONNECTION , 3306);
            Channel channel = session.openChannel("shell");
            channel.connect();
            System.out.println("Connected!!!");
        } catch (Exception e) {
            e.printStackTrace(System.out);
        }

    }

    private static Connection getJDBCRemoteConnection() {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String dbName = "dbName"
            String userName = "root";
            String password = "password";
            
            String port = "3306";
            String jdbcUrl = "jdbc:mysql://localhost:" + forwardedPort + "/" + dbName + "?user=" + userName + "&password=" + password;

            Connection con = DriverManager.getConnection(jdbcUrl);
            return con;
        } catch (ClassNotFoundException | SQLException e) {
            System.out.println(e.toString());
        }
        return null;
    }
}