Connect to remote MySQL database through SSH using Java

How can I connect to remote MySQL database through SSH from java application? Small code example is helpful for me and I'd apprecia开发者_如何学Gote this.

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My understanding is that you want to access a mysql server running on a remote machine and listening on let's say port 3306 through a SSH tunnel.

To create such a tunnel from port 1234 on your local machine to port 3306 on a remote machine using the command line ssh client, you would type the following command from your local machine:

ssh -L 1234:localhost:3306 mysql.server.remote

To do the same thing from Java, you could use JSch, a Java implementation of SSH2. From its website:

JSch allows you to connect to an sshd server and use port forwarding, X11 forwarding, file transfer, etc., and you can integrate its functionality into your own Java programs. JSch is licensed under BSD style license.

For an example, have a look at PortForwardingL.java. Once the session connected, create your JDBC connection to MySQL using something like jdbc:mysql://localhost:1234/[database] as connection URL.

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My detail code is below:

package mypackage;
import java.sql.*;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;

public class UpdateMySqlDatabase {
    static int lport;
    static String rhost;
    static int rport;
    public static void go(){
        String user = "ripon";
        String password = "wasim";
        String host = "myhost.ripon.wasim";
        int port=22;
        try
            {
            JSch jsch = new JSch();
            Session session = jsch.getSession(user, host, port);
            lport = 4321;
            rhost = "localhost";
            rport = 3306;
            session.setPassword(password);
            session.setConfig("StrictHostKeyChecking", "no");
            System.out.println("Establishing Connection...");
            session.connect();
            int assinged_port=session.setPortForwardingL(lport, rhost, rport);
            System.out.println("localhost:"+assinged_port+" -> "+rhost+":"+rport);
            }
        catch(Exception e){System.err.print(e);}
    }
    public static void main(String[] args) {
        try{
            go();
        } catch(Exception ex){
            ex.printStackTrace();
        }
          System.out.println("An example for updating a Row from Mysql Database!");
          Connection con = null;
          String driver = "com.mysql.jdbc.Driver";
          String url = "jdbc:mysql://" + rhost +":" + lport + "/";
          String db = "testDB";
          String dbUser = "wasim";
          String dbPasswd = "riponalwasim123";
          try{
          Class.forName(driver);
          con = DriverManager.getConnection(url+db, dbUser, dbPasswd);
          try{
          Statement st = con.createStatement();
          String sql = "UPDATE MyTableName " +
                  "SET email = 'ripon.wasim@smile.com' WHERE email='peace@happy.com'";

          int update = st.executeUpdate(sql);
          if(update >= 1){
          System.out.println("Row is updated.");
          }
          else{
          System.out.println("Row is not updated.");
          }
          }
          catch (SQLException s){
          System.out.println("SQL statement is not executed!");
          }
          }
          catch (Exception e){
          e.printStackTrace();
          }
          }
        }

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While the existing answers are correct, they obscure the significant code in bloats of other code.

This is the basic code you need to tunnel your JDBC (or any other) database connection through an SSH channel:

String jumpserverHost = "ssh.example.com";
String jumpserverUsername = "sshuser";
// The hostname/IP address and port, you would use on the SSH server
// to connect to the database.
// If the database runs on the same machine as the SSH server, use "localhost".
String databaseHost = "database.example.com";
int databasePort = 3306;
String databaseUsername = "dbuser";
String databasePassword = "dbpass";

JSch jsch = new JSch();
// Public key authentication example
// (but you can use password authentication, if appropriate).
jsch.addIdentity("~/.ssh/id_rsa");

// Connect to SSH jump server (this does not show an authentication code)
Session session = jsch.getSession(jumpserverUsername, jumpserverHost);
session.connect();

// Forward randomly chosen local port through the SSH channel to database host/port
int forwardedPort = session.setPortForwardingL(0, databaseHost, databasePort);

// Connect to the forwarded port (the local end of the SSH tunnel)
// If you don't use JDBC, but another database client,
// just connect it to the localhost:forwardedPort
String url = "jdbc:mysql://localhost:" + forwardedPort;
Connection con =
    DriverManager.getConnection(url, databaseUsername, databasePassword);

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You will also have to deal with host key verification. For that see:
How to resolve Java UnknownHostKey, while using JSch SFTP library?

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import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;

public class CTestDriver {
    private static void doSshTunnel(String strSshUser, String strSshPassword, String strSshHost, int nSshPort,
            String strRemoteHost, int nLocalPort, int nRemotePort) throws JSchException {
        final JSch jsch = new JSch();
        Session session = jsch.getSession(strSshUser, strSshHost, 22);
        session.setPassword(strSshPassword);

        final Properties config = new Properties();
        config.put("StrictHostKeyChecking", "no");
        session.setConfig(config);

        session.connect();
        session.setPortForwardingL(nLocalPort, strRemoteHost, nRemotePort);
    }

    public static void main(String[] args) {
        try {
            String strSshUser = "ssh_user_name"; // SSH loging username
            String strSshPassword = "abcd1234"; // SSH login password
            String strSshHost = "your.ssh.hostname.com"; // hostname or ip or
                                                            // SSH server
            int nSshPort = 22; // remote SSH host port number
            String strRemoteHost = "your.database.hostname.com"; // hostname or
                                                                    // ip of
                                                                    // your
                                                                    // database
                                                                    // server
            int nLocalPort = 3366; // local port number use to bind SSH tunnel
            int nRemotePort = 3306; // remote port number of your database
            String strDbUser = "db_user_name"; // database loging username
            String strDbPassword = "4321dcba"; // database login password

            CTestDriver.doSshTunnel(strSshUser, strSshPassword, strSshHost, nSshPort, strRemoteHost, nLocalPort,
                    nRemotePort);

            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:" + nLocalPort, strDbUser,
                    strDbPassword);
            con.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.exit(0);
        }
    }
}

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package framework.restapi.utils;

import java.sql.*;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

import java.sql.Connection;
import java.util.ArrayList;
import java.util.List;

public class SQLConnection {
    private static Connection connection = null;
    private static Session session = null;

    private static void connectToServer(String dataBaseName) throws SQLException {
        connectSSH();
        connectToDataBase(dataBaseName);
    }

    private static void connectSSH() throws SQLException {
        String sshHost = "";
        String sshuser = "";
        String dbuserName = "";
        String dbpassword = "";
        String SshKeyFilepath = "/Users/XXXXXX/.ssh/id_rsa";

        int localPort = 8740; // any free port can be used
        String remoteHost = "127.0.0.1";
        int remotePort = 3306;
        String localSSHUrl = "localhost";
        /***************/
        String driverName = "com.mysql.jdbc.Driver";

        try {
            java.util.Properties config = new java.util.Properties();
            JSch jsch = new JSch();
            session = jsch.getSession(sshuser, sshHost, 22);
            jsch.addIdentity(SshKeyFilepath);
            config.put("StrictHostKeyChecking", "no");
            config.put("ConnectionAttempts", "3");
            session.setConfig(config);
            session.connect();

            System.out.println("SSH Connected");

            Class.forName(driverName).newInstance();

            int assinged_port = session.setPortForwardingL(localPort, remoteHost, remotePort);

            System.out.println("localhost:" + assinged_port + " -> " + remoteHost + ":" + remotePort);
            System.out.println("Port Forwarded");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void connectToDataBase(String dataBaseName) throws SQLException {
        String dbuserName = "sf2_showpad_biz";
        String dbpassword = "lOAWEnL3K";
        int localPort = 8740; // any free port can be used
        String localSSHUrl = "localhost";
        try {

            //mysql database connectivity
            MysqlDataSource dataSource = new MysqlDataSource();
            dataSource.setServerName(localSSHUrl);
            dataSource.setPortNumber(localPort);
            dataSource.setUser(dbuserName);
            dataSource.setAllowMultiQueries(true);

            dataSource.setPassword(dbpassword);
            dataSource.setDatabaseName(dataBaseName);

            connection = dataSource.getConnection();

            System.out.print("Connection to server successful!:" + connection + "\n\n");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    private static void closeConnections() {
        CloseDataBaseConnection();
        CloseSSHConnection();
    }

    private static void CloseDataBaseConnection() {
        try {
            if (connection != null && !connection.isClosed()) {
                System.out.println("Closing Database Connection");
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }

    private static void CloseSSHConnection() {
        if (session != null && session.isConnected()) {
            System.out.println("Closing SSH Connection");
            session.disconnect();
        }
    }


    // works ONLY FOR  single query (one SELECT or one DELETE etc)
    private static ResultSet executeMyQuery(String query, String dataBaseName) {
        ResultSet resultSet = null;

        try {
            connectToServer(dataBaseName);
            Statement stmt = connection.createStatement();
            resultSet = stmt.executeQuery(query);
            System.out.println("Database connection success");
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return resultSet;
    }

    public static void DeleteOrganisationReferencesFromDB(String organisationsLike) {
        try {
            connectToServer("ServerName");
            Statement stmt = connection.createStatement();

            ResultSet resultSet = stmt.executeQuery("select * from DB1");

            String organisationsToDelete = "";
            List<String> organisationsIds = new ArrayList<String>();

            // create string with id`s values to delete organisations references
            while (resultSet.next()) {
                String actualValue = resultSet.getString("id");
                organisationsIds.add(actualValue);
            }

            for (int i = 0; i < organisationsIds.size(); i++) {
                organisationsToDelete = " " + organisationsToDelete + organisationsIds.get(i);
                if (i != organisationsIds.size() - 1) {
                    organisationsToDelete = organisationsToDelete + ", ";
                }
            }

            stmt.executeUpdate(" DELETE FROM `DB1`.`table1` WHERE `DB1`.`table1`.`organisation_id` in ( " + organisationsToDelete + " );");


        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnections();
        }
    }

    public static List<String> getOrganisationsDBNamesBySubdomain(String organisationsLike) {
        List<String> organisationDbNames = new ArrayList<String>();
        ResultSet resultSet = executeMyQuery("select `DB`.organisation.dbname from `DB1`.organisation where subdomain like '" + organisationsLike + "%'", "DB1");
        try {
            while (resultSet.next()) {
                String actualValue = resultSet.getString("dbname");
                organisationDbNames.add(actualValue);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnections();
        }
        return organisationDbNames;
    }

     public static List<String> getAllDBNames() {
        // get all live db names incentral DB
        List<String> organisationDbNames = new ArrayList<String>();
        ResultSet resultSet = executeMyQuery("show databases", "DB1");
        try {
            while (resultSet.next()) {
                String actualValue = resultSet.getString("Database");
                organisationDbNames.add(actualValue);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            closeConnections();
        }
        return organisationDbNames;
    }

      public static void deleteDataBasesByName(List<String> DataBasesNamesList) {
        try {
            connectSSH();
            int dataBasesAmount = DataBasesNamesList.size();
            for (int i = 0; i < dataBasesAmount; i++) {
                connectToDataBase(DataBasesNamesList.get(i));

                Statement stmt = connection.createStatement();
                stmt.executeUpdate("DROP database `" + DataBasesNamesList.get(i) + "`");

            }

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            CloseDataBaseConnection();
            closeConnections();
        }
    }
}

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First of all, thank you works great!

Though, I wonder if I should reuse that Session for every (potentially simultaneous) SQL Connection, or if I should create a new Session every time and only refresh it if for some reason it has expired.

Currently, I would every time I make a connection make a new instance of that Controller here and then do the SQL queries with the connection I got from it, then close it manually.

Would also be nice if I could make the class useable with try-with-resource and it closing itself. Will look into that. Cause I don´t wanna miss closing it.

That´s how the thing looks like, I'm getting DB Connections from right now.

public class ConnectionManager {

private Connection con = null;
private Session session = null;

public Connection getConnection() {
    Connection con = null;

    var settings = new DbSettingsController();

    boolean useSSH = settings.getSetting(SettingKey.UseSSH).equals("true");
    String sshPort = settings.getSetting(SettingKey.SSHPort);
    String sqlIp = settings.getSetting(SettingKey.MySqlIP);
    String sqlPort = settings.getSetting(SettingKey.MySqlPort);

    if(useSSH) {
        JSch jSch = new JSch();
        try {
            this.session = jSch.getSession(settings.getSetting(SettingKey.SSHUser),
                    settings.getSetting(SettingKey.SSHHost),
                    Integer.valueOf(sshPort));
            this.session.setPassword(settings.getSetting(SettingKey.SSHPassword));
            this.session.setConfig("StrictHostKeyChecking", "no");
            this.session.connect();
            this.session.setPortForwardingL(Integer.parseInt(sshPort), sqlIp, Integer.parseInt(sqlPort));
        } catch (JSchException e) {
            e.printStackTrace();
        }
    }

    var connectionString = String.format("jdbc:mysql://%s:%s/%s?autoReconnect=true&useSSL=false",
            sqlIp, useSSH ? sshPort : sqlPort,
            settings.getSetting(SettingKey.MySqlShema));

    var user = settings.getSetting(SettingKey.MySqlUser);
    var password = settings.getSetting(SettingKey.MySqlPassword);

    try {
        con = DriverManager.getConnection(connectionString, user, password);
    } catch (SQLException e) {
        e.printStackTrace();
    }

    return con;
}

public void close() {
    if(this.con != null) {
        try {
            this.con.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    if(this.session != null) {
        this.session.disconnect();
    }
}

If you wonder DbSettingsController I´ve made myself too, just puts settings in a Text column in a local SQLite DB, with a key assigned to it (that enum´s int value). Was just copy paste code I reused from some other project, so it was simple and fast to just do that this way.