Question

如何通过SSH从Java应用程序连接到远程MySQL数据库？小代码示例对我很有帮助，我很感激。

Answer 1

我的理解是你想要访问在远程机器上运行的mysql服务器并通过SSH隧道监听端口3306。

要使用命令行ssh client从本地计算机上的端口1234到远程计算机上的端口3306创建此类隧道，您可以从本地计算机中键入以下命令：

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

要从Java执行相同的操作，您可以使用JSch，这是SSH2的Java实现。从其网站：

JSch允许您连接到sshd服务器并使用端口转发，X11转发，文件传输等，您可以将其功能集成到您自己的Java程序中。 JSch根据BSD风格许可证授权。

例如，请查看PortForwardingL.java。连接会话后，使用jdbc:mysql://localhost:1234/[database]之类的连接URL创建与MySQL的JDBC连接。

Answer 2

我的详细代码如下：

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();
          }
          }
        }

Answer 3

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);
        }
    }
}

Answer 4

虽然现有答案是正确的，但它们却掩盖了其他代码中的重要代码。

这是您需要通过SSH通道建立JDBC（或任何其他）数据库连接的基本代码：

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 forward 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);

您还必须处理主机密钥验证。为此，请参见：
How to resolve Java UnknownHostKey, while using JSch SFTP library?

Answer 5

首先，谢谢你的作品很棒！

尽管如此，我想知道是否应该为每个（可能同时的）SQL连接重用该Session，或者我是否应该每次都创建一个新的Session，并且只有在某些原因它已经过期时才刷新它。

目前，我每次建立连接时都会在此处创建该Controller的新实例，然后使用我从中获得的连接执行SQL查询，然后手动关闭它。

如果我可以使用try-with-resource使这个类可用并且它自己关闭也会很好。会调查一下。因为我不想错过它。

这是怎么回事，我现在正在接收DB Connections。

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();
    }
}

如果您想知道DbSettingsController我自己也做了，只需将设置放在本地SQLite DB的Text列中，并为其分配一个键（即enum的int值）。只是复制粘贴代码我从其他项目中重复使用，所以这样做很简单快捷。

使用Java通过SSH连接到远程MySQL数据库

5 个答案: