java - 使用 SSH 和 Java 连接到 postgresql

Question

我正在尝试使用 JSch 在 java 中连接到 postgresql，但出现异常，我无法弄清楚问题出在哪里。我使用了本教程中提供的方法 https://www.journaldev.com/235/java-mysql-ssh-jsch-jdbc

代码及异常如下

public class MySqlConnOverSSH {
public static void main(String[] args) throws SQLException {

    int lport = 5656;
    String rhost = "192.168.1.1";
    int rport = 5432;
    String user = "abc";
    String password = "abc";
    String url = "jdbc:postgresql://localhost:" + lport + "/dbtwitter";
    String driverName = "org.postgresql.Driver";
    Connection conn = null;
    Session session = null;
    try {
        java.util.Properties config = new java.util.Properties();
        config.put("StrictHostKeyChecking", "no");
        JSch jsch = new JSch();
        session = jsch.getSession(user, rhost, 22);
        session.setPassword(password);
        session.setConfig(config);
        session.setConfig("PreferredAuthentications","publickey,keyboard-interactive,password");
        session.connect();
        System.out.println("Connected");
        int assinged_port = session.setPortForwardingL(lport, rhost, rport);
        System.out.println("localhost:" + assinged_port + " -> " + rhost + ":" + rport);
        System.out.println("Port Forwarded");

        //mysql database connectivity
        Class.forName(driverName).newInstance();
        conn = DriverManager.getConnection(url, user, password);
        System.out.println("Database connection established");
        System.out.println("DONE");
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (conn != null && !conn.isClosed()) {
            System.out.println("Closing Database Connection");
            conn.close();
        }
        if (session != null && session.isConnected()) {
            System.out.println("Closing SSH Connection");
            session.disconnect();
        }
    }
}
}

我收到以下异常

 org.postgresql.util.PSQLException: The connection attempt failed.
at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:136)
at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:66)
at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:125)
at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30)
at org.postgresql.jdbc3g.Jdbc3gConnection.<init>(Jdbc3gConnection.java:24)
at org.postgresql.Driver.makeConnection(Driver.java:382)
at org.postgresql.Driver.connect(Driver.java:260)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at evidenceofvaccine.MySqlConnOverSSH.main(MySqlConnOverSSH.java:54)
Caused by: java.io.EOFException
at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:257)
at org.postgresql.core.v3.ConnectionFactoryImpl.doAuthentication(ConnectionFactoryImpl.java:253)
at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:94)
... 9 more

Answer 1

这可能无法具体解决问题，但我在迁移一些 Java 应用程序时遇到了与 SSH 隧道类似的问题。

SSH 给了我几个问题，我发现创建连接更容易，不是在代码本身中，而是使用控制台/终端创建一个桥接，像这样:

ssh -L localhost:MY_LOCAL_PORT:MY_LOCAL_URL:MY_DB_PORT -N -J MY_LOCAL_USER -i ~/MY_LOCATION/MY_FILE_NAME.pem VM_USER

后来，我使用我的应用程序 localhost:9991 作为我的新连接，然后它按预期工作。我避免使用过于复杂的代码修改我的 Java 应用程序，并且在我看来可以以某种方式重用。