java Apache sshd断线重连

Apache SSHD 提供了重连功能的支持，可以在连接中断后自动重连。下面是一个示例代码：

public class SshClient {
    private static final Logger LOGGER = LoggerFactory.getLogger(SshClient.class);

    private final String host;
    private final int port;
    private final String username;
    private final String password;

    private SshClientSession sshClientSession;
    private boolean connected = false;

    public SshClient(String host, int port, String username, String password) {
        this.host = host;
        this.port = port;
        this.username = username;
        this.password = password;
    }

    public void connect() throws IOException, InterruptedException {
        SshClient client = SshClient.setUpDefaultClient();
        client.start();

        ConnectFuture future = client.connect(host, port);
        future.await();

        sshClientSession = future.getSession();

        sshClientSession.addPasswordIdentity(password);
        sshClientSession.auth().verify();

        connected = true;
    }

    public void disconnect() throws IOException {
        if (sshClientSession != null) {
            sshClientSession.disconnect();
        }

        connected = false;
    }

    public boolean isConnected() {
        return connected;
    }

    public SshClientSession getSshClientSession() {
        return sshClientSession;
    }

    public static void main(String[] args) throws IOException, InterruptedException {
        SshClient sshClient = new SshClient("localhost", 22, "username", "password");
        sshClient.connect();

        SshClientSession sshClientSession = sshClient.getSshClientSession();

        sshClientSession.addCloseFutureListener(new SshFutureListener<CloseFuture>() {
            @Override
            public void operationComplete(CloseFuture future) {
                LOGGER.info("Session closed, trying to reconnect...");

                while (true) {
                    try {
                        sshClient.connect();
                        LOGGER.info("Reconnected successfully.");
                        break;
                    } catch (IOException | InterruptedException e) {
                        LOGGER.info("Failed to reconnect. Retrying in 5 seconds...");
                    }

                    Thread.sleep(5000);
                }
            }
        });

        while (sshClient.isConnected()) {
            // Do something with the SSH session
        }

        sshClient.disconnect();
    }
}

在 `main()` 方法中，我们首先创建了一个 SSH 客户端 `SshClient`，并通过 `connect()` 方法连接到 SSH 服务器。然后，我们获取到 SSH 会话 `SshClientSession`，并为其添加一个关闭监听器 `SshFutureListener`。当会话关闭时，我们在监听器中尝试重新连接 SSH 服务器。如果连接失败，我们将在 5 秒钟后重试，直到连接成功为止。

在 `while (sshClient.isConnected())` 循环中，我们可以执行一些操作，例如发送命令到 SSH 服务器，或者接收来自 SSH 服务器的响应。当连接断开时，循环将退出，然后我们通过 `disconnect()` 方法关闭 SSH 客户端。

需要注意的是，上述代码中的重连逻辑仅针对 SSH 会话断开的情况。如果 SSH 客户端与 SSH 服务器之间的 TCP 连接断开，那么需要使用其他方法进行重连，例如通过 TCP Keep-Alive 或者使用一个专门的 TCP 连接池等。