JSch 實戰：Java 程式透過 SSH 執行遠端 Linux 指令完整指南

依賴引入

<dependency>
  <groupId>com.jcraft</groupId>
  <artifactId>jsch</artifactId>
  <version>0.1.55</version>
</dependency>

核心工具類

public final class SshExecutor {
    private static final Logger log = LoggerFactory.getLogger(SshExecutor.class);
    private Session session;
    private final int timeout = 60_000;

    public void connect(String host, String user, String password, int port) throws JSchException {
        JSch jsch = new JSch();
        session = jsch.getSession(user, host, port);
        session.setPassword(password);
        session.setConfig("StrictHostKeyChecking", "no");  // 生產建議改為 known_hosts 驗證
        session.setTimeout(timeout);
        session.connect();
        log.info("SSH 連線建立：{}@{}", user, host);
    }

    public String exec(String command, String charset) throws JSchException, IOException {
        ChannelExec channel = (ChannelExec) session.openChannel("exec");
        channel.setCommand(command);
        channel.setErrStream(System.err);
        channel.connect();

        try (InputStream in = channel.getInputStream();
             BufferedReader reader = new BufferedReader(new InputStreamReader(in, Charset.forName(charset)))) {
            StringBuilder output = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                output.append(line).append('\n');
            }
            return output.toString();
        } finally {
            channel.disconnect();
        }
    }

    public void disconnect() {
        if (session != null && session.isConnected()) {
            session.disconnect();
            log.info("SSH 連線關閉");
        }
    }
}

使用範例

try (SshExecutor ssh = new SshExecutor()) {
    ssh.connect("10.8.12.189", "jmuser", "root1234", 22);
    String result = ssh.exec("java -version", "UTF-8");
    System.out.println(result);
}

生產環境關鍵強化

• 金鑰認證替代密碼：jsch.addIdentity(privateKeyPath) + session.setUserInfo
• Known Hosts 驗證：jsch.setKnownHosts(knownHostsPath)，移除 StrictHostKeyChecking=no
• 連線池化：搭配 Apache Commons Pool 2 管理 Session 物件，避免頻繁建立/銷毀
• 超時細分：連線超時、指令執行超時、閒置超時分別配置
• 日誌脫敏：輸出時過濾密碼、Token 等敏感資訊

常見異常排查