Question

我正构建一个简单的程序，使用Ganymed for SSH2库对linux服务器执行单个命令。这是我的代码......

public class Main {

static Scanner reader = new Scanner(System.in);


public static void main(String[] args) throws IOException, InterruptedException{        


    String hostname; // = "192.168.1.241";
    int port; // = 22
    String username; // = "root";
    String password; 
    String cmd; // = "echo 'Hello World'";

    //ask user for hostname/IP
    System.out.print("Enter hostname or IP: ");
    hostname = reader.nextLine();


    //ask user for port #
    System.out.print("Enter port number: ");
    port = reader.nextInt();        

        //create connection
        Connection connect = new Connection(hostname, port);

    //ask user for username
    System.out.println("Enter Username (best to use 'root'): ");
    username = reader.nextLine();

    //ask user for password
    System.out.println("Enter Password: ");
    password = reader.nextLine();   


    System.out.println("Attempting to log in...");

    reader.close(); 

        //establish connection
        connect.connect();

        //login using password
        connect.authenticateWithPassword(username, password);

        Thread.sleep(1000);
        if (Thread.interrupted())  // Clears interrupted status!
              throw new InterruptedException();

        Boolean didConnect = connect.isAuthenticationComplete();
        if (didConnect==false){
            throw new IOException("Authentication Unsucessful \nCheck hostname and port number, then try again.");
        }

            //open session
            Session session = connect.openSession();
            System.out.println("Opened session!");              




        System.out.println("Enter a command to execute: ");
        cmd = reader.nextLine();

        //execute command
        session.execCommand(cmd);


        //get output
        InputStream stdout = new StreamGobbler(session.getStdout());

        BufferedReader br = new BufferedReader(new InputStreamReader(stdout));

        String line = br.readLine();
        if (line!=null){
            System.out.println("Command sent succesfully!" + "\nOutput: " + "\n" + "\n" + line);
        }else{
            System.out.println("Command sent succesfully!" + "\nNo Output");
        }

        //close buffered reader
        br.close();

        //close session
        session.close();

        //close connection
        connect.close();


    }



}

出于某种原因......

//ask user for username
    System.out.println("Enter Username (best to use 'root'): ");
    username = reader.nextLine();

    //ask user for password
    System.out.println("Enter Password: ");
    password = reader.nextLine();

同时打印，我不知道为什么！当使用 ln 时，当使用打印时，它也会在完全不同的行上而不是在其旁边获取用户输入。

我希望他们首先询问用户名，然后输入密码，将用户输入放在输出旁边。但是，当我要求输入主机名和端口号时，它们会单独/按顺序打印，就像我想要的那样。我做错了什么？

Answer 1

执行port = reader.nextInt();后，需要放置一个reader.nextLine()来读取具有int的行的其余部分（和换行符）。

//ask user for port #
System.out.print("Enter port number: ");
port = reader.nextInt();

reader.nextInt()在数字后面没有读取换行符或任何内容。

添加reader.nextLine()，然后应该遵循其余代码：

reader.nextLine();

//ask user for username
System.out.println("Enter Username (best to use 'root'): ");
username = reader.nextLine();

//ask user for password
System.out.println("Enter Password: ");
password = reader.nextLine();

Answer 2

您的问题是您多次使用同一个扫描仪对象来读取一行。它会跳过代码：

 //ask user for username
System.out.println("Enter Username (best to use 'root'): ");
username = reader.nextLine();

//ask user for password
System.out.println("Enter Password: ");
password = reader.nextLine();

因为该对象已经具有您正在调用的方法的值。

解决方案：每次使用时重新实例化对象：

reader = new Scanner(System.in);

System.out.println同时打印

2 个答案: