在命令行上隐藏输入

Question

我知道像Git和其他命令行界面能够隐藏用户的输入(对密码很有用).有没有办法在Java中以编程方式执行此操作？我正在从用户那里获取密码输入,我希望他们的输入被"隐藏"在该特定行上(但不是所有这些).这是我的代码(虽然我怀疑它会有所帮助......)

try (Scanner input = new Scanner(System.in)) {
  //I'm guessing it'd probably be some property you set on the scanner or System.in right here...
  System.out.print("Please input the password for " + name + ": ");
  password = input.nextLine();
}

Answer 1

试试java.io.Console.readPassword.你必须至少运行Java 6.

   /**
    * Reads a password or passphrase from the console with echoing disabled
    *
    * @throws IOError
    *         If an I/O error occurs.
    *
    * @return  A character array containing the password or passphrase read
    *          from the console, not including any line-termination characters,
    *          or <tt>null</tt> if an end of stream has been reached.
    */
    public char[] readPassword() {
        return readPassword("");
    }

请注意,这不适用于Eclipse控制台.您必须从真正的控制台/ shell /终端/提示符运行该程序才能测试它.

Answer 2

是的,可以做到.这称为命令行输入掩蔽.您可以轻松实现此功能.

您可以使用单独的线程在输入时擦除回显的字符,并用星号替换它们.这是使用下面显示的EraserThread类完成的

import java.io.*;

class EraserThread implements Runnable {
   private boolean stop;

   /**
    *@param The prompt displayed to the user
    */
   public EraserThread(String prompt) {
       System.out.print(prompt);
   }

   /**
    * Begin masking...display asterisks (*)
    */
   public void run () {
      stop = true;
      while (stop) {
         System.out.print("\010*");
     try {
        Thread.currentThread().sleep(1);
         } catch(InterruptedException ie) {
            ie.printStackTrace();
         }
      }
   }

   /**
    * Instruct the thread to stop masking
    */
   public void stopMasking() {
      this.stop = false;
   }
}

使用这个线程

public class PasswordField {

   /**
    *@param prompt The prompt to display to the user
    *@return The password as entered by the user
    */
   public static String readPassword (String prompt) {
      EraserThread et = new EraserThread(prompt);
      Thread mask = new Thread(et);
      mask.start();

      BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
      String password = "";

      try {
         password = in.readLine();
      } catch (IOException ioe) {
        ioe.printStackTrace();
      }
      // stop masking
      et.stopMasking();
      // return the password entered by the user
      return password;
   }
}

本链接详细讨论.

Answer 3

JLine 2可能会引起关注.除了字符屏蔽外,它还提供命令行完成,编辑和历史记录功能.因此,它对基于CLI的Java工具非常有用.

掩盖你的输入:

String password = new jline.ConsoleReader().readLine(new Character('*'));