caesar.java

corejava经典的java书籍

/**
   @version 1.00 1997-09-10
   @author Cay Horstmann
*/

import java.io.*;

/**
   Encrypts a file using the Caesar cipher.
*/
public class Caesar
{ 
   public static void main(String[] args)
   {  
      if (args.length != 3)
      {  
         System.out.println("USAGE: java Caesar in out key");
         return;
      }

      try
      {  
         FileInputStream in = new FileInputStream(args[0]);
         FileOutputStream out = new FileOutputStream(args[1]);
         int key = Integer.parseInt(args[2]);
         int ch;
         while ((ch = in.read()) != -1)
         {  
            byte c = (byte)(ch + key);
            out.write(c);
         }
         in.close();
         out.close();
      }
      catch (IOException exception)
      {  
         exception.printStackTrace();
      }
   }
}