Question

所以在我的程序中我应该有一个驱动程序类和实用程序类。我必须编写一个使用与Caesar相同类型的密码学的程序。例如a = f，b = g，c = h，依此类推。在我的驱动程序类中我应该有解码和编码过程。必须使用命令行参数对文件进行加密/解密。例如，

java CaesarLab编码“关键字”message.txt

在实用程序类中，字母的移位应该是。这是我知道放置此代码的地方：

public static final int NUM_LETTERS = 26;

// shifting up for the encoding process
public static char shiftUpByK(char c, int k) {
   if ('a' <= c && c <= 'z')
       return (char) ('a' + (c - 'a' + k) % NUM_LETTERS);
   if ('A' <= c && c <= 'Z')
       return (char) ('A' + (c-'A' + k) % NUM_LETTERS);
   return c; // don't encrypt if not an alphabetic character
}

 // shifting down for the decoding process
 public static char shiftDownByK(char c, int k) {
     return shiftUpByK(c, NUM_LETTERS - k);
}

它还应该从FileInputStream中读取，并通过捕获所有I / O异常来处理异常/错误。

这个程序似乎有很多组件，我无法将它们放在一起。如果我可以帮助整理所有这些，我们将不胜感激。

Answer 1

我做了一个小骷髅让你有一个特定的想法，那些＆＃34;很多组件＆＃34;可能。你已经拥有了你的驱动程序 - 让我们说你在CaesarDriver.java中定义了它。

使用该＆＃34;驱动程序＆＃34;的实用程序现在可能看起来像这样：

import java.io.PrintWriter;
import java.util.Scanner;

/**
 * This is a utility class allows to encrypt/ decrypt the data received by a Scanner {@see Scanner} using the caesar
 * encoding by providing the key to be used.
 *
 * Note: Behind the scanner there may be a File or System.in as source
 */
public class CaesarUtility {

    /**
     * TODO: implement a mechanism to encrypt data ({@see Scanner}) and write the encrypted data out ({@see PrintWriter})
     * TODO: use the provided key for encryption
     * @param in source for the data to be encrypted {@see Scanner}
     * @param out destination for the encrypted data to be written to {@see PrintWriter}
     * @param key key to be used for the encryption
     */
    public static void encrypt (Scanner in, PrintWriter out, String key){

        // TODO: do we need to validate something? Could something be null? Do we need to care about this?

        // TODO: Read from Scanner
        String dataToEncrypt = "TODO: Read from Scanner";

        // TODO: Encryption
        String encryptedData = "Use your existing Caesar Driver with the correct method to encrypt the data";

        // TODO: Write encrpyted data using the provided PrintWriter
    }

    /**
     * TODO: The same like in encrypt but decrypt data this time
     * @param in source for the data to be decrypted {@see Scanner}
     * @param out destination for the decrypted data to be written to {@see PrintWriter}
     * @param key key to be used for the decryption
     */
    public static void decrypt (Scanner in, PrintWriter out, String key){

        // TODO: Basicially the same but for decryption (e.g. you will use your driver slightly different here :))

    }
}

允许世界使用这样的东西：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 *  Hello i am a Application that is too lazy to implement the Caesar encoding/ decoding - luckaly someone
 *  made me a Utility for that :)
 *
 *  TODO: This could need some improvement - maybe let the user type in the in/output file in the console?
 *
 */
public class Application {

    // TODO: How i said i am a bit rosty here - was it a number or a character - you know it better than i do i assume :)
    private static final String KEY = "???";

    public static void main(String[] args){
          new Application().start();
    }

    public void start(){

         // lets first encode a file - we need to have a Scanner to be able to use the Utility class (so i searched)
         // SO for "Java Scanner read File" and found this:
        File inputFile = new File("sensitive-data.txt");
        Scanner inputScanner = null;

        try {
            new Scanner(inputFile);
        } catch (FileNotFoundException e) {
            // TODO: Exception handling (does it make sence to proceed in this case? do we have to notify the user about this?
            e.printStackTrace();
        }

        // let the utility encode the file and write it to another file - luckaly searching SO for "Java PrintWriter example"
        // helps us out here
        File outFile = new File ("sensitive-data.txt");
        PrintWriter outWriter = null;
        try {
            outWriter = new PrintWriter (outFile);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        // Alright we have both - the input as well as the output and the key - its time to let the utility do its work
        CaesarUtility.encrypt(inputScanner, outWriter, KEY);

        // TODO: Whoopy i accidentially overwritten the source file with encoded data - luckaly i am able to decode it again
        // TODO: Decode the encoded file before the boss asks about the next sensitive-data report :)

    }
}

我希望这可以帮助您进一步深入挖掘任务 - 当您下次遇到所有代码时，请随时更新您的答案（至少可以让您从现在开始提出更具体的问题）你不会被投降到地面。）

Julius Caesar解密/加密，编码/解码Java程序

1 个答案: