输入流转密文

Question

.. 我的任务是实现一个输入流并返回一个密文，其中每个字符向前两个位置并且必须区分大小写。 例如：

    Test
    cipher
    For
    Fundamentals
    Of
    Programming
    XYZ
    zyx
    CamelCase
    DiScO

    cipherText(file);

    Vguv
    ekrjgt
    Hqt
    Hwpfcogpvcnu
    Qh
    Rtqitcookpi
    ZAB
    baz
    EcognEcug
    FkUeQ

这是第一个必须返回密文的类，我在那里做了一些实现：

public class CipherCreator {

private CipherCreator() {
}

public static StringBuilder cipherText(File input) throws IOException {
    StringBuilder strb = new StringBuilder();
    BufferedReader br = null;
    try {
        br = new BufferedReader(new FileReader(input));
        String str = null;
        while ((str = br.readLine()) != null) {
            strb.append(str + "\n");
        }
    }
    finally {
        if (br != null) {
            br.close();
        }
    }
    strb.setLength(strb.length() - 1);

    return strb;
}

我有第二类“TransformerInputStream”，我必须重写 read() 和 close() 方法并完成字符传输工作。

如何对字符进行加密，尤其是区分大小写的字符？

Answer 1

也许你可以让

TransformerInputStream

延长

InputStream

:

CipherCreator.java

：

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

public class CipherCreator {
  // Private constructor to prevent instantiation
  private CipherCreator() {}

  public static String cipherText(File inputFile) throws IOException {
    StringBuilder sb = new StringBuilder();
    try (BufferedReader br = new BufferedReader(new FileReader(inputFile, StandardCharsets.UTF_8));
        TransformerInputStream transformerInputStream = new TransformerInputStream(br)) {
      int ch;
      while ((ch = transformerInputStream.read()) != -1) {
        sb.append((char) ch);
      }
    }
    return sb.toString();
  }
}

TransformerInputStream.java

：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;

public class TransformerInputStream extends InputStream {
  private final BufferedReader reader;
  private String currentLine;
  private int charIndex;

  public TransformerInputStream(BufferedReader reader) {
    this.reader = reader;
    this.charIndex = 0;
    this.currentLine = null;
  }

  @Override
  public int read() throws IOException {
    if (currentLine == null || charIndex >= currentLine.length()) {
      currentLine = reader.readLine();
      if (currentLine == null) {
        return -1; // End of stream
      }
      currentLine += "\n"; // Re-add newline
      charIndex = 0;
    }
    char ch = currentLine.charAt(charIndex++);
    return shiftCharacter(ch);
  }

  private int shiftCharacter(char ch) {
    if (ch >= 'a' && ch <= 'z') {
      return ((ch - 'a' + 2) % 26) + 'a';
    } else if (ch >= 'A' && ch <= 'Z') {
      return ((ch - 'A' + 2) % 26) + 'A';
    } else {
      return ch; // Non-alphabetic characters remain unchanged
    }
  }

  @Override
  public void close() throws IOException {
    reader.close();
  }
}

Main.java

：

import java.io.File;
import java.io.IOException;

public class Main {
  public static void main(String[] args) {
    File inputFile = new File("src/main/java/input.txt");
    try {
      String cipheredText = CipherCreator.cipherText(inputFile);
      System.out.println(cipheredText);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

input.txt

：

Test
cipher
For
Fundamentals
Of
Programming
XYZ
zyx
CamelCase
DiScO

输出：

Vguv
ekrjgt
Hqt
Hwpfcogpvcnu
Qh
Rtqitcookpi
ZAB
baz
EcognEcug
FkUeQ