public class Caesar { public static final String SOURCE = "abcdefghijklmnopqrstuvwxyz"; public static final int LEN = SOURCE.length(); /** * @param args */ public static void main(String[] args) { String result = caesarEncryption("newyork"); System.out.println("encryption result:" + result); System.out.println("decryption result:" + caesarDecryption(result)); } //Encryption public static String caesarEncryption(String s) { StringBuilder sb = new StringBuilder(); if (s == null || s.length() < 1) { System.out.println("you Input nothing."); return null; } if (!isAlp(s)) { System.out.println("input ABC... only"); return null; } s = s.toLowerCase(); int len = s.length(); for (int j = 0; j < len; j++) { char c = s.charAt(j); int a = SOURCE.indexOf(c); if (a == LEN -1) a = -1; if (a == LEN -2) a = -2; if (a == LEN - 3) a = -3; sb.append(SOURCE.charAt(a + 3)); } return sb.toString(); } //Decryption public static String caesarDecryption(String s) { StringBuilder sb = new StringBuilder(); if (s == null || s.length() < 1) { System.out.println("you Input nothing."); return null; } if (!isAlp(s)) { System.out.println("input ABC... only"); return null; } s = s.toLowerCase(); for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); int a = SOURCE.indexOf(c); if (a == 2) a = LEN + 2; if (a == 1) a = LEN + 1; if (a == 0) a = LEN; sb.append(SOURCE.charAt(a - 3)); } return sb.toString(); } public static boolean isAlp(String s) { String p = "^[A-Za-z]+$"; Pattern pattern = Pattern.compile(p); Matcher matcher = pattern.matcher(s); if (matcher.find()) { return true; } return false; } }
Caesar 암호화 알고리즘의 JAVA 구현과 관련된 더 많은 기사를 보려면 PHP 중국어 웹사이트를 주목하세요!