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Java 入門指南 V2.00 - Encrypt.java




Encrypt.java


/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package encryptor;

/**
 *
 * @author changkaiching
 */
public class Encrypt {
    // 密碼表字元陣列
    private char[] code = new char[26];

    // 建構子     
    public Encrypt() {
        setCode();
    }
    
    // 帶有參數的建構子
    public Encrypt(String s) {
        code = s.toCharArray();
    }

    // setter
    public void setCode() {
        int a = 0;
        int b = 0;

        while (a % 2 == 0) {
            a = (int) (Math.random() * 10);
            b = (int) (Math.random() * 10);
        }

        int x, y, m, i;
        char c = 'a';
        for (i = 0; i < 26; i++) {
            x = c;
            y = x * a + b;
            m = y % 26;
            code[i] = (char) (m + 97);
            c++;
        }
    }
    
    // getter
    public char[] getCode() {
        return code;
    }

    // 編碼的方法
    public String toEncode(String s) {
        char[] cs = s.toCharArray();
        int i, ci, d, m;
        char r;
        String rs = "";
        Character cc;
         
        for (i = 0; i < cs.length; i++) {
            if (cs[i] >= 97 && cs[i] <= 122) {
                ci = cs[i];
                m = ci - 97;
                cs[i] = code[m];
            }
        }
         
        for (i = 0; i < cs.length; i++) {
            cc = new Character(cs[i]);
            rs = rs.concat(cc.toString());
        }
         
        return rs;
    }

    // 解碼的方法
    public String toDecode(String s) {
        char[] cs = s.toCharArray();
        int i, j;
        char r;
        String rs = "";
        Character cc;
         
        for (i = 0; i < cs.length; i++) {
            if (cs[i] >= 97 && cs[i] <= 122) {
                for (j = 0; j <= code.length; j++) {
                    if (cs[i] == code[j]) {
                        cs[i] = (char) (j + 97);
                        break;
                    }
                }
            }
        }
 
        for (i = 0; i < cs.length; i++) {
            cc = new Character(cs[i]);
            rs = rs.concat(cc.toString());
        }
         
        return rs;       
    }

    // 測試的 main()
    public static void main(String[] args) { 
        Encrypt e = new Encrypt();
        System.out.println(e.getCode());
        String s = "There is no spoon";
        System.out.println(s);
        String s1 = e.toEncode(s);
        System.out.println(s1);
        String s2 = e.toDecode(s1);
        System.out.println(s2);
    }
}

the end

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