MD5加密

MD5加密 - 雲代碼 http://yuncode.net/code/c_50b460ae6791910

 

 

import java.security.MessageDigest;

/**
 * 對密碼進行加密和驗證的程序
 */
public class Password {

    /** 十六進制下數字到字符的映射數組 */
    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

    /**
     * 把inputString加密。
     *
     * @param inputString
     *            待加密的字符串
     * @return
     */
    public static String createPassword(String inputString) {
        return encodeByMD5(inputString);
    }

    /**
     * 驗證輸入的密碼是否正確
     *
     * @param password
     *            真正的密碼（加密後的真密碼）
     * @param inputString
     *            輸入的字符串
     * @return
     */
    public static boolean authenticatePassword(String password,
            String inputString) {
        if (password.equals(encodeByMD5(inputString))) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * 對字符串進行MD5編碼
     *
     * @param originString
     * @return
     */
    private static String encodeByMD5(String originString) {
        if (originString != null) {
            try {
                MessageDigest md = MessageDigest.getInstance("MD5");
                byte[] results = md.digest(originString.getBytes());
                String resultString = byteArrayToHexString(results);
                return resultString.toUpperCase();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 轉換字節數組爲16進制字串
     *
     * @param b
     *            字節數組
     * @return 十六進制字串
     */
    private static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    /**
     * 將一個字節轉化成16進制形式的字符串
     *
     * @param b
     * @return
     */
    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n = 256 + n;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static void main(String[] args) {
        String password = Password.createPassword("888888");
        System.out.println("對888888用MD5摘要後的字符串：" + password);
        String inputString = "8888";
        System.out.println("8888與密碼匹配？"
                + Password.authenticatePassword(password, inputString));
        inputString = "888888";
        System.out.println("888888與密碼匹配？"
                + Password.authenticatePassword(password, inputString));
    }
}