字符串加/解密 Base64 & MD5 & S

/**
 * Base64 编码
 */
public static String toBase64(String string) {
    byte[] b = null;
    String result = null;
    try {
        b = string.getBytes("utf-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    if (b != null) {
        result = Base64.encodeToString(b, Base64.DEFAULT);
    }
    return result;
}

/**
 * Base64 解码
 */
public static String fromBase64(String string) {
    byte[] b;
    String result = null;
    if (string != null) {
        try {
            b = Base64.decode(string, Base64.DEFAULT);
            result = new String(b, "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    return result;
}

/**
 * 字符串 MD5 加密
 */
public static String md5(String string) {
    if (string == null) {
        return "";
    }
    try {
        MessageDigest md5 = MessageDigest.getInstance("MD5");
        byte[] bytes = md5.digest(string.getBytes());
        String result = "";
        for (byte b : bytes) {
            String temp = Integer.toHexString(b & 0xFF);
            if (temp.length() == 1) {
                temp = "0" + temp;
            }
            result += temp;
        }
        return result;
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return "";
}

/**
 * 字符串 SHA-1 加密
 */
public static String sha1(String string) {
    if (string == null) {
        return "";
    }
    try {
        MessageDigest sha1 = MessageDigest.getInstance("SHA-1");
        byte bytes[] = sha1.digest(string.getBytes());
        String result = "";
        for (byte b : bytes) {
            String temp = Integer.toHexString(b & 0xFF);
            if (temp.length() < 2) {
                result += "0";
            }
            result += temp;
        }
        return result;
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return "";
}