Grammar

aes256 암호화 복호화#

Cbc사용

PKCS5PaddingPKCS7Padding

fun encryptCBC(strToEncrypt: String, key: String, iv: String): String {
    try {

        val ivParameterSpec = IvParameterSpec(iv.toByteArray())
        val secretKey = SecretKeySpec(key.toByteArray(), "AES")

        val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec)

        val crypted = cipher.doFinal(strToEncrypt.toByteArray())
        val encodedByte = Base64.encode(crypted, Base64.DEFAULT)

        return String(encodedByte)

    } catch (e: Exception) {
        Log.e("Exception", "Exception : ${e.message}")
    }
    return ""
}

fun decryptCBC(strToDecrypt: String, key: String, iv: String): String {

    val ivParameterSpec = IvParameterSpec(iv.toByteArray())
    val secretKey = SecretKeySpec(key.toByteArray(), "AES")

    val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
    cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameterSpec)

    val decodedByte = Base64.decode(strToDecrypt, Base64.DEFAULT)
    val byteResult = cipher.doFinal(decodedByte)

    return String(byteResult)
}

object AESEncyption {

    const val secretKey = "tK5UTui+DPh8lIlBxya5XVsmeDCoUl6vHhdIESMB6sQ="
    const val salt = "QWlGNHNhMTJTQWZ2bGhpV3U=" // base64 decode => AiF4sa12SAfvlhiWu
    const val iv = "bVQzNFNhRkQ1Njc4UUFaWA==" // base64 decode => mT34SaFD5678QAZX

    fun encrypt(strToEncrypt: String) : String?
    {
        try
        {
            val ivParameterSpec = IvParameterSpec(Base64.decode(iv, Base64.DEFAULT))

            val factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1")
            val spec =  PBEKeySpec(secretKey.toCharArray(), Base64.decode(salt, Base64.DEFAULT), 10000, 256)
            val tmp = factory.generateSecret(spec)
            val secretKey =  SecretKeySpec(tmp.encoded, "AES")

            val cipher = Cipher.getInstance("AES/CBC/PKCS7Padding")
            cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec)
            return Base64.encodeToString(cipher.doFinal(strToEncrypt.toByteArray(Charsets.UTF_8)), Base64.DEFAULT)
        }
        catch (e: Exception)
        {
            println("Error while encrypting: $e")
        }
        return null
    }

    fun decrypt(strToDecrypt : String) : String? {
        try
        {
            val ivParameterSpec =  IvParameterSpec(Base64.decode(iv, Base64.DEFAULT))

            val factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1")
            val spec =  PBEKeySpec(secretKey.toCharArray(), Base64.decode(salt, Base64.DEFAULT), 10000, 256)
            val tmp = factory.generateSecret(spec);
            val secretKey =  SecretKeySpec(tmp.encoded, "AES")

            val cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
            cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameterSpec);
            return  String(cipher.doFinal(Base64.decode(strToDecrypt, Base64.DEFAULT)))
        }
        catch (e : Exception) {
            println("Error while decrypting: $e");
        }
        return null
    }
}

Gcm사용

encryptdecrypt

fun encrypt(password: String): String {
    val secretKeySpec = SecretKeySpec(password.toByteArray(), "AES")
    val iv = ByteArray(16)
    val charArray = password.toCharArray()
    for (i in 0 until charArray.size){
        iv[i] = charArray[i].toByte()
    }
    val ivParameterSpec = IvParameterSpec(iv)

    val cipher = Cipher.getInstance("AES/GCM/NoPadding")
    cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec)

    val encryptedValue = cipher.doFinal(this.toByteArray())
    return Base64.encodeToString(encryptedValue, Base64.DEFAULT)
}

fun decrypt(password: String): String {
    val secretKeySpec = SecretKeySpec(password.toByteArray(), "AES")
    val iv = ByteArray(16)
    val charArray = password.toCharArray()
    for (i in 0 until charArray.size){
        iv[i] = charArray[i].toByte()
    }
    val ivParameterSpec = IvParameterSpec(iv)

    val cipher = Cipher.getInstance("AES/GCM/NoPadding")
    cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec)

    val decryptedByteValue = cipher.doFinal(Base64.decode(this, Base64.DEFAULT))
    return String(decryptedByteValue)
}

구글 인앱결제시 priceAmountMicros 에서 Float 으로 변환#

SkuDetails.priceAmountMicros 의 대한 설명:

priceAmountMicros to float 으로 변환후 소수점 3번째짜리에서 반올림

JAVAKotlin

public float getPrice(SkuDetails item) {
    double price = item.getPriceAmountMicros() / 1000000.0;
    return (float) (Math.round(price*1e2)/1e2);
}

fun getPrice(item: SkuDetails) : Float {
    val price = item.priceAmountMicros / 1000000.0
    return (round(price*100)/100).toFloat()
}

context extension#

유틸함수

앱이 설치되었는지 판단하는 함수특정 앱을 실행하는 함수마켓으로 이동하는 함수

fun Context.isInstalledApp(packageName: String): Boolean {
    val intent = packageManager.getLaunchIntentForPackage(packageName)
    return intent != null
}

fun Context.openApp(packageName: String) {
    val intent = packageManager.getLaunchIntentForPackage(packageName)
    startActivity(intent)
}

fun Context.market(packageName: String): Boolean {
    return try {
        val intent = Intent(Intent.ACTION_VIEW)
        intent.data = Uri.parse("market://details?id=$packageName")
        startActivity(intent)
        true
    } catch (e: ActivityNotFoundException) {
        e.printStackTrace()
        false
    }
}

문자열내에 $ 출력하기#

const val HashKey = "\$"

Android Language Code#

zh_cn (간체)
zh_tw (번체)

Reference

https://developers.google.com/interactive-media-ads/docs/sdks/android/client-side/localization

enum 재정의#

public enum ApiResponseCode {

    /**
     * The request was successful.
     */
    SUCCESS(1000),
    /**
     * The request was canceled.
     */
    CANCEL(1001),
    /**
     * A network error occurred.
     */
    NETWORK_ERROR(1002);

    int value;

    ApiResponseCode(int value) {
        this.value = value;
    }
    public int getValue() {
        return value;
    }
}

문자열 분리#

String lang = "kr/en/jp";
String[] arr = lang.split("/");

md5, sha256 로 암호화#

Md5

JAVAKotlin

public static String md5(String str){
    String MD5 = "";
    try{
        MessageDigest md = MessageDigest.getInstance("MD5");
        md.update(str.getBytes("UTF-8"));
        byte byteData[] = md.digest();
        StringBuffer sb = new StringBuffer();
        for(int i = 0 ; i < byteData.length ; i++)
            sb.append(Integer.toString((byteData[i]&0xff) + 0x100, 16).substring(1));
        MD5 = sb.toString();
    }
    catch(NoSuchAlgorithmException e) { e.printStackTrace(); MD5 = null; }
    catch (UnsupportedEncodingException e) { e.printStackTrace(); MD5 = null; }
    return MD5;
}

private fun md5(input:String): String {
    val md = MessageDigest.getInstance("MD5")
    return BigInteger(1, md.digest(input.toByteArray())).toString(16).padStart(32, '0')
}

Sha256

JAVAKotlin

public static String sha256(String str) {
    String SHA = "";
    try{
        MessageDigest sh = MessageDigest.getInstance("SHA-256");
        sh.update(str.getBytes());
        byte byteData[] = sh.digest();
        StringBuffer sb = new StringBuffer();
        for(int i = 0 ; i < byteData.length ; i++)
            sb.append(Integer.toString((byteData[i]&0xff) + 0x100, 16).substring(1));
        SHA = sb.toString();
    }catch(NoSuchAlgorithmException e) { e.printStackTrace(); SHA = null; }
    return SHA;
}

fun sha256(s: String): String {
    val md = MessageDigest.getInstance("SHA-256")
    val digest = md.digest(s.toByteArray())
    val hash = StringBuilder()
    for (c in digest) {
        hash.append(String.format("%02x", c))
    }
    return hash.toString()
}

Reference

https://stackoverflow.com/questions/64171624/how-to-generate-an-md5-hash-in-kotlin

UTC Time 가져오기#

private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss.SSSSSSS";

public static Date getUtcDatetimeAsDate()
{
    return stringDateToDate(getUtcDatetimeAsString());
}
// UTC Now Time get
public static String getUtcDatetimeAsString()
{
    final SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
    sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
    final String utcTime = sdf.format(new Date());

    return utcTime;
}
// DATE_FORMAT 형태의 string 을 Date 로 return
public static Date stringDateToDate(String strDate)
{
    Date dateToReturn = null;
    SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);

    try{
        dateToReturn = (Date)dateFormat.parse(strDate);
    }catch (ParseException e) {
        e.printStackTrace();
    }

    return dateToReturn;
}

millisecond to Date, String 로 변환#

private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";

//long형 타임을 String으로 변환.
public static String longTimeToDatetimeAsString(long resultTime)
{
    SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);
    String formatTime = dateFormat.format(resultTime);
    return formatTime;
}
//long형 타임을 Date 로 변환.
public static Date setTimeConvertDate(long time)
{
    Date unixDate = null;
    SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);
    String formatTime = dateFormat.format(time);
    unixDate = stringDateToDate(formatTime);

    return unixDate;
}
// 서버에서 주는 utc string을 getTime형태로 변환 후 현재시간과 차로 offset 계산.
public static long serverUTCParse(String utc)
{
    Date serverDate = null;
    SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);

    SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);
    dateFormat.setTimeZone(TimeZone.getTimeZone("utc"));
    String formatTime = null;

    try{
        serverDate = (Date)sdf.parse(utc);
        formatTime = dateFormat.format(serverDate.getTime());

        serverDate = stringDateToDate(formatTime);
    }catch (ParseException e) {
        e.printStackTrace();;
    }

    long timeOffset = serverDate.getTime() - getUtcDatetimeAsDate().getTime(); //서버시간-현재시간

    return timeOffset;
}

Timezone#

public static String getTimeZone() {

        TimeZone timeZone = TimeZone.getDefault();
        Calendar calendar = GregorianCalendar.getInstance(timeZone);
        int offsetInMillis = timeZone.getOffset(calendar.getTimeInMillis());

        Log.v("gmt offset(sec)", String.valueOf(offsetInMillis));

        //초에서 분으로 환산
        String offset = String.format(Locale.getDefault(),"%02d",
                Math.abs((offsetInMillis / 60000)));
        Log.v("gmt offset(min)", offset);
        offset = (offsetInMillis >= 0 ? "+" : "-") + offset;

        String strGmt = timeZone.getDisplayName(false,TimeZone.SHORT);
        String strId = timeZone.getID();

        String strTimeZone = String.format("Local;%s;(%s) Local Time;%s;", offset, strGmt, strId);

        return strTimeZone;
}
//gmt offset(sec): 32400000
//gmt offset(min): 540
//Local;+540;(GMT+09:00) Local Time;Asia/Seoul;

UUID 생성하기#

public static String getUUID() {        
        return UUID.randomUUID().toString();
}
//output : 2b2204c3-762f-4aae-8d50-241ad7a2dbae

DeviceName 가져오기#

public static String getDeviceModel() {
        return String.format("%s %s", Build.BRAND, Build.MODEL);
}

DeviceID 가져오기#

유니티엔진에서 제공하는 deviceUniqueIdentifier 와 동일하게 만들어줍니다. (md5 함수로 이동)

public static String getDeviceId(Context context) {   
   String deviceId = "";

   String android_id = Settings.Secure.getString(
            context.getContentResolver(),
            Settings.Secure.ANDROID_ID);
   deviceId = md5Encode(android_id);

   return deviceId;
}

string to enum 문자열을 열거형으로 변환#

Example

JAVAKotlin

public enum MyEnum {
    EnumValue1,
    EnumValue2;

    public static MyEnum fromInteger(int x) {
        switch(x) {
        case 0:
            return EnumValue1;
        case 1:
            return EnumValue2;
        }
        return null;
    }
}

enum class Types(val value: Int) {
    FOO(1),
    BAR(2),
    FOO_BAR(3);

    companion object {
        fun fromInt(value: Int) = Types.values().first { it.value == value }
    }
}

Reference

https://stackoverflow.com/questions/5878952/cast-int-to-enum-in-java

https://stackoverflow.com/questions/53523948/how-do-i-create-an-enum-from-an-int-in-kotlin

절대값 구하기#

JAVAKotlin

Math.abs(int a);

Math.abs(int a);

국가코드 및 국가명 가져오기#

JAVAKotlin

public static String getCountry() {
    return Locale.getDefault().getCountry();
}
public static String getDisplayCountry() {
        return Locale.getDefault().getDisplayCountry(Locale.US);
}

fun getCountry(): String {    
    return Locale.getDefault().country
}
fun getDisplayCountry(): String {    
    return Locale.getDefault().displayLanguage
}

언어코드 가져오기#

JAVAKotlin

public static String getLanguage() {
    return Locale.getDefault().getLanguage();
}

fun getLanguage(): String {    
    return Locale.getDefault().language
}

Grammar

aes256 암호화 복호화#

구글 인앱결제시 priceAmountMicros 에서 Float 으로 변환#

context extension#

문자열내에 $ 출력하기#

Android Language Code#

enum 재정의#

문자열 분리#

md5, sha256 로 암호화#

UTC Time 가져오기#

millisecond to Date, String 로 변환#

Timezone#

UUID 생성하기#

DeviceName 가져오기#

DeviceID 가져오기#

string to enum 문자열을 열거형으로 변환#

절대값 구하기#

국가코드 및 국가명 가져오기#

언어코드 가져오기#

Comments