io.werval.util

Class Hashids

java.lang.Object

io.werval.util.Hashids

public final class Hashids
extends Object

Generate short unique string secret identities from positive numbers.

See hashids.org. This is a Java port of the javascript version.

The Hashids's salt is used as a secret to generate unique strings using a given alphabet. Generated strings can have a minimumLength.

If you use this to obfuscates identities, do not expose your salt, alphabet nor separators to a client, client-side is not safe.

Only positive numbers are supported. All methods in this class will throw an IllegalArgumentException if a negative number is given. If you want to use negative numbers you'll have to handle prepending - to the hash string yourself and would be limited to single number hashes.

Here is sample code to handle negative numbers prepending - to them:

 Hashids hashids = new Hashids( "this is your salt" );
 long number = -1234567890;
 String enc = ( Math.abs( number ) != number ? "-" : "" ) + hashids.encodeToString( Math.abs( number ) );
 long dec = enc.startsWith( "-" ) ? -hashids.decodeLongs( enc.substring( 1 ) )[0] : hashids.decodeLongs( enc )[0];
 

Note that this isn't true Hashids anymore and that this is limited to single number hashes.

Hashids instances are thread-safe.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Hashids.Builder Hashids Builder.

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_ALPHABET Default alphabet.
static String	DEFAULT_SEPARATORS Default separators.
static long	MAX_NUMBER_VALUE Maximum number value.

Constructor Summary

Constructors

Constructor and Description
Hashids(String salt)
Hashids(String salt, int minimumLength)
Hashids(String salt, int minimumLength, String alphabet)
Hashids(String salt, int minimumLength, String alphabet, String separators)
Hashids(String salt, String alphabet)

Method Summary

Modifier and Type	Method and Description
Hashid	decode(String hash) Decrypt string.
String	decodeHex(String hash) Decrypt string to numbers as hex.
int[]	decodeInts(String hash) Decrypt string to integers.
long[]	decodeLongs(String hash) Decrypt string to longs.
Hashid	encode(long... numbers) Encrypt number(s).
String	encodeToString(int... numbers) Encrypt number(s) to string.
String	encodeToString(long... numbers) Encrypt number(s) to string.
String	encodeToString(String hexa) Encrypt hexa string to string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_ALPHABET

public static final String DEFAULT_ALPHABET

Default alphabet.

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890

See Also:

Constant Field Values

DEFAULT_SEPARATORS

public static final String DEFAULT_SEPARATORS

Default separators.

Used to prevent the generation of strings that contains rude english words.

cfhistuCFHISTU

See Also:

Constant Field Values

MAX_NUMBER_VALUE

public static final long MAX_NUMBER_VALUE

Maximum number value.

This is 9_007_199_254_740_991, or 2^53-1, or Number.MAX_VALUE-1 in Javascript. This limit is mandatory in order to ensure interoperability.

See Also:

Constant Field Values

Constructor Detail

Hashids

public Hashids(String salt)

Hashids

public Hashids(String salt,
               int minimumLength)

Hashids

public Hashids(String salt,
               String alphabet)

Hashids

public Hashids(String salt,
               int minimumLength,
               String alphabet)

Hashids

public Hashids(String salt,
               int minimumLength,
               String alphabet,
               String separators)

Method Detail

encode

public Hashid encode(long... numbers)

Encrypt number(s).

Parameters:

numbers - The number(s) to encrypt

Returns:

The Hashid instance with both number(s) and the encrypted string

encodeToString

public String encodeToString(long... numbers)

Encrypt number(s) to string.

Parameters:

numbers - The number(s) to encrypt

Returns:

The encrypted string

encodeToString

public String encodeToString(int... numbers)

Encrypt number(s) to string.

Parameters:

numbers - The number(s) to encrypt

Returns:

The encrypted string

encodeToString

public String encodeToString(String hexa)

Encrypt hexa string to string.

Parameters:

hexa - The hexa string to encrypt

Returns:

The encrypted string

decode

public Hashid decode(String hash)

Decrypt string.

Parameters:

hash - The encrypted string

Returns:

The Hashid instance with both hash and the decrypted number(s)

decodeLongs

public long[] decodeLongs(String hash)

Decrypt string to longs.

Parameters:

hash - The encrypted string

Returns:

The decrypted longs

decodeInts

public int[] decodeInts(String hash)

Decrypt string to integers.

Parameters:

hash - The encrypted string

Returns:

The decrypted integers

Throws:

IllegalArgumentException - if decoded number is out of integer range, shouldn't you be using longs instead?

decodeHex

public String decodeHex(String hash)

Decrypt string to numbers as hex.

Parameters:

hash - The encrypted string

Returns:

The decrypted numbers as hex