com.grzm.NamedUUID is a minimal class that makes it easy to create
Version 3 and Version 5 java.util.UUID values.
Version 3 and Version 5 UUIDs provide a deterministic method of representing arbitrary strings as UUIDs.
Version 3 UUIDs are based on an MD5 hash, while Version 5 uses SHA-1. As the values are hashed, as opposed to encoded, the generated UUIDs are non-reversible, other than through brute force (modulo weaknesses in the underlying algorithms).
You can use named UUIDs to map external identifiers to UUIDs in a deterministic manner which provides robustness from collisions.
Latest release: 1.0.0
Maven dependency coordinates
<dependency>
<groupId>com.grzm</groupId>
<artifactId>named-uuid</artifactId>
<version>1.0.0</version>
</dependency>The com.grzm.NamedUUID class provides static functions to create Version 3 and Version 5 UUIDs.
It also provides constants for the namespaces provided in the specification as well as the NIL UUID.
NamedUUID.NS_DNS: fully-qualified domain names (6ba7b810-9dad-11d1-80b4-00c04fd430c8)NamedUUID.NS_URL: URLs (6ba7b811-9dad-11d1-80b4-00c04fd430c8)NamedUUID.NS_OID: ITU object identifiers (6ba7b812-9dad-11d1-80b4-00c04fd430c8)NamedUUID.NS_X500: X.500 distinguished names (6ba7b814-9dad-11d1-80b4-00c04fd430c8)NamedUUID.NIL00000000-0000-0000-0000-000000000000
Some examples;
package com.grzm;
import java.util.UUID;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
class NamedUUIDExamplesAsTest {
@Test
void examples() {
UUID exampleDotComUUID = NamedUUID.v5(NamedUUID.NS_DNS, "example.com");
assertEquals(UUID.fromString("cfbff0d1-9375-5685-968c-48ce8b15ae17"), exampleDotComUUID,
"create a UUID using the NS_DNS namespace and domain");
UUID wikipediaUUIDPageUUID = NamedUUID.v5(NamedUUID.NS_URL,
"https://en.wikipedia.org/wiki/Universally_unique_identifier");
assertEquals(UUID.fromString("e2d4a904-c7c1-5557-9c4f-7645bacf2cd2"), wikipediaUUIDPageUUID,
"create a UUID for a URL using the NS_URL namespace");
UUID yourNamespace = NamedUUID.v5(NamedUUID.NS_DNS, "yourdomain.com");
assertEquals(UUID.fromString("930bb4d3-2265-5d59-95c1-726a7647a7f0"), yourNamespace,
"create a UUID for your domain to be used as your own namespace");
UUID yourNamespaced54 = NamedUUID.v5(yourNamespace, "54");
assertEquals(UUID.fromString("c2fabdea-4cb8-5491-bcc5-ecac4a019d7b"), yourNamespaced54,
"create a UUID for a value namespaced by your domain");
UUID yourNamespaced55 = NamedUUID.v5(yourNamespace, "55");
assertEquals(UUID.fromString("1b907b1c-6886-594d-83f6-3730b120e912"), yourNamespaced55,
"create a UUID for a different value namespaced by your domain");
assertNotEquals(yourNamespaced54, yourNamespaced55,
"confirm two distinct values in same namespace are distinct");
UUID yourNamespaceV3 = NamedUUID.v3(NamedUUID.NS_DNS, "yourdomain.com");
assertEquals(UUID.fromString("3b1a8610-1692-3597-9e60-c5db58592c45"), yourNamespaceV3,
"create a Version 3 UUID for your domain");
assertNotEquals(yourNamespace, yourNamespaceV3,
"confirm Version 3 and Version 5 UUIDs for same value are distinct.");
UUID otherNamespace = NamedUUID.v5(NamedUUID.NS_DNS, "otherdomain.com");
assertEquals(UUID.fromString("8590a268-8208-588a-b261-b65a2d7f2564"), otherNamespace,
"create a UUID for another namespace");
UUID otherNamespaced54 = NamedUUID.v5(otherNamespace, "54");
assertEquals(UUID.fromString("e8d57c22-f102-542f-bec1-22887f9d93fe"), otherNamespaced54,
"create a UUID for 54 in the other namespace");
assertNotEquals(yourNamespaced54, otherNamespaced54,
"confirm the same value in two different namespaces don't collide");
}
}© 2019 Michael Glaesemann
Distributed under the MIT License.
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