Apereo CAS Core Utilities

<dependency>
    <groupId>org.apereo.cas</groupId>
    <artifactId>cas-server-core-util-api</artifactId>
    <version>7.2.4</version>
</dependency>

// Core utility classes
import org.apereo.cas.util.CollectionUtils;
import org.apereo.cas.util.DateTimeUtils;
import org.apereo.cas.util.JsonUtils;
import org.apereo.cas.util.function.FunctionUtils;

// Cryptographic utilities  
import org.apereo.cas.util.crypto.CipherExecutor;
import org.apereo.cas.util.cipher.AbstractCipherExecutor;
import org.apereo.cas.util.serialization.SerializationUtils;

// HTTP clients
import org.apereo.cas.util.http.HttpClient;
import org.apereo.cas.util.http.SimpleHttpClient;

// Generators
import org.apereo.cas.util.gen.RandomStringGenerator;
import org.apereo.cas.util.gen.DefaultRandomStringGenerator;

// Spring integration
import org.apereo.cas.util.spring.ApplicationContextProvider;

// JWT utilities
import org.apereo.cas.util.jwt.JsonWebTokenSigner;
import org.apereo.cas.util.jwt.JsonWebTokenEncryptor;

import org.apereo.cas.util.CollectionUtils;
import java.util.*;

// Create maps easily
Map<String, Object> attributes = CollectionUtils.wrap("key1", "value1", "key2", "value2");

// Convert to multi-valued map
Map<String, List<Object>> multiValued = CollectionUtils.toMultiValuedMap(attributes);

// Filter by distinct keys
List<User> uniqueUsers = users.stream()
    .filter(CollectionUtils.distinctByKey(User::getEmail))
    .collect(Collectors.toList());

import org.apereo.cas.util.DateTimeUtils;
import java.time.*;

// Parse various date formats
LocalDateTime dateTime = DateTimeUtils.localDateTimeOf("2024-01-15T10:30:00");
ZonedDateTime zonedTime = DateTimeUtils.zonedDateTimeOf(System.currentTimeMillis());

// Convert time units
TimeUnit timeUnit = DateTimeUtils.toTimeUnit(ChronoUnit.HOURS);

import org.apereo.cas.util.function.FunctionUtils;

// Conditional operations
String result = FunctionUtils.doIfNotBlank(inputString, String::toUpperCase);

// Exception handling
String safeResult = FunctionUtils.doAndHandle(() -> riskyOperation(), 
                                           Exception.class, 
                                           ex -> "default");

// Retry operations
String retryResult = FunctionUtils.doAndRetry(() -> unreliableOperation(), 
                                            3, 
                                            1000);

// Collection utilities
Map<String, Object> map = CollectionUtils.wrap("user", "john", "role", "admin");
Optional<String> first = CollectionUtils.firstElement(collection, String.class);

// Date/time utilities  
ZonedDateTime now = DateTimeUtils.zonedDateTimeOf(System.currentTimeMillis());
LocalDate date = DateTimeUtils.localDateOf(timestamp);

// Functional programming with exception handling
String result = FunctionUtils.doAndHandle(() -> parseJson(input), 
                                        JsonException.class, 
                                        ex -> "{}");

// Abstract cipher executor
public class MyCipher extends AbstractCipherExecutor<String, String> {
    @Override
    public String encode(String value, Object[] parameters) {
        return encrypt(value);
    }
    
    @Override  
    public String decode(String value, Object[] parameters) {
        return decrypt(value);
    }
}

// Certificate operations
X509Certificate cert = CertUtils.readCertificate(certResource);
PublicKey publicKey = AbstractCipherExecutor.extractPublicKeyFromResource(keyPath);

// HTTP client usage
HttpClient client = new SimpleHttpClient();
HttpMessage message = new HttpMessage(new URL("https://api.example.com"), "POST");
message.setContentType("application/json");
message.setEntity("{\"key\":\"value\"}");

boolean success = client.sendMessageToEndPoint(message);
HttpMessage response = client.sendMessageToEndPoint(new URL("https://api.example.com"));

// Random string generation
RandomStringGenerator generator = new DefaultRandomStringGenerator();
String token = generator.getNewString(32);

// Numeric generation  
NumericGenerator numGen = new DefaultRandomNumberGenerator();
long id = numGen.getNextLong();

// Specialized generators
RandomStringGenerator base64Gen = new Base64RandomStringGenerator();
RandomStringGenerator hexGen = new HexRandomStringGenerator();

// Application context access
ApplicationContext ctx = ApplicationContextProvider.getApplicationContext();
Optional<MyBean> bean = ApplicationContextProvider.getBean("myBean", MyBean.class);

// Bean registration
ApplicationContextProvider.registerBeanIntoApplicationContext(ctx, myBean, "beanName");

// Configuration properties
Optional<CasConfigurationProperties> config = 
    ApplicationContextProvider.getCasConfigurationProperties();

// JWT signing
JsonWebTokenSigner signer = new JsonWebTokenSigner(secretKey, algorithm);
JwtClaims claims = new JwtClaims();
claims.setSubject("user123");
String jwt = signer.sign(claims);

// JWT encryption
JsonWebTokenEncryptor encryptor = new JsonWebTokenEncryptor(encryptionKey, keyAlgorithm);
String encryptedJwt = encryptor.encrypt(payload);

// Basic serialization
byte[] bytes = SerializationUtils.serialize(myObject);
MyObject restored = SerializationUtils.deserialize(bytes, MyObject.class);

// Encrypted serialization
byte[] encrypted = SerializationUtils.serializeAndEncodeObject(cipher, myObject);
MyObject decrypted = SerializationUtils.decodeAndDeserializeObject(cipher, encrypted, 
                                                                  MyObject.class);

// Message sanitization
MessageSanitizer sanitizer = new DefaultMessageSanitizer();
String clean = sanitizer.sanitize(userInput);

// Principal name transformation  
PrincipalNameTransformer transformer = new ConvertCasePrincipalNameTransformer();
String transformed = transformer.transform("UserName"); // returns "username"

// Conditional functions
Function<String, String> processor = FunctionUtils.doIf(
    StringUtils::isNotBlank,
    String::toUpperCase,
    s -> "DEFAULT"
);

// Exception handling with retry
String result = FunctionUtils.doAndRetry(() -> {
    return callExternalService();
}, 3, 1000, IOException.class);

// Null-safe operations
FunctionUtils.doIfNotNull(user, u -> updateLastLogin(u));

// File watching
WatcherService watcher = new FileWatcherService();
watcher.start("config", path -> reloadConfiguration());

// Cache management
DistributedCacheManager<String, Object> cache = new MyDistributedCacheManager();
cache.set("key", value, Duration.ofMinutes(30));

// Virtual threading (Java 21+)
VirtualThreadDelegate delegate = new VirtualThreadDelegate();
ThreadFactory factory = delegate.virtualThreadFactory("cas-");
Thread vThread = delegate.newVirtualThread("worker", task);