Utilities

/**
 * Utility class providing convenient static methods for accessing common security operations.
 */
public abstract class SecurityUtils {
    /**
     * Returns the currently executing Subject associated with the calling thread, or a new empty/anonymous Subject if none is associated.
     * @return the Subject associated with the calling thread or a new empty/anonymous Subject if none is associated
     */
    public static Subject getSubject();

    /**
     * Returns the SecurityManager accessible to the calling code.
     * @return the SecurityManager accessible to the calling code
     */
    public static SecurityManager getSecurityManager();

    /**
     * Sets the SecurityManager accessible to all threads.
     * @param securityManager the SecurityManager to set
     */
    public static void setSecurityManager(SecurityManager securityManager);
}

// Get current user
Subject currentUser = SecurityUtils.getSubject();

// Check if user is authenticated
if (currentUser.isAuthenticated()) {
    System.out.println("User is logged in");
}

// Get security manager
SecurityManager sm = SecurityUtils.getSecurityManager();

// Set security manager (typically done during application startup)
DefaultSecurityManager securityManager = new DefaultSecurityManager(realm);
SecurityUtils.setSecurityManager(securityManager);

/**
 * Utility class for managing security context in thread-local storage.
 */
public final class ThreadContext {
    /**
     * Returns the SecurityManager bound to the current thread, or null if none is bound.
     * @return the SecurityManager bound to the current thread, or null if none is bound
     */
    public static SecurityManager getSecurityManager();

    /**
     * Binds a SecurityManager to the current thread.
     * @param securityManager the SecurityManager to bind to the current thread
     */
    public static void bind(SecurityManager securityManager);

    /**
     * Unbinds the SecurityManager from the current thread.
     * @return the SecurityManager previously bound to the current thread, or null if none was bound
     */
    public static SecurityManager unbindSecurityManager();

    /**
     * Returns the Subject bound to the current thread, or null if none is bound.
     * @return the Subject bound to the current thread, or null if none is bound
     */
    public static Subject getSubject();

    /**
     * Binds a Subject to the current thread.
     * @param subject the Subject to bind to the current thread
     */
    public static void bind(Subject subject);

    /**
     * Unbinds the Subject from the current thread.
     * @return the Subject previously bound to the current thread, or null if none was bound
     */
    public static Subject unbindSubject();

    /**
     * Returns all resources bound to the current thread.
     * @return all resources bound to the current thread as a Map
     */
    public static Map<Object, Object> getResources();

    /**
     * Returns the resource bound to the current thread under the specified key.
     * @param key the key used to lookup the resource
     * @return the resource bound to the current thread under the specified key
     */
    public static Object get(Object key);

    /**
     * Binds a resource to the current thread under the specified key.
     * @param key the key to bind the resource under
     * @param value the resource to bind
     */
    public static void put(Object key, Object value);

    /**
     * Unbinds the resource associated with the specified key from the current thread.
     * @param key the key of the resource to unbind
     * @return the resource that was unbound, or null if no resource was bound under that key
     */
    public static Object remove(Object key);

    /**
     * Removes all resources bound to the current thread.
     */
    public static void clear();
}

// Manual thread context management
public void executeInSecurityContext(Runnable task) {
    Subject subject = SecurityUtils.getSubject();
    
    try {
        // Bind current subject to new thread
        ThreadContext.bind(subject);
        
        // Execute task with security context
        task.run();
        
    } finally {
        // Always clean up thread context
        ThreadContext.clear();
    }
}

// Custom resource binding
ThreadContext.put("customKey", customObject);
Object retrieved = ThreadContext.get("customKey");
ThreadContext.remove("customKey");

/**
 * Interface for managing thread state that can be backed up and restored.
 */
public interface ThreadState {
    /**
     * Saves the current thread state and replaces it with the state represented by this instance.
     */
    void bind();

    /**
     * Completely removes the state that was previously bound.
     */
    void clear();

    /**
     * Restores the original thread state that existed before this instance's state was bound.
     */
    void restore();
}

/**
 * ThreadState implementation that manages Subject state for the current thread.
 */
public class SubjectThreadState implements ThreadState {
    /**
     * Constructor accepting the Subject that should be bound to the current thread.
     * @param subject the Subject that should be bound to the current thread
     */
    public SubjectThreadState(Subject subject);

    /**
     * Returns the Subject that will be bound to the current thread.
     * @return the Subject that will be bound to the current thread
     */
    public Subject getSubject();

    public void bind();
    public void clear();
    public void restore();
}

// Subject-aware thread execution
public void executeAsSubject(Subject subject, Runnable task) {
    SubjectThreadState threadState = new SubjectThreadState(subject);
    
    try {
        threadState.bind();
        task.run();
    } finally {
        threadState.restore();
    }
}

// Custom thread state implementation
public class CustomThreadState implements ThreadState {
    private final Map<String, Object> customState;
    private Map<Object, Object> originalResources;
    
    public CustomThreadState(Map<String, Object> state) {
        this.customState = state;
    }
    
    @Override
    public void bind() {
        originalResources = ThreadContext.getResources();
        customState.forEach(ThreadContext::put);
    }
    
    @Override
    public void restore() {
        ThreadContext.clear();
        if (originalResources != null) {
            originalResources.forEach(ThreadContext::put);
        }
    }
    
    @Override
    public void clear() {
        ThreadContext.clear();
    }
}

/**
 * Interface implemented by components that need initialization.
 */
public interface Initializable {
    /**
     * Initializes this instance after all properties have been set.
     * @throws ShiroException if initialization fails
     */
    void init() throws ShiroException;
}

/**
 * Interface implemented by components that need cleanup when destroyed.
 */
public interface Destroyable {
    /**
     * Destroys this instance, releasing any resources.
     * @throws Exception if destruction fails
     */
    void destroy() throws Exception;
}

/**
 * Interface implemented by components that have names.
 */
public interface Nameable {
    /**
     * Sets the name of this component.
     * @param name the name to assign to this component
     */
    void setName(String name);

    /**
     * Returns the name assigned to this component.
     * @return the name assigned to this component
     */
    String getName();
}

/**
 * Utility class for managing component lifecycles.
 */
public final class LifecycleUtils {
    /**
     * Initializes the specified object if it implements Initializable.
     * @param o the object to initialize
     * @throws ShiroException if initialization fails
     */
    public static void init(Object o) throws ShiroException;

    /**
     * Initializes all objects in the specified collection.
     * @param c the collection of objects to initialize
     * @throws ShiroException if initialization of any object fails
     */
    public static void init(Collection c) throws ShiroException;

    /**
     * Destroys the specified object if it implements Destroyable.
     * @param o the object to destroy
     */
    public static void destroy(Object o);

    /**
     * Destroys all objects in the specified collection.
     * @param c the collection of objects to destroy
     */
    public static void destroy(Collection c);
}

// Custom component with lifecycle
public class MySecurityComponent implements Initializable, Destroyable, Nameable {
    private String name;
    private boolean initialized = false;
    
    @Override
    public void init() throws ShiroException {
        if (initialized) {
            return;
        }
        
        // Perform initialization
        setupResources();
        validateConfiguration();
        initialized = true;
        
        System.out.println("Component " + name + " initialized");
    }
    
    @Override
    public void destroy() throws Exception {
        if (!initialized) {
            return;
        }
        
        // Cleanup resources
        releaseResources();
        initialized = false;
        
        System.out.println("Component " + name + " destroyed");
    }
    
    @Override
    public void setName(String name) {
        this.name = name;
    }
    
    @Override
    public String getName() {
        return name;
    }
    
    private void setupResources() {
        // Setup component resources
    }
    
    private void releaseResources() {
        // Release component resources
    }
    
    private void validateConfiguration() throws ShiroException {
        // Validate component configuration
        if (name == null) {
            throw new ShiroException("Component name must be specified");
        }
    }
}

// Using lifecycle utilities
List<Object> components = Arrays.asList(
    new MySecurityComponent(),
    new AnotherComponent(),
    new YetAnotherComponent()
);

// Initialize all components
LifecycleUtils.init(components);

// Later, destroy all components
LifecycleUtils.destroy(components);

/**
 * Generic factory interface for creating instances of type T.
 * @param <T> the type of object created by this factory
 */
public interface Factory<T> {
    /**
     * Creates and returns a new instance of type T.
     * @return a new instance of type T
     */
    T getInstance();
}

// Custom realm factory
public class DatabaseRealmFactory implements Factory<Realm> {
    private DataSource dataSource;
    
    public DatabaseRealmFactory(DataSource dataSource) {
        this.dataSource = dataSource;
    }
    
    @Override
    public Realm getInstance() {
        JdbcRealm realm = new JdbcRealm();
        realm.setDataSource(dataSource);
        realm.setAuthenticationQuery("SELECT password FROM users WHERE username = ?");
        realm.setUserRolesQuery("SELECT role FROM user_roles WHERE username = ?");
        return realm;
    }
}

// Security manager factory
public class SecurityManagerFactory implements Factory<SecurityManager> {
    private final Collection<Realm> realms;
    private final CacheManager cacheManager;
    
    public SecurityManagerFactory(Collection<Realm> realms, CacheManager cacheManager) {
        this.realms = realms;
        this.cacheManager = cacheManager;
    }
    
    @Override
    public SecurityManager getInstance() {
        DefaultSecurityManager sm = new DefaultSecurityManager();
        sm.setRealms(realms);
        sm.setCacheManager(cacheManager);
        return sm;
    }
}

// Usage
Factory<Realm> realmFactory = new DatabaseRealmFactory(dataSource);
Realm realm = realmFactory.getInstance();

Factory<SecurityManager> smFactory = new SecurityManagerFactory(
    Collections.singletonList(realm), 
    cacheManager
);
SecurityManager securityManager = smFactory.getInstance();

/**
 * String manipulation utilities commonly used throughout Shiro.
 */
public final class StringUtils {
    /**
     * Returns true if the specified string is null or empty.
     * @param str the string to check
     * @return true if the string is null or empty, false otherwise
     */
    public static boolean isEmpty(String str);

    /**
     * Returns true if the specified string has text (not null and not empty after trimming).
     * @param str the string to check
     * @return true if the string has text, false otherwise
     */
    public static boolean hasText(String str);

    /**
     * Returns true if the specified string has length (not null and length > 0).
     * @param str the string to check
     * @return true if the string has length, false otherwise
     */
    public static boolean hasLength(String str);

    /**
     * Cleans the specified string by removing leading and trailing whitespace.
     * @param str the string to clean
     * @return the cleaned string, or null if the input was null
     */
    public static String clean(String str);

    /**
     * Splits the specified string using the specified delimiter.
     * @param line the string to split
     * @param delimiter the delimiter to use for splitting
     * @return an array of tokens, or null if the input was null or empty
     */
    public static String[] split(String line, String delimiter);

    /**
     * Tokenizes the specified string using the specified delimiters.
     * @param str the string to tokenize
     * @param delimiters the delimiters to use
     * @return a list of tokens
     */
    public static List<String> tokenizeToStringList(String str, String delimiters);
}

/**
 * Collection manipulation utilities commonly used throughout Shiro.
 */
public final class CollectionUtils {
    /**
     * Returns true if the specified collection is null or empty.
     * @param c the collection to check
     * @return true if the collection is null or empty, false otherwise
     */
    public static boolean isEmpty(Collection c);

    /**
     * Returns the size of the specified collection, or 0 if null.
     * @param c the collection
     * @return the size of the collection, or 0 if null
     */
    public static int size(Collection c);

    /**
     * Returns true if the specified map is null or empty.
     * @param m the map to check
     * @return true if the map is null or empty, false otherwise
     */
    public static boolean isEmpty(Map m);

    /**
     * Returns the size of the specified map, or 0 if null.
     * @param m the map
     * @return the size of the map, or 0 if null
     */
    public static int size(Map m);

    /**
     * Converts the specified collection to a set.
     * @param c the collection to convert
     * @return a set containing the collection's elements
     */
    public static Set asSet(Collection c);
}

// String utilities
String username = "  john.doe  ";
if (StringUtils.hasText(username)) {
    username = StringUtils.clean(username);  // "john.doe"
}

String roles = "admin,user,guest";
String[] roleArray = StringUtils.split(roles, ",");  // ["admin", "user", "guest"]

List<String> roleList = StringUtils.tokenizeToStringList(roles, ",");

// Collection utilities
Collection<String> permissions = getPermissions();
if (!CollectionUtils.isEmpty(permissions)) {
    System.out.println("User has " + CollectionUtils.size(permissions) + " permissions");
}

Set<String> uniqueRoles = CollectionUtils.asSet(roleList);

/**
 * Class loading and reflection utilities.
 */
public final class ClassUtils {
    /**
     * Returns the thread context class loader, or the system class loader if the context loader is null.
     * @return the thread context class loader, or the system class loader if the context loader is null
     */
    public static ClassLoader getDefaultClassLoader();

    /**
     * Loads the class with the specified name using the default class loader.
     * @param className the name of the class to load
     * @return the loaded class
     * @throws ClassNotFoundException if the class cannot be found
     */
    public static Class forName(String className) throws ClassNotFoundException;

    /**
     * Loads the class with the specified name using the specified class loader.
     * @param className the name of the class to load
     * @param classLoader the class loader to use
     * @return the loaded class
     * @throws ClassNotFoundException if the class cannot be found
     */
    public static Class forName(String className, ClassLoader classLoader) throws ClassNotFoundException;

    /**
     * Instantiates the class with the specified name using its default constructor.
     * @param className the name of the class to instantiate
     * @return a new instance of the specified class
     * @throws InstantiationException if the class cannot be instantiated
     * @throws IllegalAccessException if the constructor is not accessible
     * @throws ClassNotFoundException if the class cannot be found
     */
    public static Object newInstance(String className) throws InstantiationException, IllegalAccessException, ClassNotFoundException;

    /**
     * Instantiates the specified class using its default constructor.
     * @param clazz the class to instantiate
     * @return a new instance of the specified class
     * @throws InstantiationException if the class cannot be instantiated
     * @throws IllegalAccessException if the constructor is not accessible
     */
    public static Object newInstance(Class clazz) throws InstantiationException, IllegalAccessException;

    /**
     * Returns true if the specified class is available in the classpath.
     * @param className the name of the class to check
     * @return true if the class is available, false otherwise
     */
    public static boolean isAvailable(String className);
}

// Dynamic class loading
if (ClassUtils.isAvailable("com.company.CustomRealm")) {
    try {
        Class<?> realmClass = ClassUtils.forName("com.company.CustomRealm");
        Realm customRealm = (Realm) ClassUtils.newInstance(realmClass);
        
        // Use the dynamically loaded realm
        securityManager.setRealm(customRealm);
        
    } catch (Exception e) {
        System.err.println("Failed to load custom realm: " + e.getMessage());
    }
}

// Get default class loader
ClassLoader classLoader = ClassUtils.getDefaultClassLoader();

// Load class with specific class loader
Class<?> myClass = ClassUtils.forName("com.example.MyClass", classLoader);
Object instance = ClassUtils.newInstance(myClass);

/**
 * Executor that automatically associates Subject instances with executing threads.
 */
public class SubjectAwareExecutor implements Executor {
    /**
     * Constructor accepting the target Executor that will actually execute the commands.
     * @param targetExecutor the target Executor that will actually execute the commands
     */
    public SubjectAwareExecutor(Executor targetExecutor);

    /**
     * Executes the specified command with the current Subject automatically associated with the executing thread.
     * @param command the command to execute
     */
    public void execute(Runnable command);
}

/**
 * ExecutorService that automatically associates Subject instances with executing threads.
 */
public class SubjectAwareExecutorService extends AbstractExecutorService {
    /**
     * Constructor accepting the target ExecutorService that will actually execute the commands.
     * @param targetExecutorService the target ExecutorService that will actually execute the commands
     */
    public SubjectAwareExecutorService(ExecutorService targetExecutorService);

    /**
     * Returns the target ExecutorService that actually executes the commands.
     * @return the target ExecutorService that actually executes the commands
     */
    public ExecutorService getTargetExecutorService();

    public void execute(Runnable command);
    public <T> Future<T> submit(Callable<T> task);
    public <T> Future<T> submit(Runnable task, T result);
    public Future<?> submit(Runnable task);
}

// Subject-aware executor
Subject currentUser = SecurityUtils.getSubject();
Executor standardExecutor = Executors.newFixedThreadPool(10);
SubjectAwareExecutor subjectAwareExecutor = new SubjectAwareExecutor(standardExecutor);

// Execute task with subject context
subjectAwareExecutor.execute(() -> {
    // This code runs with the current user's security context
    Subject subject = SecurityUtils.getSubject();
    if (subject.hasRole("admin")) {
        performAdminTask();
    }
});

// Subject-aware executor service
ExecutorService standardService = Executors.newCachedThreadPool();
SubjectAwareExecutorService subjectAwareService = new SubjectAwareExecutorService(standardService);

// Submit callable with subject context
Future<String> result = subjectAwareService.submit(() -> {
    Subject subject = SecurityUtils.getSubject();
    return "Task completed by user: " + subject.getPrincipal();
});

try {
    String message = result.get();
    System.out.println(message);
} catch (Exception e) {
    e.printStackTrace();
}

/**
 * Interface implemented by components that can be configured with a CacheManager.
 */
public interface CacheManagerAware {
    /**
     * Sets the CacheManager that should be used for caching.
     * @param cacheManager the CacheManager to use for caching
     */
    void setCacheManager(CacheManager cacheManager);
}