/*
 * Copyright 2002-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.util;

import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

/**
 * Miscellaneous class utility methods. Mainly for internal use within the framework; consider <a
 * href="http://commons.apache.org/lang/" target="_blank">Apache Commons Lang</a> for a more comprehensive suite of
 * class utilities.
 * 
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rob Harrop
 * @author Sam Brannen
 * @author Roy Clarkson
 * @since 1.0
 * @see TypeUtils
 * @see ReflectionUtils
 */
@SuppressWarnings("unchecked")
public abstract class ClassUtils {

	/** Suffix for array class names: "[]" */
	public static final String ARRAY_SUFFIX = "[]";

	/** Prefix for internal array class names: "[" */
	private static final String INTERNAL_ARRAY_PREFIX = "[";

	/** Prefix for internal non-primitive array class names: "[L" */
	private static final String NON_PRIMITIVE_ARRAY_PREFIX = "[L";

	/** The package separator character '.' */
	private static final char PACKAGE_SEPARATOR = '.';

	/** The inner class separator character '$' */
	private static final char INNER_CLASS_SEPARATOR = '$';

	/** The CGLIB class separator character "$$" */
	public static final String CGLIB_CLASS_SEPARATOR = "$$";

	/** The ".class" file suffix */
	public static final String CLASS_FILE_SUFFIX = ".class";


	/**
	 * Map with primitive wrapper type as key and corresponding primitive type as value, for example: Integer.class ->
	 * int.class.
	 */
	private static final Map<Class<?>, Class<?>> primitiveWrapperTypeMap = new HashMap<Class<?>, Class<?>>(8);

	/**
	 * Map with primitive type as key and corresponding wrapper type as value, for example: int.class -> Integer.class.
	 */
	private static final Map<Class<?>, Class<?>> primitiveTypeToWrapperMap = new HashMap<Class<?>, Class<?>>(8);

	/**
	 * Map with primitive type name as key and corresponding primitive type as value, for example: "int" -> "int.class".
	 */
	private static final Map<String, Class<?>> primitiveTypeNameMap = new HashMap<String, Class<?>>(32);

	/**
	 * Map with common "java.lang" class name as key and corresponding Class as value. Primarily for efficient
	 * deserialization of remote invocations.
	 */
	private static final Map<String, Class<?>> commonClassCache = new HashMap<String, Class<?>>(32);


	static {
		primitiveWrapperTypeMap.put(Boolean.class, boolean.class);
		primitiveWrapperTypeMap.put(Byte.class, byte.class);
		primitiveWrapperTypeMap.put(Character.class, char.class);
		primitiveWrapperTypeMap.put(Double.class, double.class);
		primitiveWrapperTypeMap.put(Float.class, float.class);
		primitiveWrapperTypeMap.put(Integer.class, int.class);
		primitiveWrapperTypeMap.put(Long.class, long.class);
		primitiveWrapperTypeMap.put(Short.class, short.class);

		for (Map.Entry<Class<?>, Class<?>> entry : primitiveWrapperTypeMap.entrySet()) {
			primitiveTypeToWrapperMap.put(entry.getValue(), entry.getKey());
			registerCommonClasses(entry.getKey());
		}

		Set<Class<?>> primitiveTypes = new HashSet<Class<?>>(32);
		primitiveTypes.addAll(primitiveWrapperTypeMap.values());
		primitiveTypes.addAll(Arrays.asList(boolean[].class, byte[].class, char[].class, double[].class, float[].class, int[].class, long[].class, short[].class));
		primitiveTypes.add(void.class);
		for (Class<?> primitiveType : primitiveTypes) {
			primitiveTypeNameMap.put(primitiveType.getName(), primitiveType);
		}

		registerCommonClasses(Boolean[].class, Byte[].class, Character[].class, Double[].class, Float[].class, Integer[].class, Long[].class, Short[].class);
		registerCommonClasses(Number.class, Number[].class, String.class, String[].class, Object.class, Object[].class, Class.class, Class[].class);
		registerCommonClasses(Throwable.class, Exception.class, RuntimeException.class, Error.class, StackTraceElement.class, StackTraceElement[].class);
	}


	/**
	 * Register the given common classes with the ClassUtils cache.
	 */
	private static void registerCommonClasses(Class<?>... commonClasses) {
		for (Class<?> clazz : commonClasses) {
			commonClassCache.put(clazz.getName(), clazz);
		}
	}

	/**
	 * Return the default ClassLoader to use: typically the thread context ClassLoader, if available; the ClassLoader
	 * that loaded the ClassUtils class will be used as fallback.
	 * <p>
	 * Call this method if you intend to use the thread context ClassLoader in a scenario where you absolutely need a
	 * non-null ClassLoader reference: for example, for class path resource loading (but not necessarily for
	 * <code>Class.forName</code>, which accepts a <code>null</code> ClassLoader reference as well).
	 * @return the default ClassLoader (never <code>null</code>)
	 * @see java.lang.Thread#getContextClassLoader()
	 */
	public static ClassLoader getDefaultClassLoader() {
		ClassLoader cl = null;
		try {
			cl = Thread.currentThread().getContextClassLoader();
		} catch (Throwable ex) {
			// Cannot access thread context ClassLoader - falling back to system class loader...
		}
		if (cl == null) {
			// No thread context class loader -> use class loader of this class.
			cl = ClassUtils.class.getClassLoader();
		}
		return cl;
	}

	/**
	 * Override the thread context ClassLoader with the environment's bean ClassLoader if necessary, i.e. if the bean
	 * ClassLoader is not equivalent to the thread context ClassLoader already.
	 * @param classLoaderToUse the actual ClassLoader to use for the thread context
	 * @return the original thread context ClassLoader, or <code>null</code> if not overridden
	 */
	public static ClassLoader overrideThreadContextClassLoader(ClassLoader classLoaderToUse) {
		Thread currentThread = Thread.currentThread();
		ClassLoader threadContextClassLoader = currentThread.getContextClassLoader();
		if (classLoaderToUse != null && !classLoaderToUse.equals(threadContextClassLoader)) {
			currentThread.setContextClassLoader(classLoaderToUse);
			return threadContextClassLoader;
		} else {
			return null;
		}
	}

	/**
	 * Replacement for <code>Class.forName()</code> that also returns Class instances for primitives (like "int") and
	 * array class names (like "String[]").
	 * <p>
	 * Always uses the default class loader: that is, preferably the thread context class loader, or the ClassLoader
	 * that loaded the ClassUtils class as fallback.
	 * @param name the name of the Class
	 * @return Class instance for the supplied name
	 * @throws ClassNotFoundException if the class was not found
	 * @throws LinkageError if the class file could not be loaded
	 * @see Class#forName(String, boolean, ClassLoader)
	 * @see #getDefaultClassLoader()
	 * @deprecated as of Spring 3.0, in favor of specifying a ClassLoader explicitly: see
	 *             {@link #forName(String, ClassLoader)}
	 */
	@Deprecated
	public static Class<?> forName(String name) throws ClassNotFoundException, LinkageError {
		return forName(name, getDefaultClassLoader());
	}

	/**
	 * Replacement for <code>Class.forName()</code> that also returns Class instances for primitives (e.g."int") and
	 * array class names (e.g. "String[]"). Furthermore, it is also capable of resolving inner class names in Java
	 * source style (e.g. "java.lang.Thread.State" instead of "java.lang.Thread$State").
	 * @param name the name of the Class
	 * @param classLoader the class loader to use (may be <code>null</code>, which indicates the default class loader)
	 * @return Class instance for the supplied name
	 * @throws ClassNotFoundException if the class was not found
	 * @throws LinkageError if the class file could not be loaded
	 * @see Class#forName(String, boolean, ClassLoader)
	 */
	public static Class<?> forName(String name, ClassLoader classLoader) throws ClassNotFoundException, LinkageError {
		Assert.notNull(name, "Name must not be null");

		Class<?> clazz = resolvePrimitiveClassName(name);
		if (clazz == null) {
			clazz = commonClassCache.get(name);
		}
		if (clazz != null) {
			return clazz;
		}

		// "java.lang.String[]" style arrays
		if (name.endsWith(ARRAY_SUFFIX)) {
			String elementClassName = name.substring(0, name.length() - ARRAY_SUFFIX.length());
			Class<?> elementClass = forName(elementClassName, classLoader);
			return Array.newInstance(elementClass, 0).getClass();
		}

		// "[Ljava.lang.String;" style arrays
		if (name.startsWith(NON_PRIMITIVE_ARRAY_PREFIX) && name.endsWith(";")) {
			String elementName = name.substring(NON_PRIMITIVE_ARRAY_PREFIX.length(), name.length() - 1);
			Class<?> elementClass = forName(elementName, classLoader);
			return Array.newInstance(elementClass, 0).getClass();
		}

		// "[[I" or "[[Ljava.lang.String;" style arrays
		if (name.startsWith(INTERNAL_ARRAY_PREFIX)) {
			String elementName = name.substring(INTERNAL_ARRAY_PREFIX.length());
			Class<?> elementClass = forName(elementName, classLoader);
			return Array.newInstance(elementClass, 0).getClass();
		}

		ClassLoader classLoaderToUse = classLoader;
		if (classLoaderToUse == null) {
			classLoaderToUse = getDefaultClassLoader();
		}
		try {
			return classLoaderToUse.loadClass(name);
		} catch (ClassNotFoundException ex) {
			int lastDotIndex = name.lastIndexOf('.');
			if (lastDotIndex != -1) {
				String innerClassName = name.substring(0, lastDotIndex) + '$' + name.substring(lastDotIndex + 1);
				try {
					return classLoaderToUse.loadClass(innerClassName);
				} catch (ClassNotFoundException ex2) {
					// swallow - let original exception get through
				}
			}
			throw ex;
		}
	}

	/**
	 * Resolve the given class name into a Class instance. Supports primitives (like "int") and array class names (like
	 * "String[]").
	 * <p>
	 * This is effectively equivalent to the <code>forName</code> method with the same arguments, with the only
	 * difference being the exceptions thrown in case of class loading failure.
	 * @param className the name of the Class
	 * @param classLoader the class loader to use (may be <code>null</code>, which indicates the default class loader)
	 * @return Class instance for the supplied name
	 * @throws IllegalArgumentException if the class name was not resolvable (that is, the class could not be found or
	 *             the class file could not be loaded)
	 * @see #forName(String, ClassLoader)
	 */
	public static Class<?> resolveClassName(String className, ClassLoader classLoader) throws IllegalArgumentException {
		try {
			return forName(className, classLoader);
		} catch (ClassNotFoundException ex) {
			throw new IllegalArgumentException("Cannot find class [" + className + "]", ex);
		} catch (LinkageError ex) {
			throw new IllegalArgumentException("Error loading class [" + className + "]: problem with class file or dependent class.", ex);
		}
	}

	/**
	 * Resolve the given class name as primitive class, if appropriate, according to the JVM's naming rules for
	 * primitive classes.
	 * <p>
	 * Also supports the JVM's internal class names for primitive arrays. Does <i>not</i> support the "[]" suffix
	 * notation for primitive arrays; this is only supported by {@link #forName(String, ClassLoader)}.
	 * @param name the name of the potentially primitive class
	 * @return the primitive class, or <code>null</code> if the name does not denote a primitive class or primitive
	 *         array class
	 */
	public static Class<?> resolvePrimitiveClassName(String name) {
		Class<?> result = null;
		// Most class names will be quite long, considering that they
		// SHOULD sit in a package, so a length check is worthwhile.
		if (name != null && name.length() <= 8) {
			// Could be a primitive - likely.
			result = primitiveTypeNameMap.get(name);
		}
		return result;
	}

	/**
	 * Determine whether the {@link Class} identified by the supplied name is present and can be loaded. Will return
	 * <code>false</code> if either the class or one of its dependencies is not present or cannot be loaded.
	 * @param className the name of the class to check
	 * @return whether the specified class is present
	 * @deprecated as of Spring 2.5, in favor of {@link #isPresent(String, ClassLoader)}
	 */
	@Deprecated
	public static boolean isPresent(String className) {
		return isPresent(className, getDefaultClassLoader());
	}

	/**
	 * Determine whether the {@link Class} identified by the supplied name is present and can be loaded. Will return
	 * <code>false</code> if either the class or one of its dependencies is not present or cannot be loaded.
	 * @param className the name of the class to check
	 * @param classLoader the class loader to use (may be <code>null</code>, which indicates the default class loader)
	 * @return whether the specified class is present
	 */
	public static boolean isPresent(String className, ClassLoader classLoader) {
		try {
			forName(className, classLoader);
			return true;
		} catch (Throwable ex) {
			// Class or one of its dependencies is not present...
			return false;
		}
	}

	/**
	 * Return the user-defined class for the given instance: usually simply the class of the given instance, but the
	 * original class in case of a CGLIB-generated subclass.
	 * @param instance the instance to check
	 * @return the user-defined class
	 */
	public static Class<?> getUserClass(Object instance) {
		Assert.notNull(instance, "Instance must not be null");
		return getUserClass(instance.getClass());
	}

	/**
	 * Return the user-defined class for the given class: usually simply the given class, but the original class in case
	 * of a CGLIB-generated subclass.
	 * @param clazz the class to check
	 * @return the user-defined class
	 */
	public static Class<?> getUserClass(Class<?> clazz) {
		if (clazz != null && clazz.getName().contains(CGLIB_CLASS_SEPARATOR)) {
			Class<?> superClass = clazz.getSuperclass();
			if (superClass != null && !Object.class.equals(superClass)) {
				return superClass;
			}
		}
		return clazz;
	}

	/**
	 * Check whether the given class is cache-safe in the given context, i.e. whether it is loaded by the given
	 * ClassLoader or a parent of it.
	 * @param clazz the class to analyze
	 * @param classLoader the ClassLoader to potentially cache metadata in
	 */
	public static boolean isCacheSafe(Class<?> clazz, ClassLoader classLoader) {
		Assert.notNull(clazz, "Class must not be null");
		ClassLoader target = clazz.getClassLoader();
		if (target == null) {
			return false;
		}
		ClassLoader cur = classLoader;
		if (cur == target) {
			return true;
		}
		while (cur != null) {
			cur = cur.getParent();
			if (cur == target) {
				return true;
			}
		}
		return false;
	}


	/**
	 * Get the class name without the qualified package name.
	 * @param className the className to get the short name for
	 * @return the class name of the class without the package name
	 * @throws IllegalArgumentException if the className is empty
	 */
	public static String getShortName(String className) {
		Assert.hasLength(className, "Class name must not be empty");
		int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR);
		int nameEndIndex = className.indexOf(CGLIB_CLASS_SEPARATOR);
		if (nameEndIndex == -1) {
			nameEndIndex = className.length();
		}
		String shortName = className.substring(lastDotIndex + 1, nameEndIndex);
		shortName = shortName.replace(INNER_CLASS_SEPARATOR, PACKAGE_SEPARATOR);
		return shortName;
	}

	/**
	 * Get the class name without the qualified package name.
	 * @param clazz the class to get the short name for
	 * @return the class name of the class without the package name
	 */
	public static String getShortName(Class<?> clazz) {
		return getShortName(getQualifiedName(clazz));
	}

	/**
	 * Determine the name of the class file, relative to the containing package: e.g. "String.class"
	 * @param clazz the class
	 * @return the file name of the ".class" file
	 */
	public static String getClassFileName(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		String className = clazz.getName();
		int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR);
		return className.substring(lastDotIndex + 1) + CLASS_FILE_SUFFIX;
	}

	/**
	 * Determine the name of the package of the given class: e.g. "java.lang" for the <code>java.lang.String</code>
	 * class.
	 * @param clazz the class
	 * @return the package name, or the empty String if the class is defined in the default package
	 */
	public static String getPackageName(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		String className = clazz.getName();
		int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR);
		return (lastDotIndex != -1 ? className.substring(0, lastDotIndex) : "");
	}

	/**
	 * Return the qualified name of the given class: usually simply the class name, but component type class name + "[]"
	 * for arrays.
	 * @param clazz the class
	 * @return the qualified name of the class
	 */
	public static String getQualifiedName(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		if (clazz.isArray()) {
			return getQualifiedNameForArray(clazz);
		} else {
			return clazz.getName();
		}
	}

	/**
	 * Build a nice qualified name for an array: component type class name + "[]".
	 * @param clazz the array class
	 * @return a qualified name for the array class
	 */
	private static String getQualifiedNameForArray(Class<?> clazz) {
		StringBuilder result = new StringBuilder();
		while (clazz.isArray()) {
			clazz = clazz.getComponentType();
			result.append(ClassUtils.ARRAY_SUFFIX);
		}
		result.insert(0, clazz.getName());
		return result.toString();
	}

	/**
	 * Return the qualified name of the given method, consisting of fully qualified interface/class name + "." + method
	 * name.
	 * @param method the method
	 * @return the qualified name of the method
	 */
	public static String getQualifiedMethodName(Method method) {
		Assert.notNull(method, "Method must not be null");
		return method.getDeclaringClass().getName() + "." + method.getName();
	}

	/**
	 * Return a descriptive name for the given object's type: usually simply the class name, but component type class
	 * name + "[]" for arrays, and an appended list of implemented interfaces for JDK proxies.
	 * @param value the value to introspect
	 * @return the qualified name of the class
	 */
	public static String getDescriptiveType(Object value) {
		if (value == null) {
			return null;
		}
		Class<?> clazz = value.getClass();
		if (Proxy.isProxyClass(clazz)) {
			StringBuilder result = new StringBuilder(clazz.getName());
			result.append(" implementing ");
			Class<?>[] ifcs = clazz.getInterfaces();
			for (int i = 0; i < ifcs.length; i++) {
				result.append(ifcs[i].getName());
				if (i < ifcs.length - 1) {
					result.append(',');
				}
			}
			return result.toString();
		} else if (clazz.isArray()) {
			return getQualifiedNameForArray(clazz);
		} else {
			return clazz.getName();
		}
	}

	/**
	 * Check whether the given class matches the user-specified type name.
	 * @param clazz the class to check
	 * @param typeName the type name to match
	 */
	public static boolean matchesTypeName(Class<?> clazz, String typeName) {
		return (typeName != null && (typeName.equals(clazz.getName()) || typeName.equals(clazz.getSimpleName()) || (clazz.isArray() && typeName.equals(getQualifiedNameForArray(clazz)))));
	}


	/**
	 * Determine whether the given class has a public constructor with the given signature.
	 * <p>
	 * Essentially translates <code>NoSuchMethodException</code> to "false".
	 * @param clazz the clazz to analyze
	 * @param paramTypes the parameter types of the method
	 * @return whether the class has a corresponding constructor
	 * @see java.lang.Class#getMethod
	 */
	public static boolean hasConstructor(Class<?> clazz, Class<?>... paramTypes) {
		return (getConstructorIfAvailable(clazz, paramTypes) != null);
	}

	/**
	 * Determine whether the given class has a public constructor with the given signature, and return it if available
	 * (else return <code>null</code>).
	 * <p>
	 * Essentially translates <code>NoSuchMethodException</code> to <code>null</code>.
	 * @param clazz the clazz to analyze
	 * @param paramTypes the parameter types of the method
	 * @return the constructor, or <code>null</code> if not found
	 * @see java.lang.Class#getConstructor
	 */
	public static <T> Constructor<T> getConstructorIfAvailable(Class<T> clazz, Class<?>... paramTypes) {
		Assert.notNull(clazz, "Class must not be null");
		try {
			return clazz.getConstructor(paramTypes);
		} catch (NoSuchMethodException ex) {
			return null;
		}
	}

	/**
	 * Determine whether the given class has a method with the given signature.
	 * <p>
	 * Essentially translates <code>NoSuchMethodException</code> to "false".
	 * @param clazz the clazz to analyze
	 * @param methodName the name of the method
	 * @param paramTypes the parameter types of the method
	 * @return whether the class has a corresponding method
	 * @see java.lang.Class#getMethod
	 */
	public static boolean hasMethod(Class<?> clazz, String methodName, Class<?>... paramTypes) {
		return (getMethodIfAvailable(clazz, methodName, paramTypes) != null);
	}

	/**
	 * Determine whether the given class has a method with the given signature, and return it if available (else throws
	 * an <code>IllegalStateException</code>).
	 * <p>
	 * Essentially translates <code>NoSuchMethodException</code> to <code>IllegalStateException</code>.
	 * @param clazz the clazz to analyze
	 * @param methodName the name of the method
	 * @param paramTypes the parameter types of the method
	 * @return the method (never <code>null</code>)
	 * @throws IllegalStateException if the method has not been found
	 * @see java.lang.Class#getMethod
	 */
	public static Method getMethod(Class<?> clazz, String methodName, Class<?>... paramTypes) {
		Assert.notNull(clazz, "Class must not be null");
		Assert.notNull(methodName, "Method name must not be null");
		try {
			return clazz.getMethod(methodName, paramTypes);
		} catch (NoSuchMethodException ex) {
			throw new IllegalStateException("Expected method not found: " + ex);
		}
	}

	/**
	 * Determine whether the given class has a method with the given signature, and return it if available (else return
	 * <code>null</code>).
	 * <p>
	 * Essentially translates <code>NoSuchMethodException</code> to <code>null</code>.
	 * @param clazz the clazz to analyze
	 * @param methodName the name of the method
	 * @param paramTypes the parameter types of the method
	 * @return the method, or <code>null</code> if not found
	 * @see java.lang.Class#getMethod
	 */
	public static Method getMethodIfAvailable(Class<?> clazz, String methodName, Class<?>... paramTypes) {
		Assert.notNull(clazz, "Class must not be null");
		Assert.notNull(methodName, "Method name must not be null");
		try {
			return clazz.getMethod(methodName, paramTypes);
		} catch (NoSuchMethodException ex) {
			return null;
		}
	}

	/**
	 * Return the number of methods with a given name (with any argument types), for the given class and/or its
	 * superclasses. Includes non-public methods.
	 * @param clazz the clazz to check
	 * @param methodName the name of the method
	 * @return the number of methods with the given name
	 */
	public static int getMethodCountForName(Class<?> clazz, String methodName) {
		Assert.notNull(clazz, "Class must not be null");
		Assert.notNull(methodName, "Method name must not be null");
		int count = 0;
		Method[] declaredMethods = clazz.getDeclaredMethods();
		for (Method method : declaredMethods) {
			if (methodName.equals(method.getName())) {
				count++;
			}
		}
		Class<?>[] ifcs = clazz.getInterfaces();
		for (Class<?> ifc : ifcs) {
			count += getMethodCountForName(ifc, methodName);
		}
		if (clazz.getSuperclass() != null) {
			count += getMethodCountForName(clazz.getSuperclass(), methodName);
		}
		return count;
	}

	/**
	 * Does the given class or one of its superclasses at least have one or more methods with the supplied name (with
	 * any argument types)? Includes non-public methods.
	 * @param clazz the clazz to check
	 * @param methodName the name of the method
	 * @return whether there is at least one method with the given name
	 */
	public static boolean hasAtLeastOneMethodWithName(Class<?> clazz, String methodName) {
		Assert.notNull(clazz, "Class must not be null");
		Assert.notNull(methodName, "Method name must not be null");
		Method[] declaredMethods = clazz.getDeclaredMethods();
		for (Method method : declaredMethods) {
			if (method.getName().equals(methodName)) {
				return true;
			}
		}
		Class<?>[] ifcs = clazz.getInterfaces();
		for (Class<?> ifc : ifcs) {
			if (hasAtLeastOneMethodWithName(ifc, methodName)) {
				return true;
			}
		}
		return (clazz.getSuperclass() != null && hasAtLeastOneMethodWithName(clazz.getSuperclass(), methodName));
	}

	/**
	 * Return a public static method of a class.
	 * @param methodName the static method name
	 * @param clazz the class which defines the method
	 * @param args the parameter types to the method
	 * @return the static method, or <code>null</code> if no static method was found
	 * @throws IllegalArgumentException if the method name is blank or the clazz is null
	 */
	public static Method getStaticMethod(Class<?> clazz, String methodName, Class<?>... args) {
		Assert.notNull(clazz, "Class must not be null");
		Assert.notNull(methodName, "Method name must not be null");
		try {
			Method method = clazz.getMethod(methodName, args);
			return Modifier.isStatic(method.getModifiers()) ? method : null;
		} catch (NoSuchMethodException ex) {
			return null;
		}
	}

	/**
	 * Check if the given class represents a primitive wrapper, i.e. Boolean, Byte, Character, Short, Integer, Long,
	 * Float, or Double.
	 * @param clazz the class to check
	 * @return whether the given class is a primitive wrapper class
	 */
	public static boolean isPrimitiveWrapper(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		return primitiveWrapperTypeMap.containsKey(clazz);
	}

	/**
	 * Check if the given class represents a primitive (i.e. boolean, byte, char, short, int, long, float, or double) or
	 * a primitive wrapper (i.e. Boolean, Byte, Character, Short, Integer, Long, Float, or Double).
	 * @param clazz the class to check
	 * @return whether the given class is a primitive or primitive wrapper class
	 */
	public static boolean isPrimitiveOrWrapper(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		return (clazz.isPrimitive() || isPrimitiveWrapper(clazz));
	}

	/**
	 * Check if the given class represents an array of primitives, i.e. boolean, byte, char, short, int, long, float, or
	 * double.
	 * @param clazz the class to check
	 * @return whether the given class is a primitive array class
	 */
	public static boolean isPrimitiveArray(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		return (clazz.isArray() && clazz.getComponentType().isPrimitive());
	}

	/**
	 * Check if the given class represents an array of primitive wrappers, i.e. Boolean, Byte, Character, Short,
	 * Integer, Long, Float, or Double.
	 * @param clazz the class to check
	 * @return whether the given class is a primitive wrapper array class
	 */
	public static boolean isPrimitiveWrapperArray(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		return (clazz.isArray() && isPrimitiveWrapper(clazz.getComponentType()));
	}

	/**
	 * Resolve the given class if it is a primitive class, returning the corresponding primitive wrapper type instead.
	 * @param clazz the class to check
	 * @return the original class, or a primitive wrapper for the original primitive type
	 */
	public static Class<?> resolvePrimitiveIfNecessary(Class<?> clazz) {
		Assert.notNull(clazz, "Class must not be null");
		return (clazz.isPrimitive() && clazz != void.class ? primitiveTypeToWrapperMap.get(clazz) : clazz);
	}

	/**
	 * Check if the right-hand side type may be assigned to the left-hand side type, assuming setting by reflection.
	 * Considers primitive wrapper classes as assignable to the corresponding primitive types.
	 * @param lhsType the target type
	 * @param rhsType the value type that should be assigned to the target type
	 * @return if the target type is assignable from the value type
	 * @see TypeUtils#isAssignable
	 */
	@SuppressWarnings("rawtypes")
	public static boolean isAssignable(Class<?> lhsType, Class<?> rhsType) {
		Assert.notNull(lhsType, "Left-hand side type must not be null");
		Assert.notNull(rhsType, "Right-hand side type must not be null");
		if (lhsType.isAssignableFrom(rhsType)) {
			return true;
		}
		if (lhsType.isPrimitive()) {
			Class resolvedPrimitive = primitiveWrapperTypeMap.get(rhsType);
			if (resolvedPrimitive != null && lhsType.equals(resolvedPrimitive)) {
				return true;
			}
		} else {
			Class resolvedWrapper = primitiveTypeToWrapperMap.get(rhsType);
			if (resolvedWrapper != null && lhsType.isAssignableFrom(resolvedWrapper)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Determine if the given type is assignable from the given value, assuming setting by reflection. Considers
	 * primitive wrapper classes as assignable to the corresponding primitive types.
	 * @param type the target type
	 * @param value the value that should be assigned to the type
	 * @return if the type is assignable from the value
	 */
	public static boolean isAssignableValue(Class<?> type, Object value) {
		Assert.notNull(type, "Type must not be null");
		return (value != null ? isAssignable(type, value.getClass()) : !type.isPrimitive());
	}


	/**
	 * Convert a "/"-based resource path to a "."-based fully qualified class name.
	 * @param resourcePath the resource path pointing to a class
	 * @return the corresponding fully qualified class name
	 */
	public static String convertResourcePathToClassName(String resourcePath) {
		Assert.notNull(resourcePath, "Resource path must not be null");
		return resourcePath.replace('/', '.');
	}

	/**
	 * Convert a "."-based fully qualified class name to a "/"-based resource path.
	 * @param className the fully qualified class name
	 * @return the corresponding resource path, pointing to the class
	 */
	public static String convertClassNameToResourcePath(String className) {
		Assert.notNull(className, "Class name must not be null");
		return className.replace('.', '/');
	}

	/**
	 * Return a path suitable for use with <code>ClassLoader.getResource</code> (also suitable for use with
	 * <code>Class.getResource</code> by prepending a slash ('/') to the return value). Built by taking the package of
	 * the specified class file, converting all dots ('.') to slashes ('/'), adding a trailing slash if necessary, and
	 * concatenating the specified resource name to this. <br/>
	 * As such, this function may be used to build a path suitable for loading a resource file that is in the same
	 * package as a class file, although {@link org.springframework.core.io.ClassPathResource} is usually even more
	 * convenient.
	 * @param clazz the Class whose package will be used as the base
	 * @param resourceName the resource name to append. A leading slash is optional.
	 * @return the built-up resource path
	 * @see java.lang.ClassLoader#getResource
	 * @see java.lang.Class#getResource
	 */
	public static String addResourcePathToPackagePath(Class<?> clazz, String resourceName) {
		Assert.notNull(resourceName, "Resource name must not be null");
		if (!resourceName.startsWith("/")) {
			return classPackageAsResourcePath(clazz) + "/" + resourceName;
		}
		return classPackageAsResourcePath(clazz) + resourceName;
	}

	/**
	 * Given an input class object, return a string which consists of the class's package name as a pathname, i.e., all
	 * dots ('.') are replaced by slashes ('/'). Neither a leading nor trailing slash is added. The result could be
	 * concatenated with a slash and the name of a resource and fed directly to <code>ClassLoader.getResource()</code>.
	 * For it to be fed to <code>Class.getResource</code> instead, a leading slash would also have to be prepended to
	 * the returned value.
	 * @param clazz the input class. A <code>null</code> value or the default (empty) package will result in an empty
	 *            string ("") being returned.
	 * @return a path which represents the package name
	 * @see ClassLoader#getResource
	 * @see Class#getResource
	 */
	public static String classPackageAsResourcePath(Class<?> clazz) {
		if (clazz == null) {
			return "";
		}
		String className = clazz.getName();
		int packageEndIndex = className.lastIndexOf('.');
		if (packageEndIndex == -1) {
			return "";
		}
		String packageName = className.substring(0, packageEndIndex);
		return packageName.replace('.', '/');
	}

	/**
	 * Build a String that consists of the names of the classes/interfaces in the given array.
	 * <p>
	 * Basically like <code>AbstractCollection.toString()</code>, but stripping the "class "/"interface " prefix before
	 * every class name.
	 * @param classes a Collection of Class objects (may be <code>null</code>)
	 * @return a String of form "[com.foo.Bar, com.foo.Baz]"
	 * @see java.util.AbstractCollection#toString()
	 */
	@SuppressWarnings("rawtypes")
	public static String classNamesToString(Class... classes) {
		return classNamesToString(Arrays.asList(classes));
	}

	/**
	 * Build a String that consists of the names of the classes/interfaces in the given collection.
	 * <p>
	 * Basically like <code>AbstractCollection.toString()</code>, but stripping the "class "/"interface " prefix before
	 * every class name.
	 * @param classes a Collection of Class objects (may be <code>null</code>)
	 * @return a String of form "[com.foo.Bar, com.foo.Baz]"
	 * @see java.util.AbstractCollection#toString()
	 */
	@SuppressWarnings("rawtypes")
	public static String classNamesToString(Collection<Class> classes) {
		if (CollectionUtils.isEmpty(classes)) {
			return "[]";
		}
		StringBuilder sb = new StringBuilder("[");
		for (Iterator<Class> it = classes.iterator(); it.hasNext();) {
			Class clazz = it.next();
			sb.append(clazz.getName());
			if (it.hasNext()) {
				sb.append(", ");
			}
		}
		sb.append("]");
		return sb.toString();
	}


	/**
	 * Return all interfaces that the given instance implements as array, including ones implemented by superclasses.
	 * @param instance the instance to analyze for interfaces
	 * @return all interfaces that the given instance implements as array
	 */
	@SuppressWarnings("rawtypes")
	public static Class[] getAllInterfaces(Object instance) {
		Assert.notNull(instance, "Instance must not be null");
		return getAllInterfacesForClass(instance.getClass());
	}

	/**
	 * Return all interfaces that the given class implements as array, including ones implemented by superclasses.
	 * <p>
	 * If the class itself is an interface, it gets returned as sole interface.
	 * @param clazz the class to analyze for interfaces
	 * @return all interfaces that the given object implements as array
	 */
	public static Class<?>[] getAllInterfacesForClass(Class<?> clazz) {
		return getAllInterfacesForClass(clazz, null);
	}

	/**
	 * Return all interfaces that the given class implements as array, including ones implemented by superclasses.
	 * <p>
	 * If the class itself is an interface, it gets returned as sole interface.
	 * @param clazz the class to analyze for interfaces
	 * @param classLoader the ClassLoader that the interfaces need to be visible in (may be <code>null</code> when
	 *            accepting all declared interfaces)
	 * @return all interfaces that the given object implements as array
	 */
	@SuppressWarnings("rawtypes")
	public static Class<?>[] getAllInterfacesForClass(Class<?> clazz, ClassLoader classLoader) {
		Set<Class> ifcs = getAllInterfacesForClassAsSet(clazz, classLoader);
		return ifcs.toArray(new Class[ifcs.size()]);
	}

	/**
	 * Return all interfaces that the given instance implements as Set, including ones implemented by superclasses.
	 * @param instance the instance to analyze for interfaces
	 * @return all interfaces that the given instance implements as Set
	 */
	@SuppressWarnings("rawtypes")
	public static Set<Class> getAllInterfacesAsSet(Object instance) {
		Assert.notNull(instance, "Instance must not be null");
		return getAllInterfacesForClassAsSet(instance.getClass());
	}

	/**
	 * Return all interfaces that the given class implements as Set, including ones implemented by superclasses.
	 * <p>
	 * If the class itself is an interface, it gets returned as sole interface.
	 * @param clazz the class to analyze for interfaces
	 * @return all interfaces that the given object implements as Set
	 */
	@SuppressWarnings("rawtypes")
	public static Set<Class> getAllInterfacesForClassAsSet(Class clazz) {
		return getAllInterfacesForClassAsSet(clazz, null);
	}

	/**
	 * Return all interfaces that the given class implements as Set, including ones implemented by superclasses.
	 * <p>
	 * If the class itself is an interface, it gets returned as sole interface.
	 * @param clazz the class to analyze for interfaces
	 * @param classLoader the ClassLoader that the interfaces need to be visible in (may be <code>null</code> when
	 *            accepting all declared interfaces)
	 * @return all interfaces that the given object implements as Set
	 */
	@SuppressWarnings("rawtypes")
	public static Set<Class> getAllInterfacesForClassAsSet(Class clazz, ClassLoader classLoader) {
		Assert.notNull(clazz, "Class must not be null");
		if (clazz.isInterface() && isVisible(clazz, classLoader)) {
			return Collections.singleton(clazz);
		}
		Set<Class> interfaces = new LinkedHashSet<Class>();
		while (clazz != null) {
			Class<?>[] ifcs = clazz.getInterfaces();
			for (Class<?> ifc : ifcs) {
				interfaces.addAll(getAllInterfacesForClassAsSet(ifc, classLoader));
			}
			clazz = clazz.getSuperclass();
		}
		return interfaces;
	}

	/**
	 * Create a composite interface Class for the given interfaces, implementing the given interfaces in one single
	 * Class.
	 * <p>
	 * This implementation builds a JDK proxy class for the given interfaces.
	 * @param interfaces the interfaces to merge
	 * @param classLoader the ClassLoader to create the composite Class in
	 * @return the merged interface as Class
	 * @see java.lang.reflect.Proxy#getProxyClass
	 */
	public static Class<?> createCompositeInterface(Class<?>[] interfaces, ClassLoader classLoader) {
		Assert.notEmpty(interfaces, "Interfaces must not be empty");
		Assert.notNull(classLoader, "ClassLoader must not be null");
		return Proxy.getProxyClass(classLoader, interfaces);
	}

	/**
	 * Check whether the given class is visible in the given ClassLoader.
	 * @param clazz the class to check (typically an interface)
	 * @param classLoader the ClassLoader to check against (may be <code>null</code>, in which case this method will
	 *            always return <code>true</code>)
	 */
	public static boolean isVisible(Class<?> clazz, ClassLoader classLoader) {
		if (classLoader == null) {
			return true;
		}
		try {
			Class<?> actualClass = classLoader.loadClass(clazz.getName());
			return (clazz == actualClass);
			// Else: different interface class found...
		} catch (ClassNotFoundException ex) {
			// No interface class found...
			return false;
		}
	}

}
