classutils.java

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	/**
	 * 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) {
		return (clazz != null && clazz.getName().indexOf(CGLIB_CLASS_SEPARATOR) != -1 ?
				clazz.getSuperclass() : clazz);
	}


	/**
	 * 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));
	}

	/**
	 * Return the short string name of a Java class in decapitalized
	 * JavaBeans property format.
	 * @param clazz the class
	 * @return the short name rendered in a standard JavaBeans property format
	 * @see java.beans.Introspector#decapitalize(String)
	 */
	public static String getShortNameAsProperty(Class clazz) {
		return Introspector.decapitalize(getShortName(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) {
		StringBuffer buffer = new StringBuffer();
		while (clazz.isArray()) {
			clazz = clazz.getComponentType();
			buffer.append(ClassUtils.ARRAY_SUFFIX);
		}
		buffer.insert(0, clazz.getName());
		return buffer.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();
	}


	/**
	 * Determine whether the given class has a 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 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 Constructor getConstructorIfAvailable(Class 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 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;
		for (int i = 0; i < clazz.getDeclaredMethods().length; i++) {
			Method method = clazz.getDeclaredMethods()[i];
			if (methodName.equals(method.getName())) {
				count++;
			}
		}
		Class[] ifcs = clazz.getInterfaces();
		for (int i = 0; i < ifcs.length; i++) {
			count += getMethodCountForName(ifcs[i], methodName);
		}
		if (clazz.getSuperclass() != null) {
			count += getMethodCountForName(clazz.getSuperclass(), methodName);
		}
		return count;
	}

	/**
	 * Does the given class and/or its superclasses at least have one or more
	 * methods (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");
		for (int i = 0; i < clazz.getDeclaredMethods().length; i++) {
			Method method = clazz.getDeclaredMethods()[i];
			if (method.getName().equals(methodName)) {
				return true;
			}
		}
		Class[] ifcs = clazz.getInterfaces();
		for (int i = 0; i < ifcs.length; i++) {
			if (hasAtLeastOneMethodWithName(ifcs[i], methodName)) {
				return true;
			}
		}
		return (clazz.getSuperclass() != null && hasAtLeastOneMethodWithName(clazz.getSuperclass(), methodName));
	}

	/**
	 * Given a method, which may come from an interface, and a target class used
	 * in the current reflective invocation, find the corresponding target method
	 * if there is one. E.g. the method may be <code>IFoo.bar()</code> and the
	 * target class may be <code>DefaultFoo</code>. In this case, the method may be
	 * <code>DefaultFoo.bar()</code>. This enables attributes on that method to be found.
	 * <p><b>NOTE:</b> In contrast to {@link org.springframework.aop.support.AopUtils#getMostSpecificMethod},
	 * this method does <i>not</i> resolve Java 5 bridge methods automatically.
	 * Call {@link org.springframework.core.BridgeMethodResolver#findBridgedMethod}
	 * if bridge method resolution is desirable (e.g. for obtaining metadata from
	 * the original method definition).
	 * @param method the method to be invoked, which may come from an interface
	 * @param targetClass the target class for the current invocation.
	 * May be <code>null</code> or may not even implement the method.
	 * @return the specific target method, or the original method if the
	 * <code>targetClass</code> doesn't implement it or is <code>null</code>
	 * @see org.springframework.aop.support.AopUtils#getMostSpecificMethod
	 */
	public static Method getMostSpecificMethod(Method method, Class targetClass) {
		if (method != null && targetClass != null) {
			try {
				method = targetClass.getMethod(method.getName(), method.getParameterTypes());
			}
			catch (NoSuchMethodException ex) {
				// Perhaps the target class doesn't implement this method:
				// that's fine, just use the original method.
			}
		}
		return method;