Java tutorial
/* * Copyright 2002-2008 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 com.jeeframework.util.classes; import java.beans.Introspector; 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.ArrayList; 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.List; import java.util.Map; import java.util.Set; import com.jeeframework.util.collection.CollectionUtils; import com.jeeframework.util.validate.Assert; /** * Miscellaneous class utility methods. Mainly for internal use within the * framework; consider Jakarta's Commons Lang for a more comprehensive suite * of class utilities. * * @author Keith Donald * @author Rob Harrop * @author Juergen Hoeller * @since 1.1 * @see TypeUtils * @see ReflectionUtils */ public abstract class ClassUtils { /** Suffix for array class names: "[]" */ public static final String ARRAY_SUFFIX = "[]"; /** Prefix for internal array class names: "[L" */ private static final String INTERNAL_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 primitiveWrapperTypeMap = new HashMap(8); /** * Map with primitive type name as key and corresponding primitive * type as value, for example: "int" -> "int.class". */ private static final Map primitiveTypeNameMap = new HashMap(16); 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); Set primitiveTypeNames = new HashSet(16); primitiveTypeNames.addAll(primitiveWrapperTypeMap.values()); primitiveTypeNames.addAll(Arrays.asList(new Class[] { boolean[].class, byte[].class, char[].class, double[].class, float[].class, int[].class, long[].class, short[].class })); for (Iterator it = primitiveTypeNames.iterator(); it.hasNext();) { Class primitiveClass = (Class) it.next(); primitiveTypeNameMap.put(primitiveClass.getName(), primitiveClass); } } /** * 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; } } /** * 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 */ 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; } } /** * 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() */ 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 (like "int") and array class names (like "String[]"). * @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) { 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 int internalArrayMarker = name.indexOf(INTERNAL_ARRAY_PREFIX); if (internalArrayMarker != -1 && name.endsWith(";")) { String elementClassName = null; if (internalArrayMarker == 0) { elementClassName = name.substring(INTERNAL_ARRAY_PREFIX.length(), name.length() - 1); } else if (name.startsWith("[")) { elementClassName = name.substring(1); } Class elementClass = forName(elementClassName, classLoader); return Array.newInstance(elementClass, 0).getClass(); } ClassLoader classLoaderToUse = classLoader; if (classLoaderToUse == null) { classLoaderToUse = getDefaultClassLoader(); } return classLoaderToUse.loadClass(name); } /** * 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) { IllegalArgumentException iae = new IllegalArgumentException("Cannot find class [" + className + "]"); iae.initCause(ex); throw iae; } catch (LinkageError ex) { IllegalArgumentException iae = new IllegalArgumentException( "Error loading class [" + className + "]: problem with class file or dependent class."); iae.initCause(ex); throw iae; } } /** * 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}. * @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 = (Class) primitiveTypeNameMap.get(name); } return result; } /** * 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); } /** * 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)); } /** * Return the short string name of a Java class in decapitalized JavaBeans * property format. Strips the outer class name in case of an inner class. * @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) { String shortName = ClassUtils.getShortName(clazz); int dotIndex = shortName.lastIndexOf('.'); shortName = (dotIndex != -1 ? shortName.substring(dotIndex + 1) : shortName); return Introspector.decapitalize(shortName); } /** * 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(); } /** * 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)) { StringBuffer buf = new StringBuffer(clazz.getName()); buf.append(" implementing "); Class[] ifcs = clazz.getInterfaces(); for (int i = 0; i < ifcs.length; i++) { buf.append(ifcs[i].getName()); if (i < ifcs.length - 1) { buf.append(','); } } return buf.toString(); } else if (clazz.isArray()) { return getQualifiedNameForArray(clazz); } else { return clazz.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; Method[] declaredMethods = clazz.getDeclaredMethods(); for (int i = 0; i < declaredMethods.length; i++) { Method method = declaredMethods[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"); Method[] declaredMethods = clazz.getDeclaredMethods(); for (int i = 0; i < declaredMethods.length; i++) { Method method = declaredMethods[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 && !targetClass.equals(method.getDeclaringClass())) { 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; } /** * Return a 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.getDeclaredMethod(methodName, args); if ((method.getModifiers() & Modifier.STATIC) != 0) { return method; } } 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())); } /** * 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 */ 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"); return (lhsType.isAssignableFrom(rhsType) || lhsType.equals(primitiveWrapperTypeMap.get(rhsType))); } /** * 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) { 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) { 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 necesssary, 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() */ 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() */ public static String classNamesToString(Collection classes) { if (CollectionUtils.isEmpty(classes)) { return "[]"; } StringBuffer sb = new StringBuffer("["); for (Iterator it = classes.iterator(); it.hasNext();) { Class clazz = (Class) 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 analyse for interfaces * @return all interfaces that the given instance implements as array */ 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 analyse 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 analyse 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 */ public static Class[] getAllInterfacesForClass(Class clazz, ClassLoader classLoader) { Assert.notNull(clazz, "Class must not be null"); if (clazz.isInterface()) { return new Class[] { clazz }; } List interfaces = new ArrayList(); while (clazz != null) { for (int i = 0; i < clazz.getInterfaces().length; i++) { Class ifc = clazz.getInterfaces()[i]; if (!interfaces.contains(ifc) && (classLoader == null || isVisible(ifc, classLoader))) { interfaces.add(ifc); } } clazz = clazz.getSuperclass(); } return (Class[]) interfaces.toArray(new Class[interfaces.size()]); } /** * Return all interfaces that the given instance implements as Set, * including ones implemented by superclasses. * @param instance the instance to analyse for interfaces * @return all interfaces that the given instance implements as Set */ public static Set 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 analyse for interfaces * @return all interfaces that the given object implements as Set */ public static Set 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 analyse 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 */ public static Set getAllInterfacesForClassAsSet(Class clazz, ClassLoader classLoader) { Assert.notNull(clazz, "Class must not be null"); if (clazz.isInterface()) { return Collections.singleton(clazz); } Set interfaces = new LinkedHashSet(); while (clazz != null) { for (int i = 0; i < clazz.getInterfaces().length; i++) { Class ifc = clazz.getInterfaces()[i]; if (classLoader == null || isVisible(ifc, classLoader)) { interfaces.add(ifc); } } 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; } } }