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The Spring Framework ClassUtils.java source code
/*
* 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 org.springframework.util;
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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* 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";
private static final Log logger = LogFactory.getLog(ClassUtils.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, which accepts a null ClassLoader
* reference as well).
* @return the default ClassLoader (never <code>null)
* @see java.lang.Thread#getContextClassLoader()
*/
public static ClassLoader getDefaultClassLoader() {
ClassLoader cl = null;
try {
cl = Thread.currentThread().getContextClassLoader();
}
catch (Throwable ex) {
logger.debug("Cannot access thread context ClassLoader - falling back to system class loader", ex);
}
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 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 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 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, 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) {
if (logger.isDebugEnabled()) {
logger.debug("Class [" + className + "] or one of its dependencies is not present: " + ex);
}
return false;
}
}
/**
* Replacement for <code>Class.forName() 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() 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, 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 forName
* 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, 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 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 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 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 NoSuchMethodException 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).
* <p>Essentially translates NoSuchMethodException to null.
* @param clazz the clazz to analyze
* @param paramTypes the parameter types of the method
* @return the constructor, or <code>null 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 NoSuchMethodException 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).
* <p>Essentially translates NoSuchMethodException to null.
* @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 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(final Class clazz, final String methodName) {
Assert.notNull(clazz, "Class must not be null");
Assert.notNull(methodName, "Method name must not be null");
int count = 0;
final 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(final Class clazz, final String methodName) {
Assert.notNull(clazz, "Class must not be null");
Assert.notNull(methodName, "Method name must not be null");
final 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() and the
* target class may be <code>DefaultFoo. In this case, the method may be
* <code>DefaultFoo.bar(). This enables attributes on that method to be found.
* <p>NOTE: In contrast to {@link org.springframework.aop.support.AopUtils#getMostSpecificMethod},
* this method does <i>not 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 or may not even implement the method.
* @return the specific target method, or the original method if the
* <code>targetClass doesn't implement it or is null
* @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 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
* (also suitable for use with <code>Class.getResource 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(). For it to be fed to
* <code>Class.getResource instead, a leading slash would also have
* to be prepended to the returned value.
* @param clazz the input class. A <code>null 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 AbstractCollection.toString(), but stripping
* the "class "/"interface " prefix before every class name.
* @param classes a Collection of Class objects (may be <code>null)
* @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 AbstractCollection.toString(), but stripping
* the "class "/"interface " prefix before every class name.
* @param classes a Collection of Class objects (may be <code>null)
* @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 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 || isInterfaceVisible(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 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 || isInterfaceVisible(ifc, classLoader)) {
interfaces.add(ifc);
}
}
clazz = clazz.getSuperclass();
}
return interfaces;
}
/**
* Check whether the given interface is visible in the given ClassLoader.
* @param ifc the interface to check
* @param classLoader the ClassLoader to check against
*/
private static boolean isInterfaceVisible(Class ifc, ClassLoader classLoader) {
try {
Class interfaceClass = classLoader.loadClass(ifc.getName());
if (ifc == interfaceClass) {
return true;
}
else {
// Different interface class found...
if (logger.isDebugEnabled()) {
logger.debug("Ignoring interface [" + ifc.getName() + "] - " +
"different class of same name visible in Classloader [" + classLoader + "]");
}
}
}
catch (ClassNotFoundException ex) {
// No interface class found...
if (logger.isDebugEnabled()) {
logger.debug("Ignoring interface [" + ifc.getName() + "] - " +
"not visible in Classloader [" + classLoader + "]: " + ex);
}
}
return false;
}
/**
* 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);
}
}
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