org.springframework.util.ClassUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2007 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.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
*/
public abstract class ClassUtils {
/** Suffix for array class names */
public static final String ARRAY_SUFFIX = "[]";
/** 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 "$$" */
private static final String CGLIB_CLASS_SEPARATOR = "$$";
/** The ".class" file suffix */
private 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(8);
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 (Iterator it = primitiveWrapperTypeMap.values().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.
* 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
* Class.forName, which accepts a null ClassLoader
* reference as well).
* @return the default ClassLoader (never 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;
}
/**
* Determine whether the {@link Class} identified by the supplied name is present
* and can be loaded. Will return 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 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 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 Class.forName() that also returns Class instances
* for primitives (like "int") and array class names (like "String[]").
*
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 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 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;
}
if (name.endsWith(ARRAY_SUFFIX)) {
// special handling for array class names
String elementClassName = name.substring(0, name.length() - ARRAY_SUFFIX.length());
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[]").
*
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 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) {
throw new IllegalArgumentException("Cannot find class [" + className + "]. Root cause: " + ex);
}
catch (LinkageError ex) {
throw new IllegalArgumentException("Error loading class [" + className +
"]: problem with class file or dependent class. Root cause: " + ex);
}
}
/**
* Resolve the given class name as primitive class, if appropriate.
* @param name the name of the potentially primitive class
* @return the primitive class, or null if the name does not denote
* a primitive 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);
}
/**
* 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;
}
/**
* 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.
*
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 null).
*
Essentially translates NoSuchMethodException to null.
* @param clazz the clazz to analyze
* @param paramTypes the parameter types of the method
* @return the constructor, or 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.
*
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 null).
*
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 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(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));
}
/**
* 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 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.
*/
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).
*/
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.
*/
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.
*/
public static boolean isPrimitiveWrapperArray(Class clazz) {
Assert.notNull(clazz, "Class must not be null");
return (clazz.isArray() && isPrimitiveWrapper(clazz.getComponentType()));
}
/**
* Determine if the given target type is assignable from the given value
* type, assuming setting by reflection. Considers primitive wrapper
* classes as assignable to the corresponding primitive types.
* @param targetType the target type
* @param valueType the value type that should be assigned to the target type
* @return if the target type is assignable from the value type
*/
public static boolean isAssignable(Class targetType, Class valueType) {
Assert.notNull(targetType, "Target type must not be null");
Assert.notNull(valueType, "Value type must not be null");
return (targetType.isAssignableFrom(valueType) ||
targetType.equals(primitiveWrapperTypeMap.get(valueType)));
}
/**
* 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());
}
/**
* Return a path suitable for use with ClassLoader.getResource
* (also suitable for use with 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.
*
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 ClassLoader.getResource(). For it to be fed to
* Class.getResource instead, a leading slash would also have
* to be prepended to the returned value.
* @param clazz the input class. A 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.
*
Basically like AbstractCollection.toString(), but stripping
* the "class "/"interface " prefix before every class name.
* @param classes a Collection of Class objects (may be 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.
*
Basically like AbstractCollection.toString(), but stripping
* the "class "/"interface " prefix before every class name.
* @param classes a Collection of Class objects (may be 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.
*
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) {
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)) {
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.
*
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) {
Assert.notNull(clazz, "Class must not be null");
if (clazz.isInterface()) {
return Collections.singleton(clazz);
}
Set interfaces = new HashSet();
while (clazz != null) {
for (int i = 0; i < clazz.getInterfaces().length; i++) {
Class ifc = clazz.getInterfaces()[i];
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.
*
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);
}
}