org.springframework.util.ClassUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2005 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.Method;
import java.lang.reflect.Modifier;
import java.util.HashSet;
import java.util.Set;
/**
* Miscellaneous class utility methods. Mainly for internal use within the
* framework; consider Jakarta's Commons Lang for a more comprehensive suite
* of 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 = "[]";
/** All primitive classes */
private static Class[] PRIMITIVE_CLASSES = {
boolean.class, byte.class, char.class, short.class, int.class, long.class, float.class, double.class};
/** The package separator character '.' */
private static final char PACKAGE_SEPARATOR_CHAR = '.';
/** The inner class separator character '$' */
private static final char INNER_CLASS_SEPARATOR_CHAR = '$';
/** The CGLIB class separator character "$$" */
private static final String CGLIB_CLASS_SEPARATOR_CHAR = "$$";
/**
* Return a default ClassLoader to use (never null).
* Returns 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).
* @see java.lang.Thread#getContextClassLoader()
*/
public static ClassLoader getDefaultClassLoader() {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
if (cl == null) {
// No thread context class loader -> use class loader of this class.
cl = ClassUtils.class.getClassLoader();
}
return cl;
}
/**
* Replacement for Class.forName() that also returns Class instances
* for primitives (like "int") and array class names (like "String[]").
*
Always uses the thread context class loader.
* @param name the name of the Class
* @return Class instance for the supplied name
* @see java.lang.Class#forName(String, boolean, ClassLoader)
* @see java.lang.Thread#getContextClassLoader()
*/
public static Class forName(String name) throws ClassNotFoundException {
return forName(name, Thread.currentThread().getContextClassLoader());
}
/**
* 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
* @return Class instance for the supplied name
* @see java.lang.Class#forName(String, boolean, ClassLoader)
* @see java.lang.Thread#getContextClassLoader()
*/
public static Class forName(String name, ClassLoader classLoader) throws ClassNotFoundException {
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 = ClassUtils.forName(elementClassName, classLoader);
return Array.newInstance(elementClass, 0).getClass();
}
return Class.forName(name, true, classLoader);
}
/**
* 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) {
// Most class names will be quite long, considering that they
// SHOULD sit in a package, so a length check is worthwhile.
if (name.length() <= 8) {
// could be a primitive - likely
for (int i = 0; i < PRIMITIVE_CLASSES.length; i++) {
Class clazz = PRIMITIVE_CLASSES[i];
if (clazz.getName().equals(name)) {
return clazz;
}
}
}
return null;
}
/**
* 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));
}
/**
* 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
* @throws IllegalArgumentException if the class is null
*/
public static String getShortName(Class clazz) {
return getShortName(clazz.getName());
}
/**
* 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_CHAR);
int nameEndIndex = className.indexOf(CGLIB_CLASS_SEPARATOR_CHAR);
if (nameEndIndex == -1) {
nameEndIndex = className.length();
}
String shortName = className.substring(lastDotIndex + 1, nameEndIndex);
shortName = shortName.replace(INNER_CLASS_SEPARATOR_CHAR, PACKAGE_SEPARATOR_CHAR);
return shortName;
}
/**
* 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 empty");
return method.getDeclaringClass().getName() + "." + method.getName();
}
/**
* 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
*/
public static boolean hasMethod(Class clazz, String methodName, Class[] paramTypes) {
try {
clazz.getMethod(methodName, paramTypes);
return true;
}
catch (NoSuchMethodException ex) {
return false;
}
}
/**
* 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) {
int count = 0;
do {
for (int i = 0; i < clazz.getDeclaredMethods().length; i++) {
Method method = clazz.getDeclaredMethods()[i];
if (methodName.equals(method.getName())) {
count++;
}
}
clazz = clazz.getSuperclass();
}
while (clazz != null);
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) {
do {
for (int i = 0; i < clazz.getDeclaredMethods().length; i++) {
Method method = clazz.getDeclaredMethods()[i];
if (methodName.equals(method.getName())) {
return true;
}
}
clazz = clazz.getSuperclass();
}
while (clazz != null);
return false;
}
/**
* 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) {
try {
Method method = clazz.getDeclaredMethod(methodName, args);
if ((method.getModifiers() & Modifier.STATIC) != 0) {
return method;
}
} catch (NoSuchMethodException ex) {
}
return null;
}
/**
* 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) {
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,
* a leading slash would also have to be prepended to the return 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 java.lang.ClassLoader#getResource
* @see java.lang.Class#getResource
*/
public static String classPackageAsResourcePath(Class clazz) {
if (clazz == null || clazz.getPackage() == null) {
return "";
}
return clazz.getPackage().getName().replace('.', '/');
}
/**
* Return all interfaces that the given object implements as array,
* including ones implemented by superclasses.
* @param object the object to analyse for interfaces
* @return all interfaces that the given object implements as array
*/
public static Class[] getAllInterfaces(Object object) {
Set interfaces = getAllInterfacesAsSet(object);
return (Class[]) interfaces.toArray(new Class[interfaces.size()]);
}
/**
* Return all interfaces that the given class implements as array,
* including ones implemented by superclasses.
* @param clazz the class to analyse for interfaces
* @return all interfaces that the given object implements as array
*/
public static Class[] getAllInterfacesForClass(Class clazz) {
Set interfaces = getAllInterfacesForClassAsSet(clazz);
return (Class[]) interfaces.toArray(new Class[interfaces.size()]);
}
/**
* Return all interfaces that the given object implements as List,
* including ones implemented by superclasses.
* @param object the object to analyse for interfaces
* @return all interfaces that the given object implements as List
*/
public static Set getAllInterfacesAsSet(Object object) {
return getAllInterfacesForClassAsSet(object.getClass());
}
/**
* Return all interfaces that the given class implements as Set,
* including ones implemented by superclasses.
* @param clazz the class to analyse for interfaces
* @return all interfaces that the given object implements as Set
*/
public static Set getAllInterfacesForClassAsSet(Class 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;
}
}