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ClassUtils.java
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1736 lines (1642 loc) · 72.3 KB
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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
*
* https://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.apache.commons.lang3;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Deque;
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.Objects;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.Collectors;
/**
* Operates on classes without using reflection.
*
* <p>
* This class handles invalid {@code null} inputs as best it can. Each method documents its behavior in more detail.
* </p>
*
* <p>
* The notion of a {@code canonical name} includes the human-readable name for the type, for example {@code int[]}. The
* non-canonical method variants work with the JVM names, such as {@code [I}.
* </p>
*
* @since 2.0
*/
public class ClassUtils {
/**
* Inclusivity literals for {@link #hierarchy(Class, Interfaces)}.
*
* @since 3.2
*/
public enum Interfaces {
/** Includes interfaces. */
INCLUDE,
/** Excludes interfaces. */
EXCLUDE
}
/**
* The JLS-specified maximum class name length {@value}.
*
* @see Class#forName(String, boolean, ClassLoader)
* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.4.1">JVM: Array dimension limits in JVM Specification CONSTANT_Class_info</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-6.html#jls-6.7">JLS: Fully Qualified Names and Canonical Names</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-13.html#jls-13.1">JLS: The Form of a Binary</a>
*/
private static final int MAX_CLASS_NAME_LENGTH = 65535;
/**
* The JVM-specified {@code CONSTANT_Class_info} structure defines an array type descriptor is valid only if it represents {@value} or fewer dimensions.
*
* @see Class#forName(String, boolean, ClassLoader)
* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.4.1">JVM: Array dimension limits in JVM Specification CONSTANT_Class_info</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-6.html#jls-6.7">JLS: Fully Qualified Names and Canonical Names</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-13.html#jls-13.1">JLS: The Form of a Binary</a>
*/
private static final int MAX_JVM_ARRAY_DIMENSION = 255;
/**
* The maximum number of array dimensions.
*/
private static final int MAX_DIMENSIONS = 255;
private static final Comparator<Class<?>> COMPARATOR = (o1, o2) -> Objects.compare(getName(o1), getName(o2), String::compareTo);
/**
* The package separator character: {@code '.' == {@value}}.
*/
public static final char PACKAGE_SEPARATOR_CHAR = '.';
/**
* The package separator String: {@code "."}.
*/
public static final String PACKAGE_SEPARATOR = String.valueOf(PACKAGE_SEPARATOR_CHAR);
/**
* The inner class separator character: {@code '$' == {@value}}.
*/
public static final char INNER_CLASS_SEPARATOR_CHAR = '$';
/**
* The inner class separator String: {@code "$"}.
*/
public static final String INNER_CLASS_SEPARATOR = String.valueOf(INNER_CLASS_SEPARATOR_CHAR);
/**
* Maps names of primitives to their corresponding primitive {@link Class}es.
*/
private static final Map<String, Class<?>> NAME_PRIMITIVE_MAP = new HashMap<>();
static {
NAME_PRIMITIVE_MAP.put(Boolean.TYPE.getName(), Boolean.TYPE);
NAME_PRIMITIVE_MAP.put(Byte.TYPE.getName(), Byte.TYPE);
NAME_PRIMITIVE_MAP.put(Character.TYPE.getName(), Character.TYPE);
NAME_PRIMITIVE_MAP.put(Double.TYPE.getName(), Double.TYPE);
NAME_PRIMITIVE_MAP.put(Float.TYPE.getName(), Float.TYPE);
NAME_PRIMITIVE_MAP.put(Integer.TYPE.getName(), Integer.TYPE);
NAME_PRIMITIVE_MAP.put(Long.TYPE.getName(), Long.TYPE);
NAME_PRIMITIVE_MAP.put(Short.TYPE.getName(), Short.TYPE);
NAME_PRIMITIVE_MAP.put(Void.TYPE.getName(), Void.TYPE);
}
/**
* Maps primitive {@link Class}es to their corresponding wrapper {@link Class}.
*/
private static final Map<Class<?>, Class<?>> PRIMITIVE_WRAPPER_MAP = new HashMap<>();
static {
PRIMITIVE_WRAPPER_MAP.put(Boolean.TYPE, Boolean.class);
PRIMITIVE_WRAPPER_MAP.put(Byte.TYPE, Byte.class);
PRIMITIVE_WRAPPER_MAP.put(Character.TYPE, Character.class);
PRIMITIVE_WRAPPER_MAP.put(Short.TYPE, Short.class);
PRIMITIVE_WRAPPER_MAP.put(Integer.TYPE, Integer.class);
PRIMITIVE_WRAPPER_MAP.put(Long.TYPE, Long.class);
PRIMITIVE_WRAPPER_MAP.put(Double.TYPE, Double.class);
PRIMITIVE_WRAPPER_MAP.put(Float.TYPE, Float.class);
PRIMITIVE_WRAPPER_MAP.put(Void.TYPE, Void.TYPE);
}
/**
* Maps wrapper {@link Class}es to their corresponding primitive types.
*/
private static final Map<Class<?>, Class<?>> WRAPPER_PRIMITIVE_MAP = new HashMap<>();
static {
PRIMITIVE_WRAPPER_MAP.forEach((primitiveClass, wrapperClass) -> {
if (!primitiveClass.equals(wrapperClass)) {
WRAPPER_PRIMITIVE_MAP.put(wrapperClass, primitiveClass);
}
});
}
/**
* Maps a primitive class name to its corresponding abbreviation used in array class names.
*/
private static final Map<String, String> ABBREVIATION_MAP;
/**
* Maps an abbreviation used in array class names to corresponding primitive class name.
*/
private static final Map<String, String> REVERSE_ABBREVIATION_MAP;
/** Feed abbreviation maps. */
static {
final Map<String, String> map = new HashMap<>();
map.put(Integer.TYPE.getName(), "I");
map.put(Boolean.TYPE.getName(), "Z");
map.put(Float.TYPE.getName(), "F");
map.put(Long.TYPE.getName(), "J");
map.put(Short.TYPE.getName(), "S");
map.put(Byte.TYPE.getName(), "B");
map.put(Double.TYPE.getName(), "D");
map.put(Character.TYPE.getName(), "C");
ABBREVIATION_MAP = Collections.unmodifiableMap(map);
REVERSE_ABBREVIATION_MAP = Collections.unmodifiableMap(map.entrySet().stream().collect(Collectors.toMap(Map.Entry::getValue, Map.Entry::getKey)));
}
/**
* Gets the class comparator, comparing by class name.
*
* @return the class comparator.
* @since 3.13.0
*/
public static Comparator<Class<?>> comparator() {
return COMPARATOR;
}
/**
* Given a {@link List} of {@link Class} objects, this method converts them into class names.
*
* <p>
* A new {@link List} is returned. {@code null} objects will be copied into the returned list as {@code null}.
* </p>
*
* @param classes the classes to change.
* @return a {@link List} of class names corresponding to the Class objects, {@code null} if null input.
* @throws ClassCastException if {@code classes} contains a non-{@link Class} entry.
*/
public static List<String> convertClassesToClassNames(final List<Class<?>> classes) {
return classes == null ? null : classes.stream().map(e -> getName(e, null)).collect(Collectors.toList());
}
/**
* Given a {@link List} of class names, this method converts them into classes.
*
* <p>
* A new {@link List} is returned. If the class name cannot be found, {@code null} is stored in the {@link List}. If the
* class name in the {@link List} is {@code null}, {@code null} is stored in the output {@link List}.
* </p>
*
* @param classNames the classNames to change.
* @return a {@link List} of Class objects corresponding to the class names, {@code null} if null input.
* @throws ClassCastException if classNames contains a non String entry.
*/
public static List<Class<?>> convertClassNamesToClasses(final List<String> classNames) {
if (classNames == null) {
return null;
}
final List<Class<?>> classes = new ArrayList<>(classNames.size());
classNames.forEach(className -> {
try {
classes.add(Class.forName(className));
} catch (final Exception ex) {
classes.add(null);
}
});
return classes;
}
/**
* Gets the abbreviated name of a {@link Class}.
*
* @param cls the class to get the abbreviated name for, may be {@code null}.
* @param lengthHint the desired length of the abbreviated name.
* @return the abbreviated name or an empty string.
* @throws IllegalArgumentException if len <= 0.
* @see #getAbbreviatedName(String, int)
* @since 3.4
*/
public static String getAbbreviatedName(final Class<?> cls, final int lengthHint) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getAbbreviatedName(cls.getName(), lengthHint);
}
/**
* Gets the abbreviated class name from a {@link String}.
*
* <p>
* The string passed in is assumed to be a class name - it is not checked.
* </p>
*
* <p>
* The abbreviation algorithm will shorten the class name, usually without significant loss of meaning.
* </p>
*
* <p>
* The abbreviated class name will always include the complete package hierarchy. If enough space is available,
* rightmost sub-packages will be displayed in full length. The abbreviated package names will be shortened to a single
* character.
* </p>
* <p>
* Only package names are shortened, the class simple name remains untouched. (See examples.)
* </p>
* <p>
* The result will be longer than the desired length only if all the package names shortened to a single character plus
* the class simple name with the separating dots together are longer than the desired length. In other words, when the
* class name cannot be shortened to the desired length.
* </p>
* <p>
* If the class name can be shortened then the final length will be at most {@code lengthHint} characters.
* </p>
* <p>
* If the {@code lengthHint} is zero or negative then the method throws exception. If you want to achieve the shortest
* possible version then use {@code 1} as a {@code lengthHint}.
* </p>
*
* <table>
* <caption>Examples</caption>
* <tr>
* <td>className</td>
* <td>len</td>
* <td>return</td>
* </tr>
* <tr>
* <td>null</td>
* <td>1</td>
* <td>""</td>
* </tr>
* <tr>
* <td>"java.lang.String"</td>
* <td>5</td>
* <td>"j.l.String"</td>
* </tr>
* <tr>
* <td>"java.lang.String"</td>
* <td>15</td>
* <td>"j.lang.String"</td>
* </tr>
* <tr>
* <td>"java.lang.String"</td>
* <td>30</td>
* <td>"java.lang.String"</td>
* </tr>
* <tr>
* <td>"org.apache.commons.lang3.ClassUtils"</td>
* <td>18</td>
* <td>"o.a.c.l.ClassUtils"</td>
* </tr>
* </table>
*
* @param className the className to get the abbreviated name for, may be {@code null}.
* @param lengthHint the desired length of the abbreviated name.
* @return the abbreviated name or an empty string if the specified class name is {@code null} or empty string. The
* abbreviated name may be longer than the desired length if it cannot be abbreviated to the desired length.
* @throws IllegalArgumentException if {@code len <= 0}.
* @since 3.4
*/
public static String getAbbreviatedName(final String className, final int lengthHint) {
if (lengthHint <= 0) {
throw new IllegalArgumentException("len must be > 0");
}
if (className == null) {
return StringUtils.EMPTY;
}
if (className.length() <= lengthHint) {
return className;
}
final char[] abbreviated = className.toCharArray();
int target = 0;
int source = 0;
while (source < abbreviated.length) {
// copy the next part
int runAheadTarget = target;
while (source < abbreviated.length && abbreviated[source] != '.') {
abbreviated[runAheadTarget++] = abbreviated[source++];
}
++target;
if (useFull(runAheadTarget, source, abbreviated.length, lengthHint) || target > runAheadTarget) {
target = runAheadTarget;
}
// copy the '.' unless it was the last part
if (source < abbreviated.length) {
abbreviated[target++] = abbreviated[source++];
}
}
return new String(abbreviated, 0, target);
}
/**
* Gets a {@link List} of all interfaces implemented by the given class and its superclasses.
*
* <p>
* The order is determined by looking through each interface in turn as declared in the source file and following its
* hierarchy up. Then each superclass is considered in the same way. Later duplicates are ignored, so the order is
* maintained.
* </p>
*
* @param cls the class to look up, may be {@code null}.
* @return the {@link List} of interfaces in order, {@code null} if null input.
*/
public static List<Class<?>> getAllInterfaces(final Class<?> cls) {
if (cls == null) {
return null;
}
final LinkedHashSet<Class<?>> interfacesFound = new LinkedHashSet<>();
getAllInterfaces(cls, interfacesFound);
return new ArrayList<>(interfacesFound);
}
/**
* Gets the interfaces for the specified class.
*
* @param cls the class to look up, may be {@code null}.
* @param interfacesFound the {@link Set} of interfaces for the class.
*/
private static void getAllInterfaces(Class<?> cls, final Set<Class<?>> interfacesFound) {
while (cls != null) {
for (final Class<?> i : cls.getInterfaces()) {
if (interfacesFound.add(i)) {
getAllInterfaces(i, interfacesFound);
}
}
cls = cls.getSuperclass();
}
}
/**
* Gets a {@link List} of superclasses for the given class.
*
* <ol>
* <li>The first entry is the superclass of the given class.</li>
* <li>The last entry is {@link Object}'s class.</li>
* </ol>
*
* @param cls the class to look up, may be {@code null}.
* @return the {@link List} of superclasses in order going up from this one {@code null} if null input.
*/
public static List<Class<?>> getAllSuperclasses(final Class<?> cls) {
if (cls == null) {
return null;
}
final List<Class<?>> classes = new ArrayList<>();
Class<?> superclass = cls.getSuperclass();
while (superclass != null) {
classes.add(superclass);
superclass = superclass.getSuperclass();
}
return classes;
}
/**
* Gets the canonical class name for a {@link Class}.
*
* @param cls the class for which to get the canonical class name; may be null.
* @return the canonical name of the class, or the empty String.
* @since 3.7
* @see Class#getCanonicalName()
*/
public static String getCanonicalName(final Class<?> cls) {
return getCanonicalName(cls, StringUtils.EMPTY);
}
/**
* Gets the canonical name for a {@link Class}.
*
* @param cls the class for which to get the canonical class name; may be null.
* @param valueIfNull the return value if null.
* @return the canonical name of the class, or {@code valueIfNull}.
* @since 3.7
* @see Class#getCanonicalName()
*/
public static String getCanonicalName(final Class<?> cls, final String valueIfNull) {
if (cls == null) {
return valueIfNull;
}
final String canonicalName = cls.getCanonicalName();
return canonicalName == null ? valueIfNull : canonicalName;
}
/**
* Gets the canonical name for an {@link Object}.
*
* @param object the object for which to get the canonical class name; may be null.
* @return the canonical name of the object, or the empty String.
* @since 3.7
* @see Class#getCanonicalName()
*/
public static String getCanonicalName(final Object object) {
return getCanonicalName(object, StringUtils.EMPTY);
}
/**
* Gets the canonical name for an {@link Object}.
*
* @param object the object for which to get the canonical class name; may be null.
* @param valueIfNull the return value if null.
* @return the canonical name of the object or {@code valueIfNull}.
* @since 3.7
* @see Class#getCanonicalName()
*/
public static String getCanonicalName(final Object object, final String valueIfNull) {
if (object == null) {
return valueIfNull;
}
final String canonicalName = object.getClass().getCanonicalName();
return canonicalName == null ? valueIfNull : canonicalName;
}
/**
* Converts a given name of class into canonical format. If name of class is not a name of array class it returns
* unchanged name.
*
* <p>
* The method does not change the {@code $} separators in case the class is inner class.
* </p>
*
* <p>
* Example:
* <ul>
* <li>{@code getCanonicalName("[I") = "int[]"}</li>
* <li>{@code getCanonicalName("[Ljava.lang.String;") = "java.lang.String[]"}</li>
* <li>{@code getCanonicalName("java.lang.String") = "java.lang.String"}</li>
* </ul>
* </p>
*
* @param name the name of class.
* @return canonical form of class name.
* @throws IllegalArgumentException if the class name is invalid.
*/
private static String getCanonicalName(final String name) {
String className = StringUtils.deleteWhitespace(name);
if (className == null) {
return null;
}
int dim = 0;
final int len = className.length();
while (dim < len && className.charAt(dim) == '[') {
dim++;
if (dim > MAX_DIMENSIONS) {
throw new IllegalArgumentException(String.format("Maximum array dimension %d exceeded", MAX_DIMENSIONS));
}
}
if (dim >= len) {
throw new IllegalArgumentException(String.format("Invalid class name %s", name));
}
if (dim < 1) {
return className;
}
className = className.substring(dim);
if (className.startsWith("L")) {
if (!className.endsWith(";") || className.length() < 3) {
throw new IllegalArgumentException(String.format("Invalid class name %s", name));
}
className = className.substring(1, className.length() - 1);
} else if (className.length() == 1) {
final String primitive = REVERSE_ABBREVIATION_MAP.get(className.substring(0, 1));
if (primitive == null) {
throw new IllegalArgumentException(String.format("Invalid class name %s", name));
}
className = primitive;
} else {
throw new IllegalArgumentException(String.format("Invalid class name %s", name));
}
final StringBuilder canonicalClassNameBuffer = new StringBuilder(className.length() + dim * 2);
canonicalClassNameBuffer.append(className);
for (int i = 0; i < dim; i++) {
canonicalClassNameBuffer.append("[]");
}
return canonicalClassNameBuffer.toString();
}
/**
* Gets the (initialized) class represented by {@code className} using the {@code classLoader}. This implementation
* supports the syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}",
* "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}".
* <p>
* The provided class name is normalized by removing all whitespace. This is especially helpful when handling XML element values in which whitespace has not
* been collapsed.
* </p>
*
* @param classLoader the class loader to use to load the class.
* @param className the class name.
* @return the class represented by {@code className} using the {@code classLoader}.
* @throws NullPointerException if the className is null.
* @throws ClassNotFoundException if the class is not found.
* @throws IllegalArgumentException Thrown if the class name represents an array with more dimensions than the JVM supports, 255.
* @throws IllegalArgumentException Thrown if the class name length is greater than 65,535.
* @see Class#forName(String, boolean, ClassLoader)
* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.4.1">JVM: Array dimension limits in JVM Specification CONSTANT_Class_info</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-6.html#jls-6.7">JLS: Fully Qualified Names and Canonical Names</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-13.html#jls-13.1">JLS: The Form of a Binary</a>
*/
public static Class<?> getClass(final ClassLoader classLoader, final String className) throws ClassNotFoundException {
return getClass(classLoader, className, true);
}
/**
* Gets the class represented by {@code className} using the {@code classLoader}. This implementation supports the
* syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}", "{@code [Ljava.util.Map.Entry;}", and
* "{@code [Ljava.util.Map$Entry;}".
* <p>
* The provided class name is normalized by removing all whitespace. This is especially helpful when handling XML element values in which whitespace has not
* been collapsed.
* </p>
*
* @param classLoader the class loader to use to load the class.
* @param className the class name.
* @param initialize whether the class must be initialized.
* @return the class represented by {@code className} using the {@code classLoader}.
* @throws NullPointerException if the className is null.
* @throws ClassNotFoundException if the class is not found.
* @throws IllegalArgumentException Thrown if the class name represents an array with more dimensions than the JVM supports, 255.
* @throws IllegalArgumentException Thrown if the class name length is greater than 65,535.
* @see Class#forName(String, boolean, ClassLoader)
* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.4.1">JVM: Array dimension limits in JVM Specification CONSTANT_Class_info</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-6.html#jls-6.7">JLS: Fully Qualified Names and Canonical Names</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-13.html#jls-13.1">JLS: The Form of a Binary</a>
*/
public static Class<?> getClass(final ClassLoader classLoader, final String className, final boolean initialize) throws ClassNotFoundException {
// This method was re-written to avoid recursion and stack overflows found by fuzz testing.
String next = className;
int lastDotIndex = -1;
do {
try {
final Class<?> clazz = getPrimitiveClass(next);
return clazz != null ? clazz : Class.forName(toCleanName(next), initialize, classLoader);
} catch (final ClassNotFoundException ex) {
lastDotIndex = next.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (lastDotIndex != -1) {
next = next.substring(0, lastDotIndex) + INNER_CLASS_SEPARATOR_CHAR + next.substring(lastDotIndex + 1);
}
}
} while (lastDotIndex != -1);
throw new ClassNotFoundException(className);
}
/**
* Gets the (initialized) class represented by {@code className} using the current thread's context class loader.
* This implementation supports the syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}",
* "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}".
* <p>
* The provided class name is normalized by removing all whitespace. This is especially helpful when handling XML element values in which whitespace has not
* been collapsed.
* </p>
*
* @param className the class name
* @return the class represented by {@code className} using the current thread's context class loader
* @throws NullPointerException if the className is null
* @throws ClassNotFoundException if the class is not found
* @throws IllegalArgumentException Thrown if the class name represents an array with more dimensions than the JVM supports, 255.
* @throws IllegalArgumentException Thrown if the class name length is greater than 65,535.
* @see Class#forName(String, boolean, ClassLoader)
* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.4.1">JVM: Array dimension limits in JVM Specification CONSTANT_Class_info</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-6.html#jls-6.7">JLS: Fully Qualified Names and Canonical Names</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-13.html#jls-13.1">JLS: The Form of a Binary</a>
*/
public static Class<?> getClass(final String className) throws ClassNotFoundException {
return getClass(className, true);
}
/**
* Gets the class represented by {@code className} using the current thread's context class loader. This
* implementation supports the syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}",
* "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}".
* <p>
* The provided class name is normalized by removing all whitespace. This is especially helpful when handling XML element values in which whitespace has not
* been collapsed.
* </p>
*
* @param className the class name.
* @param initialize whether the class must be initialized.
* @return the class represented by {@code className} using the current thread's context class loader.
* @throws NullPointerException if the className is null.
* @throws ClassNotFoundException if the class is not found.
* @throws IllegalArgumentException Thrown if the class name represents an array with more dimensions than the JVM supports, 255.
* @throws IllegalArgumentException Thrown if the class name length is greater than 65,535.
* @see Class#forName(String, boolean, ClassLoader)
* @see <a href="https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.4.1">JVM: Array dimension limits in JVM Specification CONSTANT_Class_info</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-6.html#jls-6.7">JLS: Fully Qualified Names and Canonical Names</a>
* @see <a href="https://docs.oracle.com/javase/specs/jls/se25/html/jls-13.html#jls-13.1">JLS: The Form of a Binary</a>
*/
public static Class<?> getClass(final String className, final boolean initialize) throws ClassNotFoundException {
final ClassLoader contextCL = Thread.currentThread().getContextClassLoader();
final ClassLoader loader = contextCL == null ? ClassUtils.class.getClassLoader() : contextCL;
return getClass(loader, className, initialize);
}
/**
* Delegates to {@link Class#getComponentType()} using generics.
*
* @param <T> The array class type.
* @param cls A class or null.
* @return The array component type or null.
* @see Class#getComponentType()
* @since 3.13.0
*/
@SuppressWarnings("unchecked")
public static <T> Class<T> getComponentType(final Class<T[]> cls) {
return cls == null ? null : (Class<T>) cls.getComponentType();
}
/**
* Null-safe version of {@code cls.getName()}
*
* @param cls the class for which to get the class name; may be null.
* @return the class name or the empty string in case the argument is {@code null}.
* @since 3.7
* @see Class#getSimpleName()
*/
public static String getName(final Class<?> cls) {
return getName(cls, StringUtils.EMPTY);
}
/**
* Null-safe version of {@code cls.getName()}
*
* @param cls the class for which to get the class name; may be null.
* @param valueIfNull the return value if the argument {@code cls} is {@code null}.
* @return the class name or {@code valueIfNull}
* @since 3.7
* @see Class#getName()
*/
public static String getName(final Class<?> cls, final String valueIfNull) {
return getName(cls, valueIfNull, false);
}
static String getName(final Class<?> cls, final String valueIfNull, final boolean simple) {
return cls == null ? valueIfNull : simple ? cls.getSimpleName() : cls.getName();
}
/**
* Null-safe version of {@code object.getClass().getName()}
*
* @param object the object for which to get the class name; may be null.
* @return the class name or the empty String.
* @since 3.7
* @see Class#getSimpleName()
*/
public static String getName(final Object object) {
return getName(object, StringUtils.EMPTY);
}
/**
* Null-safe version of {@code object.getClass().getSimpleName()}
*
* @param object the object for which to get the class name; may be null.
* @param valueIfNull the value to return if {@code object} is {@code null}.
* @return the class name or {@code valueIfNull}.
* @since 3.0
* @see Class#getName()
*/
public static String getName(final Object object, final String valueIfNull) {
return object == null ? valueIfNull : object.getClass().getName();
}
/**
* Gets the package name from the canonical name of a {@link Class}.
*
* @param cls the class to get the package name for, may be {@code null}.
* @return the package name or an empty string.
* @since 2.4
*/
public static String getPackageCanonicalName(final Class<?> cls) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getPackageCanonicalName(cls.getName());
}
/**
* Gets the package name from the class name of an {@link Object}.
*
* @param object the class to get the package name for, may be null.
* @param valueIfNull the value to return if null.
* @return the package name of the object, or the null value.
* @since 2.4
*/
public static String getPackageCanonicalName(final Object object, final String valueIfNull) {
if (object == null) {
return valueIfNull;
}
return getPackageCanonicalName(object.getClass().getName());
}
/**
* Gets the package name from the class name.
*
* <p>
* The string passed in is assumed to be a class name - it is not checked.
* </p>
* <p>
* If the class is in the default package, return an empty string.
* </p>
*
* @param name the name to get the package name for, may be {@code null}.
* @return the package name or an empty string.
* @since 2.4
*/
public static String getPackageCanonicalName(final String name) {
return getPackageName(getCanonicalName(name));
}
/**
* Gets the package name of a {@link Class}.
*
* @param cls the class to get the package name for, may be {@code null}.
* @return the package name or an empty string
*/
public static String getPackageName(final Class<?> cls) {
if (cls == null) {
return StringUtils.EMPTY;
}
return getPackageName(cls.getName());
}
/**
* Gets the package name of an {@link Object}.
*
* @param object the class to get the package name for, may be null.
* @param valueIfNull the value to return if null.
* @return the package name of the object, or the null value.
*/
public static String getPackageName(final Object object, final String valueIfNull) {
if (object == null) {
return valueIfNull;
}
return getPackageName(object.getClass());
}
/**
* Gets the package name from a {@link String}.
*
* <p>
* The string passed in is assumed to be a class name.
* </p>
* <p>
* If the class is unpackaged, return an empty string.
* </p>
*
* @param className the className to get the package name for, may be {@code null}.
* @return the package name or an empty string.
*/
public static String getPackageName(String className) {
if (StringUtils.isEmpty(className)) {
return StringUtils.EMPTY;
}
int i = 0;
// Strip array encoding
while (className.charAt(i) == '[') {
i++;
}
className = className.substring(i);
// Strip Object type encoding
if (className.charAt(0) == 'L' && className.charAt(className.length() - 1) == ';') {
className = className.substring(1);
}
i = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (i == -1) {
return StringUtils.EMPTY;
}
return className.substring(0, i);
}
/**
* Gets the primitive class for the given class name, for example "byte".
*
* @param className the primitive class for the given class name.
* @return the primitive class.
*/
static Class<?> getPrimitiveClass(final String className) {
return NAME_PRIMITIVE_MAP.get(className);
}
/**
* Gets the desired Method much like {@code Class.getMethod}, however it ensures that the returned Method is from a
* public class or interface and not from an anonymous inner class. This means that the Method is invokable and doesn't
* fall foul of Java bug (<a href="https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4071957">4071957</a>).
*
* <pre>
* {@code Set set = Collections.unmodifiableSet(...);
* Method method = ClassUtils.getPublicMethod(set.getClass(), "isEmpty", new Class[0]);
* Object result = method.invoke(set, new Object[]);}
* </pre>
*
* @param cls the class to check, not null.
* @param methodName the name of the method.
* @param parameterTypes the list of parameters.
* @return the method.
* @throws NullPointerException if the class is null.
* @throws SecurityException if a security violation occurred.
* @throws NoSuchMethodException if the method is not found in the given class or if the method doesn't conform with the
* requirements.
*/
public static Method getPublicMethod(final Class<?> cls, final String methodName, final Class<?>... parameterTypes) throws NoSuchMethodException {
final Method declaredMethod = cls.getMethod(methodName, parameterTypes);
if (isPublic(declaredMethod.getDeclaringClass())) {
return declaredMethod;
}
final List<Class<?>> candidateClasses = new ArrayList<>(getAllInterfaces(cls));
candidateClasses.addAll(getAllSuperclasses(cls));
for (final Class<?> candidateClass : candidateClasses) {
if (!isPublic(candidateClass)) {
continue;
}
final Method candidateMethod;
try {
candidateMethod = candidateClass.getMethod(methodName, parameterTypes);
} catch (final NoSuchMethodException ex) {
continue;
}
if (Modifier.isPublic(candidateMethod.getDeclaringClass().getModifiers())) {
return candidateMethod;
}
}
throw new NoSuchMethodException("Can't find a public method for " + methodName + " " + ArrayUtils.toString(parameterTypes));
}
/**
* Gets the canonical name minus the package name from a {@link Class}.
*
* @param cls the class for which to get the short canonical class name; may be null.
* @return the canonical name without the package name or an empty string.
* @since 2.4
* @see Class#getCanonicalName()
*/
public static String getShortCanonicalName(final Class<?> cls) {
return cls == null ? StringUtils.EMPTY : getShortCanonicalName(cls.getCanonicalName());
}
/**
* Gets the canonical name minus the package name for an {@link Object}.
*
* @param object the class to get the short name for, may be null.
* @param valueIfNull the value to return if null.
* @return the canonical name of the object without the package name, or the null value.
* @since 2.4
* @see Class#getCanonicalName()
*/
public static String getShortCanonicalName(final Object object, final String valueIfNull) {
return object == null ? valueIfNull : getShortCanonicalName(object.getClass());
}
/**
* Gets the canonical name minus the package name from a String.
*
* <p>
* The string passed in is assumed to be a class name - it is not checked.
* </p>
*
* <p>
* Note that this method is mainly designed to handle the arrays and primitives properly. If the class is an inner class
* then the result value will not contain the outer classes. This way the behavior of this method is different from
* {@link #getShortClassName(String)}. The argument in that case is class name and not canonical name and the return
* value retains the outer classes.
* </p>
*
* <p>
* Note that there is no way to reliably identify the part of the string representing the package hierarchy and the part
* that is the outer class or classes in case of an inner class. Trying to find the class would require reflective call
* and the class itself may not even be on the class path. Relying on the fact that class names start with capital
* letter and packages with lower case is heuristic.
* </p>
*
* <p>
* It is recommended to use {@link #getShortClassName(String)} for cases when the class is an inner class and use this
* method for cases it is designed for.
* </p>
*
* <table>
* <caption>Examples</caption>
* <tr>
* <td>return value</td>
* <td>input</td>
* </tr>
* <tr>
* <td>{@code ""}</td>
* <td>{@code (String) null}</td>
* </tr>
* <tr>
* <td>{@code "Map.Entry"}</td>
* <td>{@code java.util.Map.Entry.class.getName()}</td>
* </tr>
* <tr>
* <td>{@code "Entry"}</td>
* <td>{@code java.util.Map.Entry.class.getCanonicalName()}</td>
* </tr>
* <tr>
* <td>{@code "ClassUtils"}</td>
* <td>{@code "org.apache.commons.lang3.ClassUtils"}</td>
* </tr>
* <tr>
* <td>{@code "ClassUtils[]"}</td>
* <td>{@code "[Lorg.apache.commons.lang3.ClassUtils;"}</td>
* </tr>
* <tr>
* <td>{@code "ClassUtils[][]"}</td>
* <td>{@code "[[Lorg.apache.commons.lang3.ClassUtils;"}</td>
* </tr>
* <tr>
* <td>{@code "ClassUtils[]"}</td>
* <td>{@code "org.apache.commons.lang3.ClassUtils[]"}</td>
* </tr>
* <tr>
* <td>{@code "ClassUtils[][]"}</td>
* <td>{@code "org.apache.commons.lang3.ClassUtils[][]"}</td>
* </tr>
* <tr>
* <td>{@code "int[]"}</td>
* <td>{@code "[I"}</td>
* </tr>
* <tr>
* <td>{@code "int[]"}</td>
* <td>{@code int[].class.getCanonicalName()}</td>
* </tr>
* <tr>
* <td>{@code "int[]"}</td>
* <td>{@code int[].class.getName()}</td>
* </tr>
* <tr>
* <td>{@code "int[][]"}</td>
* <td>{@code "[[I"}</td>
* </tr>
* <tr>
* <td>{@code "int[]"}</td>
* <td>{@code "int[]"}</td>
* </tr>
* <tr>
* <td>{@code "int[][]"}</td>