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/*
* Copyright 2002-2014 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 spark.utils;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Miscellaneous class utility methods.
* Mainly for internal use within the framework.
*
* @author Juergen Hoeller
* @author Keith Donald
* @author Rob Harrop
* @author Sam Brannen
* @since 1.1
*
* Code copied from Spring source. Modifications made (mostly removal of methods) by Per Wendel.
*
*/
public abstract class ClassUtils {
/**
* Suffix for array class names: "[]"
*/
public static final String ARRAY_SUFFIX = "[]";
/**
* Prefix for internal array class names: "["
*/
private static final String INTERNAL_ARRAY_PREFIX = "[";
/**
* Prefix for internal non-primitive array class names: "[L"
*/
private static final String NON_PRIMITIVE_ARRAY_PREFIX = "[L";
/**
* Map with primitive wrapper type as key and corresponding primitive
* type as value, for example: Integer.class -> int.class.
*/
private static final Map, Class> primitiveWrapperTypeMap = new HashMap<>(8);
/**
* Map with primitive type as key and corresponding wrapper
* type as value, for example: int.class -> Integer.class.
*/
private static final Map, Class> primitiveTypeToWrapperMap = 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<>(32);
/**
* Map with common "java.lang" class name as key and corresponding Class as value.
* Primarily for efficient deserialization of remote invocations.
*/
private static final Map> commonClassCache = new HashMap<>(32);
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 (Map.Entry, Class> entry : primitiveWrapperTypeMap.entrySet()) {
primitiveTypeToWrapperMap.put(entry.getValue(), entry.getKey());
registerCommonClasses(entry.getKey());
}
Set> primitiveTypes = new HashSet<>(32);
primitiveTypes.addAll(primitiveWrapperTypeMap.values());
primitiveTypes.addAll(Arrays.asList(new Class[] {
boolean[].class, byte[].class, char[].class, double[].class,
float[].class, int[].class, long[].class, short[].class}));
primitiveTypes.add(void.class);
for (Class primitiveType : primitiveTypes) {
primitiveTypeNameMap.put(primitiveType.getName(), primitiveType);
}
registerCommonClasses(Boolean[].class, Byte[].class, Character[].class, Double[].class,
Float[].class, Integer[].class, Long[].class, Short[].class);
registerCommonClasses(Number.class, Number[].class, String.class, String[].class,
Object.class, Object[].class, Class.class, Class[].class);
registerCommonClasses(Throwable.class, Exception.class, RuntimeException.class,
Error.class, StackTraceElement.class, StackTraceElement[].class);
}
/**
* Register the given common classes with the ClassUtils cache.
*/
private static void registerCommonClasses(Class... commonClasses) {
for (Class clazz : commonClasses) {
commonClassCache.put(clazz.getName(), clazz);
}
}
/**
* 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
* {@code Class.forName}, which accepts a {@code null} ClassLoader
* reference as well).
*
* @return the default ClassLoader (never {@code null})
* @see Thread#getContextClassLoader()
*/
public static ClassLoader getDefaultClassLoader() {
ClassLoader cl = null;
try {
cl = Thread.currentThread().getContextClassLoader();
} catch (Throwable ex) {
// Cannot access thread context ClassLoader - falling back to system class loader...
}
if (cl == null) {
// No thread context class loader -> use class loader of this class.
cl = ClassUtils.class.getClassLoader();
}
return cl;
}
/**
* Replacement for {@code Class.forName()} that also returns Class instances
* for primitives (e.g."int") and array class names (e.g. "String[]").
* Furthermore, it is also capable of resolving inner class names in Java source
* style (e.g. "java.lang.Thread.State" instead of "java.lang.Thread$State").
*
* @param name the name of the Class
* @param classLoader the class loader to use
* (may be {@code null}, which indicates the default class loader)
* @return Class instance for the supplied name
* @throws ClassNotFoundException if the class was not found
* @throws LinkageError if the class file could not be loaded
* @see Class#forName(String, boolean, ClassLoader)
*/
public static Class forName(String name, ClassLoader classLoader) throws ClassNotFoundException, LinkageError {
Assert.notNull(name, "Name must not be null");
Class clazz = resolvePrimitiveClassName(name);
if (clazz == null) {
clazz = commonClassCache.get(name);
}
if (clazz != null) {
return clazz;
}
// "java.lang.String[]" style arrays
if (name.endsWith(ARRAY_SUFFIX)) {
String elementClassName = name.substring(0, name.length() - ARRAY_SUFFIX.length());
Class elementClass = forName(elementClassName, classLoader);
return Array.newInstance(elementClass, 0).getClass();
}
// "[Ljava.lang.String;" style arrays
if (name.startsWith(NON_PRIMITIVE_ARRAY_PREFIX) && name.endsWith(";")) {
String elementName = name.substring(NON_PRIMITIVE_ARRAY_PREFIX.length(), name.length() - 1);
Class elementClass = forName(elementName, classLoader);
return Array.newInstance(elementClass, 0).getClass();
}
// "[[I" or "[[Ljava.lang.String;" style arrays
if (name.startsWith(INTERNAL_ARRAY_PREFIX)) {
String elementName = name.substring(INTERNAL_ARRAY_PREFIX.length());
Class elementClass = forName(elementName, classLoader);
return Array.newInstance(elementClass, 0).getClass();
}
ClassLoader classLoaderToUse = classLoader;
if (classLoaderToUse == null) {
classLoaderToUse = getDefaultClassLoader();
}
try {
return classLoaderToUse.loadClass(name);
} catch (ClassNotFoundException ex) {
int lastDotIndex = name.lastIndexOf('.');
if (lastDotIndex != -1) {
String innerClassName = name.substring(0, lastDotIndex) + '$' + name.substring(lastDotIndex + 1);
try {
return classLoaderToUse.loadClass(innerClassName);
} catch (ClassNotFoundException ex2) {
// swallow - let original exception get through
}
}
throw ex;
}
}
/**
* Resolve the given class name as primitive class, if appropriate,
* according to the JVM's naming rules for primitive classes.
*
Also supports the JVM's internal class names for primitive arrays.
* Does not support the "[]" suffix notation for primitive arrays;
* this is only supported by {@link #forName(String, ClassLoader)}.
*
* @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 = primitiveTypeNameMap.get(name);
}
return result;
}
/**
* 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('.', '/');
}
}