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/*
* Copyright 2002-2020 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
*
* 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 com.feilong.lib.springframework.util;
/**
* Miscellaneous {@code java.lang.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
*/
public abstract class ClassUtils{
/** The package separator character: '.' */
private static final char PACKAGE_SEPARATOR = '.';
/** The path separator character: '/' */
private static final char PATH_SEPARATOR = '/';
/**
* 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 clearly prefer 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 (only {@code null} if even the system
* ClassLoader isn't accessible)
* @see Thread#getContextClassLoader()
* @see ClassLoader#getSystemClassLoader()
*/
public static ClassLoader getDefaultClassLoader(){
ClassLoader cl = null;
try{
cl = Thread.currentThread().getContextClassLoader();
}catch (Throwable ex){
// Cannot access thread context ClassLoader - falling back...
}
if (cl == null){
// No thread context class loader -> use class loader of this class.
cl = ClassUtils.class.getClassLoader();
if (cl == null){
// getClassLoader() returning null indicates the bootstrap ClassLoader
try{
cl = ClassLoader.getSystemClassLoader();
}catch (Throwable ex){
// Cannot access system ClassLoader - oh well, maybe the caller can live with null...
}
}
}
return cl;
}
/**
* 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(PACKAGE_SEPARATOR);
if (packageEndIndex == -1){
return "";
}
String packageName = className.substring(0, packageEndIndex);
return packageName.replace(PACKAGE_SEPARATOR, PATH_SEPARATOR);
}
}