/*
* Copyright 2010-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Portions copyright 2006-2009 James Murty. Please see LICENSE.txt
* for applicable license terms and NOTICE.txt for applicable notices.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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.amazonaws.util;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.jar.JarFile;
/**
* Classes related utilities.
*/
public enum Classes {
;
/**
* Returns the class of the immediate subclass of the given parent class for
* the given object instance; or null if such immediate subclass cannot be
* uniquely identified for the given object instance.
*
* @param parentClass the parent class. The child class is {@link Object} if
* and only if the parent class is null.
* @param instance the given object instance
*/
public static Class<?> childClassOf(Class<?> parentClass,
Object instance) {
if (instance == null || instance == Object.class)
return null;
if (parentClass != null) {
if (parentClass.isInterface()) {
// child of an interface class is not injective (ie one-to-one)
return null;
}
}
Class<?> childClass = instance.getClass();
while (true) {
Class<?> parent = childClass.getSuperclass();
if (parent == parentClass)
return childClass;
if (parent == null)
return null;
childClass = parent;
}
}
/**
* Returns the jar file from which the given class is loaded; or null if no
* such jar file can be located.
*/
public static JarFile jarFileOf(Class<?> klass) {
URL url = klass.getResource(
"/" + klass.getName().replace('.', '/') + ".class");
if (url == null)
return null;
String s = url.getFile();
int beginIndex = s.indexOf("file:") + "file:".length();
int endIndex = s.indexOf(".jar!");
if (endIndex == -1)
return null;
endIndex += ".jar".length();
String f = s.substring(beginIndex, endIndex);
File file = new File(f);
try {
return file.exists() ? new JarFile(file) : null;
} catch (IOException e) {
throw new IllegalStateException(e);
}
}
}