com.sun.xml.xsom.util.ContextClassloaderLocal Maven / Gradle / Ivy
/*
* Copyright (c) 2014, 2022 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package com.sun.xml.xsom.util;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.MessageFormat;
import java.util.ResourceBundle;
import java.util.WeakHashMap;
/**
* Simple utility ensuring that the value is cached only in case it is non-internal implementation
*/
abstract class ContextClassloaderLocal {
private static final String FAILED_TO_CREATE_NEW_INSTANCE = "FAILED_TO_CREATE_NEW_INSTANCE";
private WeakHashMap CACHE = new WeakHashMap<>();
public V get() throws Error {
ClassLoader tccl = getContextClassLoader();
V instance = CACHE.get(tccl);
if (instance == null) {
instance = createNewInstance();
CACHE.put(tccl, instance);
}
return instance;
}
public void set(V instance) {
CACHE.put(getContextClassLoader(), instance);
}
protected abstract V initialValue() throws Exception;
private V createNewInstance() {
try {
return initialValue();
} catch (Exception e) {
throw new Error(format(FAILED_TO_CREATE_NEW_INSTANCE, getClass().getName()), e);
}
}
private static String format(String property, Object... args) {
String text = ResourceBundle.getBundle(ContextClassloaderLocal.class.getName()).getString(property);
return MessageFormat.format(text, args);
}
private static ClassLoader getContextClassLoader() {
return AccessController.doPrivileged(new PrivilegedAction() {
public ClassLoader run() {
ClassLoader cl = null;
try {
cl = Thread.currentThread().getContextClassLoader();
} catch (SecurityException ex) {
}
return cl;
}
});
}
}