Thu, 31 Aug 2017 15:18:52 +0800
merge
1 /*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
26 package com.sun.xml.internal.xsom.util;
28 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30 import java.text.MessageFormat;
31 import java.util.ResourceBundle;
32 import java.util.WeakHashMap;
34 /**
35 * Simple utility ensuring that the value is cached only in case it is non-internal implementation
36 */
37 abstract class ContextClassloaderLocal<V> {
39 private static final String FAILED_TO_CREATE_NEW_INSTANCE = "FAILED_TO_CREATE_NEW_INSTANCE";
41 private WeakHashMap<ClassLoader, V> CACHE = new WeakHashMap<ClassLoader, V>();
43 public V get() throws Error {
44 ClassLoader tccl = getContextClassLoader();
45 V instance = CACHE.get(tccl);
46 if (instance == null) {
47 instance = createNewInstance();
48 CACHE.put(tccl, instance);
49 }
50 return instance;
51 }
53 public void set(V instance) {
54 CACHE.put(getContextClassLoader(), instance);
55 }
57 protected abstract V initialValue() throws Exception;
59 private V createNewInstance() {
60 try {
61 return initialValue();
62 } catch (Exception e) {
63 throw new Error(format(FAILED_TO_CREATE_NEW_INSTANCE, getClass().getName()), e);
64 }
65 }
67 private static String format(String property, Object... args) {
68 String text = ResourceBundle.getBundle(ContextClassloaderLocal.class.getName()).getString(property);
69 return MessageFormat.format(text, args);
70 }
72 private static ClassLoader getContextClassLoader() {
73 return (ClassLoader)
74 AccessController.doPrivileged(new PrivilegedAction() {
75 public Object run() {
76 ClassLoader cl = null;
77 try {
78 cl = Thread.currentThread().getContextClassLoader();
79 } catch (SecurityException ex) {
80 }
81 return cl;
82 }
83 });
84 }
85 }