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Open source Reference Implementation of JSR-67: SOAP with Attachments API for Java (SAAJ MR: 1.4)
There is a newer version: 3.0.4
/*
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 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * http://glassfish.java.net/public/CDDL+GPL_1_1.html
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package com.sun.xml.messaging.saaj.soap;

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;
                    }
                });
    }
}