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/*
 * Copyright (c) 1997, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package javax.mail.internet;

import java.net.*;
import java.util.concurrent.atomic.AtomicInteger;
import javax.mail.Session;

/**
 * This is a utility class that generates unique values. The generated
 * String contains only US-ASCII characters and hence is safe for use
 * in RFC822 headers. 

* * This is a package private class. * * @author John Mani * @author Max Spivak * @author Bill Shannon */ class UniqueValue { /** * A global unique number, to ensure uniqueness of generated strings. */ private static AtomicInteger id = new AtomicInteger(); /** * Get a unique value for use in a multipart boundary string. * * This implementation generates it by concatenating a global * part number, a newly created object's hashCode(), * and the current time (in milliseconds). */ public static String getUniqueBoundaryValue() { StringBuilder s = new StringBuilder(); long hash = s.hashCode(); // Unique string is ----=_Part__. s.append("----=_Part_").append(id.getAndIncrement()).append("_"). append(hash).append('.'). append(System.currentTimeMillis()); return s.toString(); } /** * Get a unique value for use in a Message-ID. * * This implementation generates it by concatenating a newly * created object's hashCode(), a global ID * (incremented on every use), the current time (in milliseconds), * and the host name from this user's local address generated by * InternetAddress.getLocalAddress(). * (The host name defaults to "localhost" if * getLocalAddress() returns null.) * * @param ssn Session object used to get the local address * @see javax.mail.internet.InternetAddress */ public static String getUniqueMessageIDValue(Session ssn) { String suffix = null; InternetAddress addr = InternetAddress.getLocalAddress(ssn); if (addr != null) suffix = addr.getAddress(); else { suffix = "jakartamailuser@localhost"; // worst-case default } int at = suffix.lastIndexOf('@'); if (at >= 0) suffix = suffix.substring(at); StringBuilder s = new StringBuilder(); // Unique string is .. s.append(s.hashCode()).append('.'). append(id.getAndIncrement()).append('.'). append(System.currentTimeMillis()). append(suffix); return s.toString(); } }





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