01: /*
02: *
03: *
04: * Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
05: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License version
09: * 2 only, as published by the Free Software Foundation.
10: *
11: * This program is distributed in the hope that it will be useful, but
12: * WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14: * General Public License version 2 for more details (a copy is
15: * included at /legal/license.txt).
16: *
17: * You should have received a copy of the GNU General Public License
18: * version 2 along with this work; if not, write to the Free Software
19: * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20: * 02110-1301 USA
21: *
22: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
23: * Clara, CA 95054 or visit www.sun.com if you need additional
24: * information or have any questions.
25: */
26:
27: package com.sun.midp.suspend;
28:
29: import com.sun.midp.security.SecurityToken;
30: import com.sun.midp.security.Permissions;
31:
32: import java.io.IOException;
33:
34: /**
35: * Processes suspend/resume requests for networking resources.
36: */
37: public class NetworkSubsystem extends AbstractSubsystem {
38: /** The only instance of the subsytem. */
39: private static NetworkSubsystem instance = new NetworkSubsystem();
40:
41: /**
42: * Constructs an instance in registers it in the suspend system.
43: */
44: private NetworkSubsystem() {
45: state = ACTIVE;
46: SuspendSystem.getInstance(classSecurityToken)
47: .registerSubsystem(this );
48: }
49:
50: /**
51: * Returns te only instance.
52: * @return the singleton instance
53: * @param token security token that identifies caller access rights
54: */
55: public static NetworkSubsystem getInstance(SecurityToken token) {
56: token.checkIfPermissionAllowed(Permissions.MIDP);
57: return instance;
58: }
59:
60: /**
61: * Checks that networking subsystem is in either active or resuming
62: * state and throws <code>IOException</code> if it is not.
63: * @throws IOException if the networking subsystem state is neither
64: * <code>ACTIVE</code> nor <code>RESUMING</code>.
65: */
66: public synchronized void ensureActive() throws IOException {
67: if (state != ACTIVE && state != RESUMING) {
68: throw new IOException("Networking is not active");
69: }
70: }
71: }
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