1 /*
2 * Copyright 1999-2004 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.naming;
27
28 /**
29 * This class represents a Reference whose contents is a name, called the link name,
30 * that is bound to an atomic name in a context.
31 *<p>
32 * The name is a URL, or a name to be resolved relative to the initial
33 * context, or if the first character of the name is ".", the name
34 * is relative to the context in which the link is bound.
35 *<p>
36 * Normal resolution of names in context operations always follow links.
37 * Resolution of the link name itself may cause resolution to pass through
38 * other links. This gives rise to the possibility of a cycle of links whose
39 * resolution could not terminate normally. As a simple means to avoid such
40 * non-terminating resolutions, service providers may define limits on the
41 * number of links that may be involved in any single operation invoked
42 * by the caller.
43 *<p>
44 * A LinkRef contains a single StringRefAddr, whose type is "LinkAddress",
45 * and whose contents is the link name. The class name field of the
46 * Reference is that of this (LinkRef) class.
47 *<p>
48 * LinkRef is bound to a name using the normal Context.bind()/rebind(), and
49 * DirContext.bind()/rebind(). Context.lookupLink() is used to retrieve the link
50 * itself if the terminal atomic name is bound to a link.
51 *<p>
52 * Many naming systems support a native notion of link that may be used
53 * within the naming system itself. JNDI does not specify whether
54 * there is any relationship between such native links and JNDI links.
55 *<p>
56 * A LinkRef instance is not synchronized against concurrent access by multiple
57 * threads. Threads that need to access a LinkRef instance concurrently should
58 * synchronize amongst themselves and provide the necessary locking.
59 *
60 * @author Rosanna Lee
61 * @author Scott Seligman
62 *
63 * @see LinkException
64 * @see LinkLoopException
65 * @see MalformedLinkException
66 * @see Context#lookupLink
67 * @since 1.3
68 */
69
70 /*<p>
71 * The serialized form of a LinkRef object consists of the serialized
72 * fields of its Reference superclass.
73 */
74
75 public class LinkRef extends Reference {
76 /* code for link handling */
77 static final String linkClassName = LinkRef.class.getName();
78 static final String linkAddrType = "LinkAddress";
79
80 /**
81 * Constructs a LinkRef for a name.
82 * @param linkName The non-null name for which to create this link.
83 */
84 public LinkRef(Name linkName) {
85 super(linkClassName, new StringRefAddr(linkAddrType, linkName.toString()));
86 }
87
88 /**
89 * Constructs a LinkRef for a string name.
90 * @param linkName The non-null name for which to create this link.
91 */
92 public LinkRef(String linkName) {
93 super(linkClassName, new StringRefAddr(linkAddrType, linkName));
94 }
95
96 /**
97 * Retrieves the name of this link.
98 *
99 * @return The non-null name of this link.
100 * @exception MalformedLinkException If a link name could not be extracted
101 * @exception NamingException If a naming exception was encountered.
102 */
103 public String getLinkName() throws NamingException {
104 if (className != null && className.equals(linkClassName)) {
105 RefAddr addr = get(linkAddrType);
106 if (addr != null && addr instanceof StringRefAddr) {
107 return (String)((StringRefAddr)addr).getContent();
108 }
109 }
110 throw new MalformedLinkException();
111 }
112 /**
113 * Use serialVersionUID from JNDI 1.1.1 for interoperability
114 */
115 private static final long serialVersionUID = -5386290613498931298L;
116 }
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