1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.id.uuid.state;
19
20 import java.io.File;
21 import java.io.FileWriter;
22 import java.io.IOException;
23 import java.net.URL;
24 import java.util.Iterator;
25 import java.util.Set;
26
27 /**
28 * <p>The <code>ReadWriteFileStateImpl</code> is an implementation of the
29 * <code>State</code> interface. This implementation provides better guarantees
30 * that no duplicate UUID's will be generated since the last time stamp, and
31 * last clock sequence are stored to a persistent file.
32 *
33 * @author Commons-Id team
34 * @version $Id: ReadWriteFileStateImpl.java 480488 2006-11-29 08:57:26Z bayard $
35 */
36 public class ReadWriteFileStateImpl extends ReadOnlyResourceStateImpl implements State {
37
38 /**
39 * Persists the UUID generator state to file.
40 *
41 * @see org.apache.commons.id.uuid.state.State#store(java.util.Set)
42 */
43 public void store(Set nodes) throws IOException {
44 writeXML(genXML(nodes));
45 }
46
47 /**
48 * Returns an XML string of the node Set.
49 *
50 * @param nodes the Set to create xml for.
51 * @return an XML string of the node Set.
52 * @throws IOException an IOException.
53 */
54 private String genXML(Set nodes) throws IOException {
55 Iterator it = nodes.iterator();
56 StringBuffer buf = new StringBuffer(1024);
57 buf.append(StateHelper.XML_DOC_START);
58 buf.append(getSynchInterval());
59 buf.append(StateHelper.XML_DOC_START_END);
60 while (it.hasNext()) {
61 Node n = (Node) it.next();
62 buf.append(StateHelper.XML_NODE_TAG_START);
63 buf.append(StateHelper.encodeMACAddress(n.getNodeIdentifier()));
64 buf.append(StateHelper.XML_NODE_TAG_AFTER_ID);
65 buf.append(n.getClockSequence());
66 buf.append(StateHelper.XML_NODE_TAG_AFTER_CSEQ);
67 buf.append(n.getLastTimestamp());
68 buf.append(StateHelper.XML_NODE_TAG_END);
69 }
70 buf.append(StateHelper.XML_DOC_END);
71 return buf.toString();
72 }
73
74 /**
75 * Returns an XML string of the node Set using a predetermined last time stamp for all <code>Node</code>s.
76 *
77 * @param nodes the Set to create xml for.
78 * @param timestamp the timestamp to write for all nodes.
79 * @return an XML string of the node Set.
80 * @throws IOException an IOException.
81 */
82 private String genXML(Set nodes, long timestamp) throws IOException {
83 Iterator it = nodes.iterator();
84 StringBuffer buf = new StringBuffer(1024);
85 buf.append(StateHelper.XML_DOC_START);
86 buf.append(getSynchInterval());
87 buf.append(StateHelper.XML_DOC_START_END);
88 while (it.hasNext()) {
89 Node n = (Node) it.next();
90 buf.append(StateHelper.XML_NODE_TAG_START);
91 buf.append(StateHelper.encodeMACAddress(n.getNodeIdentifier()));
92 buf.append(StateHelper.XML_NODE_TAG_AFTER_ID);
93 buf.append(n.getClockSequence());
94 buf.append(StateHelper.XML_NODE_TAG_AFTER_CSEQ);
95 buf.append(timestamp);
96 buf.append(StateHelper.XML_NODE_TAG_END);
97 }
98 buf.append(StateHelper.XML_DOC_END);
99 return buf.toString();
100 }
101
102 /**
103 * <p>Writes the XML String to the file system.</p>
104 *
105 * @param xml the xml string to write.
106 */
107 private void writeXML(String xml) {
108 String resourceName = System.getProperty(CONFIG_FILENAME_KEY);
109 if (resourceName == null) {
110 return;
111 } else {
112 URL rUrl = ClassLoader.getSystemResource(resourceName);
113 if (rUrl != null) {
114 File file = new File(rUrl.getFile());
115 if (file != null && file.canWrite()) {
116 FileWriter fw = null;
117 try {
118 fw = new FileWriter(file);
119 fw.write(xml);
120 fw.close();
121 } catch (IOException ioe) {
122 //@TODO log it?
123 } finally {
124 try {
125 fw.close();
126 } catch (IOException ioee) {
127 ; //Nothing to do.
128 }
129 fw = null;
130 file = null;
131 }
132 }
133 }
134 }
135 }
136 }