org.apache.commons.id.uuid.state.ReadWriteFileStateImpl Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.id.uuid.state;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URL;
import java.util.Iterator;
import java.util.Set;
/**
* The ReadWriteFileStateImpl is an implementation of the
* State interface. This implementation provides better guarantees
* that no duplicate UUID's will be generated since the last time stamp, and
* last clock sequence are stored to a persistent file.
*
* @author Commons-Id team
* @version $Id: ReadWriteFileStateImpl.java 480488 2006-11-29 08:57:26Z bayard $
*/
public class ReadWriteFileStateImpl extends ReadOnlyResourceStateImpl implements State {
/**
* Persists the UUID generator state to file.
*
* @see org.apache.commons.id.uuid.state.State#store(java.util.Set)
*/
public void store(Set nodes) throws IOException {
writeXML(genXML(nodes));
}
/**
* Returns an XML string of the node Set.
*
* @param nodes the Set to create xml for.
* @return an XML string of the node Set.
* @throws IOException an IOException.
*/
private String genXML(Set nodes) throws IOException {
Iterator it = nodes.iterator();
StringBuffer buf = new StringBuffer(1024);
buf.append(StateHelper.XML_DOC_START);
buf.append(getSynchInterval());
buf.append(StateHelper.XML_DOC_START_END);
while (it.hasNext()) {
Node n = (Node) it.next();
buf.append(StateHelper.XML_NODE_TAG_START);
buf.append(StateHelper.encodeMACAddress(n.getNodeIdentifier()));
buf.append(StateHelper.XML_NODE_TAG_AFTER_ID);
buf.append(n.getClockSequence());
buf.append(StateHelper.XML_NODE_TAG_AFTER_CSEQ);
buf.append(n.getLastTimestamp());
buf.append(StateHelper.XML_NODE_TAG_END);
}
buf.append(StateHelper.XML_DOC_END);
return buf.toString();
}
/**
* Returns an XML string of the node Set using a predetermined last time stamp for all Nodes.
*
* @param nodes the Set to create xml for.
* @param timestamp the timestamp to write for all nodes.
* @return an XML string of the node Set.
* @throws IOException an IOException.
*/
private String genXML(Set nodes, long timestamp) throws IOException {
Iterator it = nodes.iterator();
StringBuffer buf = new StringBuffer(1024);
buf.append(StateHelper.XML_DOC_START);
buf.append(getSynchInterval());
buf.append(StateHelper.XML_DOC_START_END);
while (it.hasNext()) {
Node n = (Node) it.next();
buf.append(StateHelper.XML_NODE_TAG_START);
buf.append(StateHelper.encodeMACAddress(n.getNodeIdentifier()));
buf.append(StateHelper.XML_NODE_TAG_AFTER_ID);
buf.append(n.getClockSequence());
buf.append(StateHelper.XML_NODE_TAG_AFTER_CSEQ);
buf.append(timestamp);
buf.append(StateHelper.XML_NODE_TAG_END);
}
buf.append(StateHelper.XML_DOC_END);
return buf.toString();
}
/**
*
Writes the XML String to the file system.
*
* @param xml the xml string to write.
*/
private void writeXML(String xml) {
String resourceName = System.getProperty(CONFIG_FILENAME_KEY);
if (resourceName == null) {
return;
} else {
URL rUrl = ClassLoader.getSystemResource(resourceName);
if (rUrl != null) {
File file = new File(rUrl.getFile());
if (file != null && file.canWrite()) {
FileWriter fw = null;
try {
fw = new FileWriter(file);
fw.write(xml);
fw.close();
} catch (IOException ioe) {
//@TODO log it?
} finally {
try {
fw.close();
} catch (IOException ioee) {
; //Nothing to do.
}
fw = null;
file = null;
}
}
}
}
}
}