git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@1591 6c8d7289-2bf4-0310-a012-ef5d649a1542pull/1/head
orbiter
19 years ago
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// kelondroXMLTables.java
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// -------------------------
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// part of The Kelondro Database
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// (C) by Michael Peter Christen; mc@anomic.de
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2006
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// created 09.02.2006
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//
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// $LastChangedDate: 2005-09-22 22:01:26 +0200 (Thu, 22 Sep 2005) $
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// $LastChangedRevision: 774 $
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// $LastChangedBy: orbiter $
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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// Using this software in any meaning (reading, learning, copying, compiling,
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// running) means that you agree that the Author(s) is (are) not responsible
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// for cost, loss of data or any harm that may be caused directly or indirectly
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// by usage of this softare or this documentation. The usage of this software
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// is on your own risk. The installation and usage (starting/running) of this
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// software may allow other people or application to access your computer and
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// any attached devices and is highly dependent on the configuration of the
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// software which must be done by the user of the software; the author(s) is
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// (are) also not responsible for proper configuration and usage of the
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// software, even if provoked by documentation provided together with
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// the software.
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//
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// Any changes to this file according to the GPL as documented in the file
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// gpl.txt aside this file in the shipment you received can be done to the
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// lines that follows this copyright notice here, but changes must not be
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// done inside the copyright notive above. A re-distribution must contain
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// the intact and unchanged copyright notice.
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// Contributions and changes to the program code must be marked as such.
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package de.anomic.kelondro;
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import java.beans.*;
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import java.io.*;
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import java.util.*;
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public class kelondroXMLTables {
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private Hashtable tables;
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// tables is a hashtable that contains hashtables as values in the table
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private File propFile;
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private long timestamp;
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public kelondroXMLTables() {
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this.propFile = null;
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this.timestamp = System.currentTimeMillis();
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this.tables = new Hashtable();
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}
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public kelondroXMLTables(File file) throws IOException {
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this.propFile = file;
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this.timestamp = System.currentTimeMillis();
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if (propFile.exists()) {
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XMLDecoder xmldec = new XMLDecoder(new FileInputStream(propFile));
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tables = (Hashtable) xmldec.readObject();
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xmldec.close();
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} else {
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tables = new Hashtable();
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}
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}
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public void commit(File target) throws IOException {
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// this method is used if the Mircrotable was created without assigning
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// a file to it as an empty table the table then becomes file-based,
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// and write operation will be committed to the file
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this.propFile = target;
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commit(true);
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}
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private void commit(boolean force) throws IOException {
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// this function commits the data to a file
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// it does not save the data until a specific waiting-time has been lasted
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if ((force) || (System.currentTimeMillis() - timestamp > 10000)) {
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// check error case: can only occur if logical programmic error
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// exists
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if (this.propFile == null)
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throw new RuntimeException("Microtables.commit: no file specified");
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// write first to a temporary file
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File tmpFile = new File(this.propFile.toString() + ".tmp");
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// write file
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XMLEncoder xmlenc = new XMLEncoder(new FileOutputStream(tmpFile));
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xmlenc.writeObject(tables);
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xmlenc.close();
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// delete old file and rename tmp-file to old file's name
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this.propFile.delete();
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tmpFile.renameTo(this.propFile);
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// set the new time stamp
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timestamp = System.currentTimeMillis();
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}
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}
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public boolean hasTable(String table) {
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return (tables.get(table) != null);
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}
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public int sizeTable(String table) {
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// returns number of entries in table; if table does not exist -1
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Hashtable l = (Hashtable) tables.get(table);
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if (l == null)
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return -1;
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return l.size();
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}
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public void createTable(String table) throws IOException {
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// creates a new table
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Hashtable l = (Hashtable) tables.get(table);
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if (l != null)
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return; // we do not overwite
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tables.put(table, new Hashtable());
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if (this.propFile != null)
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commit(false);
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}
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public void set(String table, String key, String value) throws IOException {
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if (table != null) {
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Hashtable l = (Hashtable) tables.get(table);
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if (l == null)
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throw new RuntimeException("Microtables.set: table does not exist");
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if (value == null)
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value = "";
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l.put(key, value);
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}
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if (this.propFile != null)
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commit(false);
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}
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public String get(String table, String key, String deflt) {
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if (table != null) {
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Hashtable l = (Hashtable) tables.get(table);
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if (l == null)
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throw new RuntimeException("Microtables.get: table does not exist");
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if (l.containsKey(key))
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return (String) l.get(key);
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else
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return deflt;
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}
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return null;
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}
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public boolean has(String table, String key) {
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if (table != null) {
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Hashtable l = (Hashtable) tables.get(table);
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if (l == null)
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throw new RuntimeException("Microtables.has: table does not exist");
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return (l.containsKey(key));
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}
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return false;
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}
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public Enumeration keys(String table) {
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if (table != null) {
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Hashtable l = (Hashtable) tables.get(table);
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if (l == null)
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throw new RuntimeException("Microtables.keys: table does not exist");
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return l.keys();
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}
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return null;
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}
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public void close() throws IOException {
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finalize();
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}
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// we finalize the operation by saving everything throug the scheduler
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// this method is called by the java GC bevore it destroys the object
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protected void finalize() throws IOException {
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commit(true);
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}
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}
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