/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.data.shapefile.indexed.attribute;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.channels.FileChannel;
import java.text.DecimalFormat;
import org.geotools.data.DataUtilities;
/**
* <P>
* Class to manage a summary for attribute indexes.
* </P>
* <P>
* It's just map that associates attribute name with index file. Using the name
* instead of its position on dbf permits to abstract from position, so
* attribute order can change with no influence on indexes.
* </P>
*
* @author Manuele Ventoruzzo
*
*
* @source $URL$
*/
public class AttributeIndexSummary {
public static final String SUMMARY_EXT = ".ids";
public static final String INDEX_EXT = ".i";
public static final DecimalFormat SUFFIX = new DecimalFormat("00");
public static final int DEFAULT_CACHE_SIZE = 134217728; // 128MB
/** Url of summary file */
protected URL summaryURL = null;
protected String filename = null;
protected int cacheSize;
/**
* Creates an IndexSummary
*
* @param shapefileUrl
* url of shapefile for wich indexes are related to
*/
public AttributeIndexSummary(URL shpURL) throws MalformedURLException, IOException {
this(shpURL,DEFAULT_CACHE_SIZE);
}
/**
* Creates an IndexSummary
*
* @param shapefileUrl
* url of shapefile for wich indexes are related to
* @param cacheSize
* maximum amount of memory to be used for index creation
*/
public AttributeIndexSummary(URL shpURL, int cacheSize) throws MalformedURLException, IOException {
try {
filename = java.net.URLDecoder.decode(shpURL.toString(),
"US-ASCII");
filename = filename.substring(0, filename.lastIndexOf(".shp"));
} catch (java.io.UnsupportedEncodingException use) {
throw new java.net.MalformedURLException("Unable to decode " + shpURL + " cause " + use.getMessage());
}
int indexslash = filename.lastIndexOf(File.pathSeparator);
if (indexslash == -1) {
indexslash = 0;
}
summaryURL = new URL(filename + SUMMARY_EXT);
// create summary file (if it doesn't exist) empty
DataUtilities.urlToFile(summaryURL).createNewFile();
this.cacheSize = cacheSize;
}
/**
* Index creation. Adds attribute name to summary and invokes attribute
* index creation.
*
* @param attribute
*/
public void createIndex(String attribute) throws FileNotFoundException, IOException {
URL url = getIndexURL(attribute);
if (url==null) {
addIndex(attribute);
url = getIndexURL(attribute);
}
synchronized (this) {
// now invokes AttributeIndexWriter to create the index
File f = DataUtilities.urlToFile(url);
if (f.exists()) {
if (!f.delete())
throw new IOException("File index cannot be deleted. Probably it's locked.");
}
RandomAccessFile raf = new RandomAccessFile(f, "rw");
FileChannel writeChannel = raf.getChannel();
AttributeIndexWriter indexWriter = new AttributeIndexWriter(attribute, writeChannel, getDBFChannel(),cacheSize);
indexWriter.buildIndex();
}
}
/**
* Returns the index for specified attribute
*
* @param attribute
* attribute to search for
* @return Index reader or null if such attribute doesn't have an index
*/
public AttributeIndexReader getIndex(String attribute) throws FileNotFoundException, IOException {
URL url = getIndexURL(attribute);
if (url == null)
return null;
File f = DataUtilities.urlToFile(url);
if (!f.exists())
return null;
RandomAccessFile raf = new RandomAccessFile(DataUtilities.urlToFile(url), "r");
return new AttributeIndexReader(attribute, raf.getChannel());
}
public boolean hasIndex(String attribute) throws FileNotFoundException, IOException {
URL url = getIndexURL(attribute);
if (url == null)
return false;
return DataUtilities.urlToFile(url).exists();
}
/**
* Tests whether an index for this attribute exists.
*
* @param attribute
* @return
*/
public boolean existsIndex(String attribute) throws FileNotFoundException, IOException {
URL url = getIndexURL(attribute);
if (url == null)
return false;
File f = DataUtilities.urlToFile(url);
return f.exists();
}
/**
* Returns the index URL for specified attribute
*
* @param attribute
* attribute to search for
* @return URL to index file or null if such attribute doesn't have an index
*/
protected URL getIndexURL(String attribute) throws FileNotFoundException, IOException {
File f = DataUtilities.urlToFile(summaryURL);
BufferedReader in = new BufferedReader(new FileReader(f));
int count = 0;
while (in.ready()) {
String s = in.readLine();
count++;
if (s.equals(attribute)) {
// index name: filename + number of row in index summary +
// extension
return new URL(filename+INDEX_EXT+SUFFIX.format(count));
}
}
return null; // index not found
}
protected synchronized void addIndex(String attribute) throws FileNotFoundException, IOException {
File f = DataUtilities.urlToFile(summaryURL);
PrintWriter out = new PrintWriter(new FileWriter(f,true));
out.println(attribute);
out.flush();
out.close();
}
protected FileChannel getDBFChannel() throws FileNotFoundException, MalformedURLException {
URL url = new URL(filename+".dbf");
File f = DataUtilities.urlToFile(url);
if (!f.exists())
url = new URL(filename+".DBF");
f = DataUtilities.urlToFile(url);
if (!f.exists())
throw new FileNotFoundException("DBF file not found");
RandomAccessFile raf = new RandomAccessFile(f, "r");
return raf.getChannel();
}
}