com.vividsolutions.jts.io.WKTFileReader Maven / Gradle / Ivy
The newest version!
/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* 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; either
* version 2.1 of the License, or (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.io;
import java.io.*;
import java.util.*;
import com.vividsolutions.jts.geom.*;
/**
* Reads a sequence of {@link Geometry}s in WKT format
* from a text file.
* The geometries in the file may be separated by any amount
* of whitespace and newlines.
*
* @author Martin Davis
*
*/
public class WKTFileReader
{
private File file = null;
private Reader reader;
// private Reader fileReader = new FileReader(file);
private WKTReader wktReader;
private int count = 0;
private int limit = -1;
private int offset = 0;
/**
* Creates a new WKTFileReader given the File to read from
* and a WKTReader to use to parse the geometries.
*
* @param file the File to read from
* @param wktReader the geometry reader to use
*/
public WKTFileReader(File file, WKTReader wktReader)
{
this.file = file;
this.wktReader = wktReader;
}
/**
* Creates a new WKTFileReader, given the name of the file to read from.
*
* @param filename the name of the file to read from
* @param wktReader the geometry reader to use
*/
public WKTFileReader(String filename, WKTReader wktReader)
{
this(new File(filename), wktReader);
}
/**
* Creates a new WKTFileReader, given a {@link Reader} to read from.
*
* @param reader the reader to read from
* @param wktReader the geometry reader to use
*/
public WKTFileReader(Reader reader, WKTReader wktReader)
{
this.reader = reader;
this.wktReader = wktReader;
}
/**
* Sets the maximum number of geometries to read.
*
* @param limit the maximum number of geometries to read
*/
public void setLimit(int limit)
{
this.limit = limit;
}
/**
* Sets the number of geometries to skip before storing.
*
* @param offset the number of geometries to skip
*/
public void setOffset(int offset)
{
this.offset = offset;
}
/**
* Reads a sequence of geometries.
* If an offset is specified, geometries read up to the offset count are skipped.
* If a limit is specified, no more than limit geometries are read.
*
* @return the list of geometries read
* @throws IOException if an I/O exception was encountered
* @throws ParseException if an error occured reading a geometry
*/
public List read()
throws IOException, ParseException
{
// do this here so that constructors don't throw exceptions
if (file != null)
reader = new FileReader(file);
count = 0;
try {
BufferedReader bufferedReader = new BufferedReader(reader);
try {
return read(bufferedReader);
} finally {
bufferedReader.close();
}
} finally {
reader.close();
}
}
private List read(BufferedReader bufferedReader) throws IOException,
ParseException {
List geoms = new ArrayList();
while (! isAtEndOfFile(bufferedReader) && ! isAtLimit(geoms)) {
Geometry g = wktReader.read(bufferedReader);
if (count >= offset)
geoms.add(g);
count++;
}
return geoms;
}
private boolean isAtLimit(List geoms)
{
if (limit < 0) return false;
if (geoms.size() < limit) return false;
return true;
}
private static final int MAX_LOOKAHEAD = 1000;
/**
* Tests if reader is at EOF.
*/
private boolean isAtEndOfFile(BufferedReader bufferedReader)
throws IOException
{
bufferedReader.mark(MAX_LOOKAHEAD);
StreamTokenizer tokenizer = new StreamTokenizer(bufferedReader);
int type = tokenizer.nextToken();
if (type == StreamTokenizer.TT_EOF) {
return true;
}
bufferedReader.reset();
return false;
}
}