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The main module contains the GeoTools public interfaces that are used by other GeoTools modules (and GeoTools applications). Where possible we make use industry standard terms as provided by OGC and ISO standards. The formal GeoTools public api consists of gt-metadata, jts and the gt-main module. The main module contains the default implementations that are available provided to other GeoTools modules using our factory system. Factories are obtained from an appropriate FactoryFinder, giving applications a chance configure the factory used using the Factory Hints facilities. FilterFactory ff = CommonFactoryFinder.getFilterFactory(); Expression expr = ff.add( expression1, expression2 ); If you find yourself using implementation specific classes chances are you doing it wrong: Expression expr = new AddImpl( expression1, expressiom2 );

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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2003-2008, 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;

import java.io.Closeable;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import org.geotools.referencing.ReferencingFactoryFinder;
import org.geotools.util.NIOUtilities;
import org.geotools.util.factory.Hints;
import org.opengis.referencing.FactoryException;
import org.opengis.referencing.crs.CoordinateReferenceSystem;

/**
 * @author Simone Giannecchini
 * @since 2.3
 */
public class PrjFileReader implements Closeable {

    /* Used to check if we can use memory mapped buffers safely. In case the OS cannot be detected, we act as if it was Windows and
     * do not use memory mapped buffers */
    private static final Boolean USE_MEMORY_MAPPED_BUFFERS =
            !System.getProperty("os.name", "Windows").contains("Windows");

    ByteBuffer buffer;

    ReadableByteChannel channel;

    CharBuffer charBuffer;

    CharsetDecoder decoder;

    CoordinateReferenceSystem crs;

    /**
     * Load the index file from the given channel.
     *
     * @param channel The channel to read from.
     * @throws IOException If an error occurs.
     */
    public PrjFileReader(ReadableByteChannel channel) throws IOException, FactoryException {
        this(channel, null);
    }

    /**
     * Load the index file from the given channel.
     *
     * @param channel The channel to read from.
     * @throws IOException If an error occurs.
     */
    public PrjFileReader(ReadableByteChannel channel, final Hints hints)
            throws IOException, FactoryException {
        try {
            Charset chars = Charset.forName("ISO-8859-1");
            decoder = chars.newDecoder();
            this.channel = channel;

            init();

            // ok, everything is ready...
            decoder.decode(buffer, charBuffer, true);
            buffer.limit(buffer.capacity());
            charBuffer.flip();
            crs =
                    ReferencingFactoryFinder.getCRSFactory(hints)
                            .createFromWKT(charBuffer.toString());
        } finally {
            // we are done reading, so just close this
            close();
        }
    }

    /**
     * Return the Coordinate Reference System retrieved by this reader.
     *
     * @return the Coordinate Reference System
     */
    public CoordinateReferenceSystem getCoordinateReferenceSystem() {
        return crs;
    }

    private int fill(ByteBuffer buffer, ReadableByteChannel channel) throws IOException {
        int r = buffer.remaining();
        // channel reads return -1 when EOF or other error
        // because they a non-blocking reads, 0 is a valid return value!!
        while (buffer.remaining() > 0 && r != -1) {
            r = channel.read(buffer);
        }
        if (r == -1) {
            buffer.limit(buffer.position());
        }
        return r;
    }

    @SuppressWarnings("PMD.CloseResource") // channel kept as field
    private void init() throws IOException {
        // create the ByteBuffer
        // if we have a FileChannel, lets map it
        if (channel instanceof FileChannel && USE_MEMORY_MAPPED_BUFFERS) {
            FileChannel fc = (FileChannel) channel;
            buffer = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
            ((Buffer) buffer).position((int) fc.position());
        } else {
            // Some other type of channel
            // start with a 8K buffer, should be more than adequate
            int size = 8 * 1024;
            // if for some reason its not, resize it
            // size = header.getRecordLength() > size ? header.getRecordLength()
            // : size;
            buffer = ByteBuffer.allocateDirect(size);
            // fill it and reset
            fill(buffer, channel);
            buffer.flip();
        }

        // The entire file is in little endian
        buffer.order(ByteOrder.LITTLE_ENDIAN);

        charBuffer = CharBuffer.allocate(8 * 1024);
        Charset chars = Charset.forName("ISO-8859-1");
        decoder = chars.newDecoder();
    }

    /**
     * The reader will close itself right after reading the CRS from the prj file, so no actual need
     * to call it explicitly anymore.
     */
    public void close() throws IOException {
        if (buffer != null) {
            NIOUtilities.clean(buffer); // will close if a MappedByteBuffer
            buffer = null;
        }
        if (channel.isOpen()) {
            channel.close();
        }
    }
}