root / trunk / libraries / libFMap / src / com / iver / cit / gvsig / fmap / drivers / shp / DbaseFileReaderNIO.java @ 1100
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/*
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* Geotools - OpenSource mapping toolkit
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* (C) 2002, Centre for Computational Geography
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; 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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* This file is based on an origional contained in the GISToolkit project:
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* http://gistoolkit.sourceforge.net/
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*
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*/
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/* gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana
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*
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* Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (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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* For more information, contact:
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*
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* Generalitat Valenciana
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* Conselleria d'Infraestructures i Transport
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* Av. Blasco Ib??ez, 50
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* 46010 VALENCIA
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* SPAIN
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*
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* +34 963862235
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* gvsig@gva.es
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* www.gvsig.gva.es
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*
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* or
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*
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* IVER T.I. S.A
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* Salamanca 50
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* 46005 Valencia
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* Spain
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*
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* +34 963163400
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* dac@iver.es
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*/
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package com.iver.cit.gvsig.fmap.drivers.shp; |
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import java.io.*; |
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import java.util.*; |
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import java.nio.*; |
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import java.nio.channels.ReadableByteChannel; |
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import java.nio.channels.FileChannel; |
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import java.nio.charset.Charset; |
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import java.nio.charset.CharsetDecoder; |
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import org.geotools.resources.NumberParser; |
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import org.geotools.resources.NIOUtilities; |
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/** A DbaseFileReader is used to read a dbase III format file.
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* <br>
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* The general use of this class is:
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* <CODE><PRE>
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* FileChannel in = new FileInputStream("thefile.dbf").getChannel();
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* DbaseFileReader r = new DbaseFileReader( in )
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* Object[] fields = new Object[r.getHeader().getNumFields()];
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* while (r.hasNext()) {
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* r.readEntry(fields);
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* // do stuff
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* }
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* r.close();
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* </PRE></CODE>
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* For consumers who wish to be a bit more selective with their reading of rows,
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* the Row object has been added. The semantics are the same as using the
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* readEntry method, but remember that the Row object is always the same. The
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* values are parsed as they are read, so it pays to copy them out (as each call
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* to Row.read() will result in an expensive String parse).
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* <br><b>EACH CALL TO readEntry OR readRow ADVANCES THE FILE!</b><br>
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* An example of using the Row method of reading:
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* <CODE><PRE>
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* FileChannel in = new FileInputStream("thefile.dbf").getChannel();
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* DbaseFileReader r = new DbaseFileReader( in )
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* int fields = r.getHeader().getNumFields();
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* while (r.hasNext()) {
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* DbaseFileReader.Row row = r.readRow();
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* for (int i = 0; i < fields; i++) {
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* // do stuff
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* Foo.bar( row.read(i) );
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* }
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* }
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* r.close();
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* </PRE></CODE>
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*
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* @author Ian Schneider
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*/
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public class DbaseFileReaderNIO { |
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public final class Row { |
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public Object read(int column) throws IOException { |
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int offset = getOffset(column);
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return readObject(offset, column);
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} |
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} |
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DbaseFileHeaderNIO header; |
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ByteBuffer buffer;
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ReadableByteChannel channel;
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CharBuffer charBuffer;
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CharsetDecoder decoder;
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char[] fieldTypes; |
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int[] fieldLengths; |
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int cnt = 1; |
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Row row; |
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NumberParser numberParser = new NumberParser();
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/** Creates a new instance of DBaseFileReader
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* @param channel The readable channel to use.
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* @throws IOException If an error occurs while initializing.
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*/
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public DbaseFileReaderNIO(ReadableByteChannel channel) throws IOException { |
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this.channel = channel;
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header = new DbaseFileHeaderNIO();
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///header.readHeader(channel);
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init(); |
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} |
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private int fill(ByteBuffer buffer,ReadableByteChannel channel) throws IOException { |
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int r = buffer.remaining();
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// channel reads return -1 when EOF or other error
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// because they a non-blocking reads, 0 is a valid return value!!
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while (buffer.remaining() > 0 && r != -1) { |
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r = channel.read(buffer); |
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} |
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if (r == -1) { |
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buffer.limit(buffer.position()); |
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} |
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return r;
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} |
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private void bufferCheck() throws IOException { |
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// remaining is less than record length
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// compact the remaining data and read again
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if (!buffer.isReadOnly() && buffer.remaining() < header.getRecordLength()) {
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buffer.compact(); |
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fill(buffer,channel); |
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buffer.position(0);
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} |
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} |
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private int getOffset(int column) { |
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int offset = 0; |
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for (int i = 0, ii = column; i < ii; i++) { |
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offset += fieldLengths[i]; |
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} |
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return offset;
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} |
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private void init() throws IOException { |
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// create the ByteBuffer
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// if we have a FileChannel, lets map it
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if (channel instanceof FileChannel) { |
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FileChannel fc = (FileChannel) channel; |
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buffer = fc.map(FileChannel.MapMode.READ_ONLY,0,fc.size()); |
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buffer.position((int) fc.position());
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} else {
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// Some other type of channel
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// start with a 8K buffer, should be more than adequate
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int size = 8 * 1024; |
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// if for some reason its not, resize it
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size = header.getRecordLength() > size ? header.getRecordLength() : size; |
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buffer = ByteBuffer.allocateDirect(size);
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// fill it and reset
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fill(buffer,channel); |
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buffer.flip(); |
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} |
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// The entire file is in little endian
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buffer.order(ByteOrder.LITTLE_ENDIAN);
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// Set up some buffers and lookups for efficiency
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fieldTypes = new char[header.getNumFields()]; |
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fieldLengths = new int[header.getNumFields()]; |
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for (int i = 0, ii = header.getNumFields(); i < ii; i++) { |
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fieldTypes[i] = header.getFieldType(i); |
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fieldLengths[i] = header.getFieldLength(i); |
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} |
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charBuffer = CharBuffer.allocate(header.getRecordLength() - 1); |
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Charset chars = Charset.forName("ISO-8859-1"); |
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decoder = chars.newDecoder(); |
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row = new Row();
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} |
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/** Get the header from this file. The header is read upon instantiation.
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* @return The header associated with this file or null if an error occurred.
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*/
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public DbaseFileHeaderNIO getHeader() {
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return header;
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} |
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/** Clean up all resources associated with this reader.<B>Highly recomended.</B>
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* @throws IOException If an error occurs.
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*/
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public void close() throws IOException { |
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if (channel.isOpen()) {
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channel.close(); |
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} |
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if (buffer instanceof MappedByteBuffer) { |
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NIOUtilities.clean(buffer); |
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} |
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buffer = null;
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channel = null;
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charBuffer = null;
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decoder = null;
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header = null;
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row = null;
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} |
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/** Query the reader as to whether there is another record.
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* @return True if more records exist, false otherwise.
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*/
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public boolean hasNext() { |
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return cnt < header.getNumRecords() + 1; |
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} |
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/** Get the next record (entry). Will return a new array of values.
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* @throws IOException If an error occurs.
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* @return A new array of values.
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*/
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public Object[] readEntry() throws IOException { |
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return readEntry(new Object[header.getNumFields()]); |
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} |
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public Row readRow() throws IOException { |
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read(); |
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return row;
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} |
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/** Skip the next record.
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* @throws IOException If an error occurs.
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*/
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public void skip() throws IOException { |
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boolean foundRecord = false; |
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while (!foundRecord) {
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bufferCheck(); |
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// read the deleted flag
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char tempDeleted = (char) buffer.get(); |
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// skip the next bytes
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buffer.position(buffer.position() + header.getRecordLength() - 1); //the 1 is for the deleted flag just read. |
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// add the row if it is not deleted.
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if (tempDeleted != '*') { |
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foundRecord = true;
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} |
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} |
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} |
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/** Copy the next record into the array starting at offset.
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* @param entry Th array to copy into.
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* @param offset The offset to start at
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* @throws IOException If an error occurs.
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* @return The same array passed in.
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*/
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public Object[] readEntry(Object[] entry,final int offset) throws IOException { |
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if (entry.length - offset < header.getNumFields()) {
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throw new ArrayIndexOutOfBoundsException(); |
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} |
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read(); |
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// retrieve the record length
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final int numFields = header.getNumFields(); |
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int fieldOffset = 0; |
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for (int j=0; j < numFields; j++){ |
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entry[j + offset] = readObject(fieldOffset,j); |
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fieldOffset += fieldLengths[j]; |
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} |
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return entry;
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} |
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/**
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* Transfer, by bytes, the next record to the writer.
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*/
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public void transferTo(DbaseFileWriterNIO writer) throws IOException { |
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bufferCheck(); |
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buffer.limit(buffer.position() + header.getRecordLength()); |
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writer.channel.write(buffer); |
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buffer.limit(buffer.capacity()); |
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cnt++; |
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} |
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private void read() throws IOException { |
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boolean foundRecord = false; |
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while (!foundRecord) {
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bufferCheck(); |
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// read the deleted flag
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char deleted = (char) buffer.get(); |
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if (deleted == '*') { |
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continue;
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} |
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charBuffer.position(0);
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buffer.limit(buffer.position() + header.getRecordLength() - 1);
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decoder.decode(buffer,charBuffer,true);
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buffer.limit(buffer.capacity()); |
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charBuffer.flip(); |
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foundRecord = true;
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} |
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cnt++; |
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} |
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/** Copy the next entry into the array.
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* @param entry The array to copy into.
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* @throws IOException If an error occurs.
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* @return The same array passed in.
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*/
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public Object[] readEntry(Object[] entry) throws IOException { |
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return readEntry(entry,0); |
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} |
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private Object readObject(final int fieldOffset,final int fieldNum) throws IOException { |
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final char type = fieldTypes[fieldNum]; |
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final int fieldLen = fieldLengths[fieldNum]; |
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Object object = null; |
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//System.out.println( charBuffer.subSequence(fieldOffset,fieldOffset + fieldLen));
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if(fieldLen > 0) { |
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switch (type){
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// (L)logical (T,t,F,f,Y,y,N,n)
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case 'l': |
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case 'L': |
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switch (charBuffer.charAt(fieldOffset)) {
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case 't': case 'T': case 'Y': case 'y': |
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object = Boolean.TRUE;
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break;
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case 'f': case 'F': case 'N': case 'n': |
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object = Boolean.FALSE;
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break;
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default:
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throw new IOException("Unknown logical value : '" + charBuffer.charAt(fieldOffset) + "'"); |
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} |
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break;
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// (C)character (String)
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case 'c': |
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case 'C': |
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// oh, this seems like a lot of work to parse strings...but,
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// For some reason if zero characters ( (int) char == 0 ) are allowed
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// in these strings, they do not compare correctly later on down the
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// line....
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int start = fieldOffset;
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int end = fieldOffset + fieldLen - 1; |
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// trim off whitespace and 'zero' chars
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while (start < end) {
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char c = charBuffer.get(start);
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if (c== 0 || Character.isWhitespace(c)) { |
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start++; |
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} |
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else break; |
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} |
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while (end > start) {
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char c = charBuffer.get(end);
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if (c == 0 || Character.isWhitespace(c)) { |
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end--; |
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} |
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else break; |
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} |
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// set up the new indexes for start and end
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charBuffer.position(start).limit(end + 1);
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String s = charBuffer.toString();
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// this resets the limit...
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charBuffer.clear(); |
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object = s; |
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break;
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// (D)date (Date)
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case 'd': |
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case 'D': |
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try{
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String tempString = charBuffer.subSequence(fieldOffset,fieldOffset + 4).toString(); |
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int tempYear = Integer.parseInt(tempString); |
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tempString = charBuffer.subSequence(fieldOffset + 4,fieldOffset + 6).toString(); |
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int tempMonth = Integer.parseInt(tempString) - 1; |
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tempString = charBuffer.subSequence(fieldOffset + 6,fieldOffset + 8).toString(); |
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int tempDay = Integer.parseInt(tempString); |
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Calendar cal = Calendar.getInstance(); |
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cal.clear(); |
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cal.set(cal.YEAR,tempYear); |
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cal.set(cal.MONTH, tempMonth); |
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cal.set(cal.DAY_OF_MONTH, tempDay); |
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object = cal.getTime(); |
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} |
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catch(NumberFormatException nfe){ |
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//todo: use progresslistener, this isn't a grave error.
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} |
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break;
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// (F)floating (Double)
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case 'n': |
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case 'N': |
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try {
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if (header.getFieldDecimalCount(fieldNum) == 0) { |
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object = new Integer(numberParser.parseInt(charBuffer, fieldOffset, fieldOffset + fieldLen - 1)); |
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break;
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} |
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// else will fall through to the floating point number
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} catch (NumberFormatException e) { |
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// todo: use progresslistener, this isn't a grave error.
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// don't do this!!! the Double parse will be attemted as we fall
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// through, so no need to create a new Object. -IanS
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//object = new Integer(0);
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// Lets try parsing a long instead...
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try {
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object = new Long(numberParser.parseLong(charBuffer,fieldOffset,fieldOffset + fieldLen - 1)); |
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break;
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} catch (NumberFormatException e2) { |
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} |
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} |
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case 'f': |
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case 'F': // floating point number |
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try {
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object = new Double(numberParser.parseDouble(charBuffer,fieldOffset, fieldOffset + fieldLen - 1)); |
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} catch (NumberFormatException e) { |
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// todo: use progresslistener, this isn't a grave error, though it
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// does indicate something is wrong
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// okay, now whatever we got was truly undigestable. Lets go with
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// a zero Double.
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object = new Double(0.0); |
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} |
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break;
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default:
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throw new IOException("Invalid field type : " + type); |
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} |
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} |
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return object;
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} |
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public static void main(String[] args) throws Exception { |
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/* FileChannel channel = new FileInputStream(args[0]).getChannel();
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DbaseFileReaderNIO reader = new DbaseFileReaderNIO(channel);
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System.out.println(reader.getHeader());
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int r = 0;
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while (reader.hasNext()) {
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System.out.println(++r + "," + java.util.Arrays.asList(reader.readEntry()));
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}
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*/
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} |
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} |