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Maven Package for datafile.sourceforge.net Java data file read/write utility that provides a convenient set of interfaces for reading and writing data to and from files in widely accepted format such as comma separated values (CSV), fixed width, tab separated, as well as others.
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/*
 * $Id: DataFileWriter.java,v 1.3 2005/12/20 11:33:40 oldman1004 Exp $
 * 
 * Copyright(c) 2002 Infomata
 * 
 * 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
 */
package com.infomata.data;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.URL;
import java.text.NumberFormat;

// TODO: create separate test for DataFileWriter and test encoding
// TODO: test URL write (jar file?)

/**
 * 
 * Writer implementation of DataFile. As the name suggests, an instance of
 * DataFileWriter is used for writing data files in specified formats.
 * 
 * USAGE:
 * 
 *  * // Creating a writer for data file with European encoding
 * // ISO-8859-2 (European) using tab separated format.
 * // (rewrite existing file)
 * 
 * DataFile write = DataFile.createWriter("8859_2", false);
 * write.setDataFormat(new TabFormat());
 * 
 * try
 * {
 * 
 *     write.open(new File("/data/test.txt"));
 * 
 *     for (DataRow row = write.next(); row != null; row = write.next())
 *     {
 *         row.add("some German text");
 *         row.add(123);
 *         row.add(13323.23d);
 *     }
 * }
 * 
 * finally
 * {
 *     write.close();
 * }
 * 
 * 
 * @author Sam Kim
 * @version $Revision: 1.3 $
 */
public class DataFileWriter extends AbstractDataFile
{
    private DataRow row = null;

    private PrintWriter out = null;

    /**
     * Flag that indicates whether or not the new data is to appended to
     * file if it exists.
     */
    private boolean append = false;

    /**
     * Creates a new DataFile instance for writing data files.
     * 
     * @param enc character encoding supported by Java.
     */
    public DataFileWriter(String enc)
    {
        nf = NumberFormat.getInstance();
        setCharacterEncoding(enc);
    }

    /**
     * Interface for specifying if data should be added to the output file if it
     * exists.
     * 
     * @param append true if the data is to be appended to the file. false
     *               to overwrite existing content.
     */
    public void setAppendToFile(boolean append)
    {
        this.append = append;
    }

    /**
     * Finalization method that closes the file descriptor. This would work only
     * if JVM is current (1.3 or later?).
     */
    public void finalize()
    {
        try
        {
            close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    } // finalize()

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#close()
     */
    public final void close() throws IOException
    {
        if (containsHeader())
        {
            resetHeaders();
        }

        if (out != null)
        {
            if (row != null && row.size() > 0)
            {
                out.println(format.format(row));
                row = null;
            }
            out.close();
        }

    } // close()

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#open(java.io.File)
     */
    public final void open(File file) throws IOException
    {
        if (!file.exists() && !file.createNewFile())
        {
            throw new IOException("Can't create file: "
                    + file.getAbsolutePath());
        }

        if (out != null)
        {
            close();
        }

        open(file.toURL());
    }

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#open(java.net.URL)
     */
    public final void open(URL file) throws IOException
    {
        if (containsCharacterEncoding())
        {
            FileOutputStream fos = new FileOutputStream(file.getFile(), append);
            OutputStreamWriter ow = new OutputStreamWriter(fos,
                    getCharacterEncoding());
            out = new PrintWriter(ow);
        }
        else
        {
            FileWriter fw = new FileWriter(file.getFile(), append);
            out = new PrintWriter(new BufferedWriter(fw));
        }

        if (format == null)
        {
            format = new CSVFormat();
        }

    } // open()

    /*
     * (non-Javadoc)
     * @see com.infomata.data.DataFile#next()
     */
    public final DataRow next() throws IOException
    {
        if (row == null)
        {
            row = new DataRow(nf);
        }
        else
        {
            if (row.size() == 0)
            {
                out.println("");
            }
            else
            {
                out.println(format.format(row));
            }
            row.clear();
        }
        return row;

    } // next()

}