CSVData.java
package org.djutils.data.csv;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import org.djutils.data.DataColumn;
import org.djutils.data.DataRecord;
import org.djutils.data.DataTable;
import org.djutils.data.ListDataTable;
import org.djutils.data.SimpleDataColumn;
import org.djutils.data.serialization.TextSerializationException;
import org.djutils.data.serialization.TextSerializer;
import org.djutils.exceptions.Throw;
import org.djutils.primitives.Primitive;
import com.opencsv.CSVParserBuilder;
import com.opencsv.CSVReader;
import com.opencsv.CSVReaderBuilder;
import com.opencsv.CSVWriter;
import com.opencsv.ICSVWriter;
import com.opencsv.exceptions.CsvValidationException;
/**
* CSVData takes care of reading and writing of table data in CSV format. The class can be used, e.g., as follows:
*
* <pre>
* DataTable dataTable = new ListDataTable("data", "dataTable", columns);
* Writer writer = new FileWriter("c:/data/data.csv");
* Writer metaWriter = new FileWriter("c:/data/data.meta.csv");
* CSVData.writeData(writer, metaWriter, dataTable);
* </pre>
*
* Copyright (c) 2020-2020 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
* for project information <a href="https://djutils.org" target="_blank"> https://djutils.org</a>. The DJUTILS project is
* distributed under a three-clause BSD-style license, which can be found at
* <a href="https://djutils.org/docs/license.html" target="_blank"> https://djutils.org/docs/license.html</a>. <br>
* @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
* @author <a href="https://www.tudelft.nl/pknoppers">Peter Knoppers</a>
* @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
*/
public final class CSVData
{
/**
* Utility class, no public constructor.
*/
private CSVData()
{
// utility class
}
/**
* Write the data from the data table in CSV format. The writer writes the data, whereas the metaWriter writes the metadata.
* The metadata consists of a CSV file with three columns: the id, the description, and the class. The first row after the
* header contains the id, description, and class of the data table itself. The second and further rows contain information
* about the columns of the data table.
* @param writer Writer; the writer that writes the data, e.g. to a file
* @param metaWriter Writer; the writer for the metadata
* @param dataTable the data table to write
* @param separator char; the delimiter to use for separating entries
* @param quotechar char; the character to use for quoted elements
* @param escapechar char; the character to use for escaping quotechars or escapechars
* @param lineEnd String; the line feed terminator to use
* @throws IOException on I/O error when writing the data
* @throws TextSerializationException on unknown data type for serialization
*/
public static void writeData(final Writer writer, final Writer metaWriter, final DataTable dataTable, final char separator,
final char quotechar, final char escapechar, final String lineEnd) throws IOException, TextSerializationException
{
// Write the metadata file
CSVWriter csvMetaWriter = null;
CSVWriter csvWriter = null;
try
{
csvMetaWriter = new CSVWriter(metaWriter, separator, quotechar, escapechar, lineEnd);
csvMetaWriter.writeNext(new String[] { "id", "description", "className" });
csvMetaWriter
.writeNext(new String[] { dataTable.getId(), dataTable.getDescription(), dataTable.getClass().getName() });
for (DataColumn<?> column : dataTable.getColumns())
{
csvMetaWriter
.writeNext(new String[] { column.getId(), column.getDescription(), column.getValueType().getName() });
}
// Assemble the serializer array
TextSerializer<?>[] serializers = new TextSerializer[dataTable.getNumberOfColumns()];
for (int i = 0; i < dataTable.getNumberOfColumns(); i++)
{
DataColumn<?> column = dataTable.getColumns().get(i);
serializers[i] = TextSerializer.resolve(column.getValueType());
}
// Write the data file
csvWriter = new CSVWriter(writer, separator, quotechar, escapechar, lineEnd);
csvWriter.writeNext(dataTable.getColumnIds());
String[] textFields = new String[dataTable.getNumberOfColumns()];
for (DataRecord record : dataTable)
{
Object[] values = record.getValues();
for (int i = 0; i < dataTable.getNumberOfColumns(); i++)
{
textFields[i] = serializers[i].serialize(values[i]);
}
csvWriter.writeNext(textFields);
}
}
finally
{
if (null != csvMetaWriter)
{
csvMetaWriter.close();
}
if (null != csvWriter)
{
csvWriter.close();
}
}
}
/**
* Write the data from the data table in CSV format. The writer writes the data, whereas the metaWriter writes the metadata.
* The metadata consists of a CSV file with three columns: the id, the description, and the class. The first row after the
* header contains the id, description, and class of the data table itself. The second and further rows contain information
* about the columns of the data table.
* @param writer Writer; the writer that writes the data, e.g. to a file
* @param metaWriter Writer; the writer for the metadata
* @param dataTable the data table to write
* @throws IOException on I/O error when writing the data
* @throws TextSerializationException on unknown data type for serialization
*/
public static void writeData(final Writer writer, final Writer metaWriter, final DataTable dataTable)
throws IOException, TextSerializationException
{
writeData(writer, metaWriter, dataTable, ICSVWriter.DEFAULT_SEPARATOR, ICSVWriter.DEFAULT_QUOTE_CHARACTER, '\\',
ICSVWriter.DEFAULT_LINE_END);
}
/**
* Write the data from the data table in CSV format.
* @param filename String; the file name to write the data to
* @param metaFilename String; the file name to write the metadata to
* @param dataTable the data table to write
* @throws IOException on I/O error when writing the data
* @throws TextSerializationException on unknown data type for serialization
*/
public static void writeData(final String filename, final String metaFilename, final DataTable dataTable)
throws IOException, TextSerializationException
{
FileWriter fw = null;
FileWriter mfw = null;
try
{
fw = new FileWriter(filename);
mfw = new FileWriter(metaFilename);
writeData(fw, mfw, dataTable);
}
finally
{
if (null != fw)
{
fw.close(); // May have already been closed when the CSV writer was closed, but multiple close is harmless
}
if (null != mfw)
{
mfw.close();
}
}
}
/**
* Read the data from the CSV-file into the data table. Use the metadata to reconstruct the data table.
* @param reader Reader; the reader that can read the data, e.g. from a file
* @param metaReader Reader; the writer for the metadata
* @return dataTable the data table reconstructed from the meta data and filled with the data
* @param separator char; the delimiter to use for separating entries
* @param quotechar char; the character to use for quoted elements
* @param escapechar char; the character to use for escaping quotechars or escapechars
* @param lineEnd String; the line feed terminator to use
* @throws IOException on I/O error when reading the data
* @throws CsvValidationException when the CSV data was not formatted right
* @throws TextSerializationException on unknown data type for serialization
*/
public static DataTable readData(final Reader reader, final Reader metaReader, final char separator, final char quotechar,
final char escapechar, final String lineEnd) throws IOException, CsvValidationException, TextSerializationException
{
CSVReader csvMetaReader = null;
CSVReader csvReader = null;
try
{
// Read the metadata file and reconstruct the data table
csvMetaReader = new CSVReaderBuilder(metaReader).withCSVParser(
new CSVParserBuilder().withSeparator(separator).withQuoteChar(quotechar).withEscapeChar(escapechar).build())
.build();
List<DataColumn<?>> columns = new ArrayList<>();
String[] header = csvMetaReader.readNext();
Throw.when(
header.length != 3 || !"id".equals(header[0]) || !"description".equals(header[1])
|| !"className".equals(header[2]),
IOException.class, "header of the metafile does not contain 'id, description, className' as fields");
// table metadata
String[] tableLine = csvMetaReader.readNext();
Throw.when(tableLine == null, IOException.class, "no table information in the metafile");
Throw.when(tableLine.length != 3, IOException.class, "table data in the metafile does not contain 3 fields");
Throw.when(!tableLine[2].endsWith("ListDataTable"), IOException.class,
"Currently, this method can only recreate a ListDataTable");
// column metadata
String[] line = csvMetaReader.readNext();
while (line != null)
{
Throw.when(line.length != 3, IOException.class, "column data in the metafile does not contain 3 fields");
String type = line[2];
Class<?> valueClass = Primitive.forName(type);
if (valueClass == null)
{
try
{
valueClass = Class.forName(type);
}
catch (ClassNotFoundException exception)
{
throw new IOException("Could not find class " + type, exception);
}
}
@SuppressWarnings({ "rawtypes", "unchecked" })
DataColumn<?> column = new SimpleDataColumn(line[0], line[1], valueClass);
columns.add(column);
line = csvMetaReader.readNext();
}
// create DataTable
ListDataTable dataTable = new ListDataTable(tableLine[0], tableLine[1], columns);
// Assemble the serializer array
TextSerializer<?>[] serializers = new TextSerializer[dataTable.getNumberOfColumns()];
for (int i = 0; i < dataTable.getNumberOfColumns(); i++)
{
DataColumn<?> column = dataTable.getColumns().get(i);
serializers[i] = TextSerializer.resolve(column.getValueType());
}
// Read the data file header
csvReader = new CSVReaderBuilder(reader).withCSVParser(
new CSVParserBuilder().withSeparator(separator).withQuoteChar(quotechar).withEscapeChar(escapechar).build())
.build();
header = csvReader.readNext();
Throw.when(header.length != columns.size(), IOException.class,
"Number of columns in the data file does not match column metadata size");
for (int i = 0; i < header.length; i++)
{
Throw.when(!header[i].equals(columns.get(i).getId()), IOException.class,
"Header for column %d in the data file does not match column metadata info", i);
}
// Read the data file records
String[] data = csvReader.readNext();
while (data != null)
{
Object[] values = new Object[columns.size()];
for (int i = 0; i < values.length; i++)
{
values[i] = serializers[i].deserialize(data[i]);
}
dataTable.addRecord(values);
data = csvReader.readNext();
}
return dataTable;
}
finally
{
if (null != csvMetaReader)
{
csvMetaReader.close();
}
if (null != csvReader)
{
csvReader.close();
}
}
}
/**
* Read the data from the CSV-file into the data table. Use the metadata to reconstruct the data table.
* @param reader Reader; the reader that can read the data, e.g. from a file
* @param metaReader Reader; the writer for the metadata
* @return dataTable the data table reconstructed from the meta data and filled with the data
* @throws IOException on I/O error when reading the data
* @throws CsvValidationException when the CSV data was not formatted right
* @throws TextSerializationException on unknown data type for serialization
*/
public static DataTable readData(final Reader reader, final Reader metaReader)
throws IOException, CsvValidationException, TextSerializationException
{
return readData(reader, metaReader, ICSVWriter.DEFAULT_SEPARATOR, ICSVWriter.DEFAULT_QUOTE_CHARACTER, '\\',
ICSVWriter.DEFAULT_LINE_END);
}
/**
* Read the data from the CSV-file into the data table. Use the metadata to reconstruct the data table.
* @param filename String; the file name to read the data from
* @param metaFilename String; the file name to read the metadata from
* @return dataTable the data table reconstructed from the meta data and filled with the data
* @throws IOException on I/O error when reading the data
* @throws CsvValidationException when the CSV data was not formatted right
* @throws TextSerializationException on unknown data type for serialization
*/
public static DataTable readData(final String filename, final String metaFilename)
throws IOException, CsvValidationException, TextSerializationException
{
FileReader fr = null;
FileReader mfr = null;
try
{
fr = new FileReader(filename);
mfr = new FileReader(metaFilename);
return readData(fr, mfr);
}
finally
{
if (null != fr)
{
fr.close(); // May have already been closed when the CSV reader was closed, but multiple close is harmless
}
if (null != mfr)
{
mfr.close();
}
}
}
}