com.helger.commons.csv.CSVReader Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of ph-commons Show documentation
Show all versions of ph-commons Show documentation
Java 1.8+ Library with tons of utility classes required in all projects
/*
* Copyright (C) 2014-2024 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.helger.commons.csv;
import java.io.Closeable;
import java.io.IOException;
import java.io.Reader;
import java.io.UncheckedIOException;
import java.util.Iterator;
import java.util.function.Consumer;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.WillCloseWhenClosed;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.collection.impl.CommonsArrayList;
import com.helger.commons.collection.impl.ICommonsIterable;
import com.helger.commons.collection.impl.ICommonsList;
import com.helger.commons.io.stream.NonBlockingBufferedReader;
import com.helger.commons.io.stream.StreamHelper;
/**
* A very simple CSV reader released under a commercial-friendly license.
*
* @author Glen Smith
* @author Philip Helger
*/
public class CSVReader implements Closeable, ICommonsIterable >
{
private final Reader m_aReader;
private final ICSVLineReader m_aLineReader;
private final CSVParser m_aParser;
private int m_nSkipLines = CCSV.DEFAULT_SKIP_LINES;
private final boolean m_bKeepCR;
private boolean m_bVerifyReader = CCSV.DEFAULT_VERIFY_READER;
private boolean m_bHasNext = true;
private boolean m_bLinesSkiped = false;
/**
* Constructs CSVReader using a comma for the separator.
*
* @param aReader
* the reader to an underlying CSV source.
*/
public CSVReader (@Nonnull @WillCloseWhenClosed final Reader aReader)
{
this (aReader, new CSVParser (), CCSV.DEFAULT_KEEP_CR);
}
/**
* Constructs {@link CSVReader} using a comma for the separator.
*
* @param aReader
* the reader to an underlying CSV source.
* @param bKeepCR
* true to keep carriage returns in data read,
* false otherwise
*/
public CSVReader (@Nonnull @WillCloseWhenClosed final Reader aReader, final boolean bKeepCR)
{
this (aReader, new CSVParser (), bKeepCR);
}
/**
* Constructs {@link CSVReader} with supplied {@link CSVParser}.
*
* @param aReader
* the reader to an underlying CSV source.
* @param aParser
* the parser to use to parse input
* @param bKeepCR
* true to keep carriage returns in data read,
* false otherwise
*/
public CSVReader (@Nonnull @WillCloseWhenClosed final Reader aReader, @Nonnull final CSVParser aParser, final boolean bKeepCR)
{
ValueEnforcer.notNull (aReader, "Reader");
ValueEnforcer.notNull (aParser, "Parser");
Reader aInternallyBufferedReader = StreamHelper.getBuffered (aReader);
if (bKeepCR)
m_aLineReader = new CSVLineReaderKeepCR (aInternallyBufferedReader);
else
{
if (!(aInternallyBufferedReader instanceof NonBlockingBufferedReader))
{
// It is buffered, but we need it to support readLine
aInternallyBufferedReader = new NonBlockingBufferedReader (aInternallyBufferedReader);
}
m_aLineReader = new CSVLineReaderNonBlockingBufferedReader ((NonBlockingBufferedReader) aInternallyBufferedReader);
}
m_aReader = aInternallyBufferedReader;
m_aParser = aParser;
m_bKeepCR = bKeepCR;
}
/**
* @return the CSVParser used by the reader.
*/
@Nonnull
public CSVParser getParser ()
{
return m_aParser;
}
/**
* @return The default separator for this parser.
*/
public char getSeparatorChar ()
{
return m_aParser.getSeparatorChar ();
}
/**
* Sets the delimiter to use for separating entries.
*
* @param cSeparator
* the delimiter to use for separating entries
* @return this
*/
@Nonnull
public CSVReader setSeparatorChar (final char cSeparator)
{
m_aParser.setSeparatorChar (cSeparator);
return this;
}
/**
* @return The default quotation character for this parser.
*/
public char getQuoteChar ()
{
return m_aParser.getQuoteChar ();
}
/**
* Sets the character to use for quoted elements.
*
* @param cQuoteChar
* the character to use for quoted element.
* @return this
*/
@Nonnull
public CSVReader setQuoteChar (final char cQuoteChar)
{
m_aParser.setQuoteChar (cQuoteChar);
return this;
}
/**
* @return The default escape character for this parser.
*/
public char getEscapeChar ()
{
return m_aParser.getEscapeChar ();
}
/**
* Sets the character to use for escaping a separator or quote.
*
* @param cEscapeChar
* the character to use for escaping a separator or quote.
* @return this
*/
@Nonnull
public CSVReader setEscapeChar (final char cEscapeChar)
{
m_aParser.setEscapeChar (cEscapeChar);
return this;
}
/**
* @return The default strictQuotes setting for this parser.
*/
public boolean isStrictQuotes ()
{
return m_aParser.isStrictQuotes ();
}
/**
* Sets the strict quotes setting - if true, characters outside the quotes are
* ignored.
*
* @param bStrictQuotes
* if true, characters outside the quotes are ignored
* @return this
*/
@Nonnull
public CSVReader setStrictQuotes (final boolean bStrictQuotes)
{
m_aParser.setStrictQuotes (bStrictQuotes);
return this;
}
/**
* @return The default ignoreLeadingWhiteSpace setting for this parser.
*/
public boolean isIgnoreLeadingWhiteSpace ()
{
return m_aParser.isIgnoreLeadingWhiteSpace ();
}
/**
* Sets the ignore leading whitespace setting - if true, white space in front
* of a quote in a field is ignored.
*
* @param bIgnoreLeadingWhiteSpace
* if true, white space in front of a quote in a field is
* ignored
* @return this
*/
@Nonnull
public CSVReader setIgnoreLeadingWhiteSpace (final boolean bIgnoreLeadingWhiteSpace)
{
m_aParser.setIgnoreLeadingWhiteSpace (bIgnoreLeadingWhiteSpace);
return this;
}
/**
* @return the default ignoreQuotation setting for this parser.
*/
public boolean isIgnoreQuotations ()
{
return m_aParser.isIgnoreQuotations ();
}
/**
* Sets the ignore quotations mode - if true, quotations are
* ignored.
*
* @param bIgnoreQuotations
* if true, quotations are ignored
* @return this
*/
@Nonnull
public CSVReader setIgnoreQuotations (final boolean bIgnoreQuotations)
{
m_aParser.setIgnoreQuotations (bIgnoreQuotations);
return this;
}
/**
* Returns the number of lines in the csv file to skip before processing. This
* is useful when there is miscellaneous data at the beginning of a file.
*
* @return the number of lines in the csv file to skip before processing.
*/
@Nonnegative
public int getSkipLines ()
{
return m_nSkipLines;
}
/**
* Sets the line number to skip for start reading.
*
* @param nSkipLines
* the line number to skip for start reading.
* @return this
*/
@Nonnull
public CSVReader setSkipLines (@Nonnegative final int nSkipLines)
{
ValueEnforcer.isGE0 (nSkipLines, "SkipLines");
m_nSkipLines = nSkipLines;
return this;
}
/**
* Returns if the reader will keep carriage returns found in data or remove
* them.
*
* @return true if reader will keep carriage returns, false otherwise.
*/
public boolean isKeepCarriageReturns ()
{
return m_bKeepCR;
}
/**
* Returns if the {@link CSVReader} will verify the reader before each read.
*
* By default the value is true which is the functionality for version 3.0. If
* set to false the reader is always assumed ready to read - this is the
* functionality for version 2.4 and before.
* The reason this method was needed was that certain types of Readers would
* return false for its ready() method until a read was done (namely readers
* created using Channels). This caused opencsv not to read from those
* readers.
* Source: https://sourceforge.net/p/opencsv/bugs/108/
*
* @return true if CSVReader will verify the reader before reads.
* false otherwise.
*/
public boolean isVerifyReader ()
{
return m_bVerifyReader;
}
/**
* Checks to see if the CSVReader should verify the reader state before reads
* or not. This should be set to false if you are using some form of
* asynchronous reader (like readers created by the java.nio.* classes). The
* default value is true.
*
* @param bVerifyReader
* true if CSVReader should verify reader before each
* read, false otherwise.
* @return this
*/
@Nonnull
public CSVReader setVerifyReader (final boolean bVerifyReader)
{
m_bVerifyReader = bVerifyReader;
return this;
}
/**
* Reads the entire file into a list with each element being a list of
* {@link String} of tokens.
*
* @return a list of list of String, with each inner list of {@link String}
* representing a line of the file.
* @throws IOException
* if bad things happen during the read
*/
@Nonnull
@ReturnsMutableCopy
public ICommonsList > readAll () throws IOException
{
final ICommonsList > ret = new CommonsArrayList <> ();
while (m_bHasNext)
{
final ICommonsList aNextLineAsTokens = readNext ();
if (aNextLineAsTokens != null)
ret.add (aNextLineAsTokens);
}
return ret;
}
/**
* Reads the entire file line by line and invoke a callback for each line.
*
* @param aLineConsumer
* The consumer that is invoked for every line. May not be
* null.
* @throws IOException
* if bad things happen during the read
*/
public void readAll (@Nonnull final Consumer > aLineConsumer) throws IOException
{
while (m_bHasNext)
{
final ICommonsList aNextLineAsTokens = readNext ();
if (aNextLineAsTokens != null)
aLineConsumer.accept (aNextLineAsTokens);
}
}
/**
* Reads the next line from the buffer and converts to a string array.
*
* @return a string array with each comma-separated element as a separate
* entry.
* @throws IOException
* if bad things happen during the read
*/
@Nullable
public ICommonsList readNext () throws IOException
{
ICommonsList ret = null;
do
{
final String sNextLine = _getNextLine ();
if (!m_bHasNext)
{
// should throw if still pending?
return ret;
}
final ICommonsList r = m_aParser.parseLineMulti (sNextLine);
if (ret == null)
ret = r;
else
ret.addAll (r);
} while (m_aParser.isPending ());
return ret;
}
/**
* Reads the next line from the file.
*
* @return the next line from the file without trailing newline
* @throws IOException
* if bad things happen during the read
*/
@Nullable
private String _getNextLine () throws IOException
{
if (_isClosed ())
{
m_bHasNext = false;
return null;
}
if (!m_bLinesSkiped)
{
// Perform skip of lines exactly once
for (int i = 0; i < m_nSkipLines; i++)
m_aLineReader.readLine ();
m_bLinesSkiped = true;
}
if (!m_bHasNext)
return null;
final String sNextLine = m_aLineReader.readLine ();
if (sNextLine == null)
m_bHasNext = false;
return sNextLine;
}
/**
* Checks to see if the file is closed.
*
* @return true if the reader can no longer be read from.
*/
private boolean _isClosed ()
{
if (!m_bVerifyReader)
return false;
try
{
return !m_aReader.ready ();
}
catch (final IOException e)
{
return true;
}
}
/**
* Closes the underlying reader.
*
* @throws IOException
* if the close fails
*/
public void close () throws IOException
{
m_aReader.close ();
}
/**
* Creates an Iterator for processing the csv data.
*
* @return an ICommonsList<String> iterator.
*/
@Nonnull
public Iterator > iterator ()
{
try
{
return new CSVIterator (this);
}
catch (final IOException e)
{
throw new UncheckedIOException ("Error creating CSVIterator", e);
}
}
}