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A simple library for reading and writing CSV in Java
package com.opencsv;
/*
Copyright 2015 Bytecode Pty Ltd.
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.
*/
import java.io.*;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
/**
* A very simple CSV writer released under a commercial-friendly license.
*
* @author Glen Smith
*/
public class CSVWriter implements Closeable, Flushable {
public static final int INITIAL_STRING_SIZE = 1024;
/**
* The character used for escaping quotes.
*/
public static final char DEFAULT_ESCAPE_CHARACTER = '"';
/**
* The default separator to use if none is supplied to the constructor.
*/
public static final char DEFAULT_SEPARATOR = ',';
/**
* The default quote character to use if none is supplied to the
* constructor.
*/
public static final char DEFAULT_QUOTE_CHARACTER = '"';
/**
* The quote constant to use when you wish to suppress all quoting.
*/
public static final char NO_QUOTE_CHARACTER = '\u0000';
/**
* The escape constant to use when you wish to suppress all escaping.
*/
public static final char NO_ESCAPE_CHARACTER = '\u0000';
/**
* Default line terminator.
*/
public static final String DEFAULT_LINE_END = "\n";
/**
* RFC 4180 compliant line terminator.
*/
public static final String RFC4180_LINE_END = "\r\n";
protected final Writer writer;
protected final char separator;
protected final char quotechar;
protected final char escapechar;
protected String lineEnd;
protected ResultSetHelper resultService;
protected volatile IOException exception;
/**
* Constructs CSVWriter using a comma for the separator.
*
* @param writer The writer to an underlying CSV source.
*/
public CSVWriter(Writer writer) {
this(writer, DEFAULT_SEPARATOR);
}
/**
* Constructs CSVWriter with supplied separator.
*
* @param writer The writer to an underlying CSV source.
* @param separator The delimiter to use for separating entries.
* @deprecated Please use {@link CSVWriter#CSVWriter(java.io.Writer, char, char, char, java.lang.String)} instead.
*/
@Deprecated
public CSVWriter(Writer writer, char separator) {
this(writer, separator, DEFAULT_QUOTE_CHARACTER);
}
/**
* Constructs CSVWriter with supplied separator and quote char.
*
* @param writer The writer to an underlying CSV source.
* @param separator The delimiter to use for separating entries
* @param quotechar The character to use for quoted elements
* @deprecated Please use {@link CSVWriter#CSVWriter(java.io.Writer, char, char, char, java.lang.String)} instead.
*/
@Deprecated
public CSVWriter(Writer writer, char separator, char quotechar) {
this(writer, separator, quotechar, DEFAULT_ESCAPE_CHARACTER);
}
/**
* Constructs CSVWriter with supplied separator and quote char.
*
* @param writer The writer to an underlying CSV source.
* @param separator The delimiter to use for separating entries
* @param quotechar The character to use for quoted elements
* @param escapechar The character to use for escaping quotechars or escapechars
* @deprecated Please use {@link CSVWriter#CSVWriter(java.io.Writer, char, char, char, java.lang.String)} instead.
*/
@Deprecated
public CSVWriter(Writer writer, char separator, char quotechar, char escapechar) {
this(writer, separator, quotechar, escapechar, DEFAULT_LINE_END);
}
/**
* Constructs CSVWriter with supplied separator and quote char.
*
* @param writer The writer to an underlying CSV source.
* @param separator The delimiter to use for separating entries
* @param quotechar The character to use for quoted elements
* @param lineEnd The line feed terminator to use
* @deprecated Please use {@link CSVWriter#CSVWriter(java.io.Writer, char, char, char, java.lang.String)} instead.
*/
@Deprecated
public CSVWriter(Writer writer, char separator, char quotechar, String lineEnd) {
this(writer, separator, quotechar, DEFAULT_ESCAPE_CHARACTER, lineEnd);
}
/**
* Constructs CSVWriter with supplied separator, quote char, escape char and line ending.
*
* @param writer The writer to an underlying CSV source.
* @param separator The delimiter to use for separating entries
* @param quotechar The character to use for quoted elements
* @param escapechar The character to use for escaping quotechars or escapechars
* @param lineEnd The line feed terminator to use
*/
public CSVWriter(Writer writer, char separator, char quotechar, char escapechar, String lineEnd) {
this.writer = writer;
this.separator = separator;
this.quotechar = quotechar;
this.escapechar = escapechar;
this.lineEnd = lineEnd;
}
/**
* Writes iterable to a CSV file. The list is assumed to be a String[]
*
* @param allLines an Iterable of String[], with each String[] representing a line of
* the file.
* @param applyQuotesToAll true if all values are to be quoted. false if quotes only
* to be applied to values which contain the separator, escape,
* quote or new line characters.
*/
public void writeAll(Iterable allLines, boolean applyQuotesToAll) {
StringBuilder sb = new StringBuilder(INITIAL_STRING_SIZE);
try {
for (String[] line : allLines) {
writeNext(line, applyQuotesToAll, sb);
sb.setLength(0);
}
} catch (IOException e){
exception = e;
}
}
/**
* Writes the entire list to a CSV file.
* The list is assumed to be a String[].
*
* @param allLines A List of String[] with each String[] representing a line of
* the file.
* @param applyQuotesToAll True if all values are to be quoted. False if quotes only
* to be applied to values which contain the separator, escape,
* quote, or new line characters.
*/
public void writeAll(List allLines, boolean applyQuotesToAll) {
writeAll((Iterable)allLines, applyQuotesToAll);
}
/**
* Writes iterable to a CSV file. The list is assumed to be a String[]
*
* @param allLines an Iterable of String[], with each String[] representing a line of
* the file.
*/
public void writeAll(Iterable allLines) {
StringBuilder sb = new StringBuilder(INITIAL_STRING_SIZE);
try {
for (String[] line : allLines) {
writeNext(line, true, sb);
sb.setLength(0);
}
} catch (IOException e){
exception = e;
}
}
/**
* Writes the entire list to a CSV file.
* The list is assumed to be a String[].
*
* @param allLines A List of String[] with each String[] representing a line of
* the file.
*/
public void writeAll(List allLines) {
writeAll((Iterable)allLines);
}
/**
* Writes the column names.
*
* @param rs ResultSet containing column names.
* @param applyQuotesToAll Whether all header names should be quoted.
* @throws SQLException Thrown by {@link com.opencsv.ResultSetHelper#getColumnNames(java.sql.ResultSet)}
*/
protected void writeColumnNames(ResultSet rs, boolean applyQuotesToAll) throws SQLException {
writeNext(resultService().getColumnNames(rs), applyQuotesToAll);
}
/**
* Writes the entire ResultSet to a CSV file.
*
* The caller is responsible for closing the ResultSet. Values are not trimmed.
* Quotes are applied to all values in the output.
*
* @param rs The result set to write
* @param includeColumnNames True if you want column names in the output, false otherwise
* @throws java.io.IOException Thrown by ResultSetHelper.getColumnValues()
* @throws java.sql.SQLException Thrown by ResultSetHelper.getColumnValues()
*
* @return Number of lines written.
*/
public int writeAll(ResultSet rs, boolean includeColumnNames) throws SQLException, IOException {
return writeAll(rs, includeColumnNames, false, true);
}
/**
* Writes the entire ResultSet to a CSV file.
*
* The caller is responsible for closing the ResultSet. Quotes are applied to
* all values in the output.
*
* @param rs The Result set to write.
* @param includeColumnNames Include the column names in the output.
* @param trim Remove spaces from the data before writing.
*
* @throws java.io.IOException Thrown by ResultSetHelper.getColumnValues()
* @throws java.sql.SQLException Thrown by ResultSetHelper.getColumnValues()
*
* @return Number of lines written - including header.
*/
public int writeAll(ResultSet rs, boolean includeColumnNames, boolean trim) throws SQLException, IOException {
return writeAll(rs, includeColumnNames, trim, true);
}
/**
* Writes the entire ResultSet to a CSV file.
*
* The caller is responsible for closing the ResultSet.
*
* @param rs The Result set to write.
* @param includeColumnNames Include the column names in the output.
* @param trim Remove spaces from the data before writing.
* @param applyQuotesToAll Whether all values should be quoted.
*
* @throws java.io.IOException Thrown by ResultSetHelper.getColumnValues()
* @throws java.sql.SQLException Thrown by ResultSetHelper.getColumnValues()
*
* @return Number of lines written - including header.
*/
public int writeAll(ResultSet rs, boolean includeColumnNames, boolean trim, boolean applyQuotesToAll) throws SQLException, IOException {
int linesWritten = 0;
if (includeColumnNames) {
writeColumnNames(rs, applyQuotesToAll);
linesWritten++;
}
while (rs.next()) {
writeNext(resultService().getColumnValues(rs, trim), applyQuotesToAll);
linesWritten++;
}
return linesWritten;
}
/**
* Writes the next line to the file.
*
* @param nextLine A string array with each comma-separated element as a separate
* entry.
* @param applyQuotesToAll True if all values are to be quoted. False applies quotes only
* to values which contain the separator, escape, quote, or new line characters.
*/
public void writeNext(String[] nextLine, boolean applyQuotesToAll) {
try {
writeNext(nextLine, applyQuotesToAll, new StringBuilder(INITIAL_STRING_SIZE));
} catch (IOException e) {
exception = e;
}
}
/**
* Writes the next line to the file. This method is a fail-fast method that will throw the
* IOException of the writer supplied to the CSVWriter (if the Writer does not handle the exceptions itself like
* the PrintWriter class).
*
* @param nextLine a string array with each comma-separated element as a separate
* entry.
* @param applyQuotesToAll true if all values are to be quoted. false applies quotes only
* to values which contain the separator, escape, quote or new line characters.
* @param appendable Appendable used as buffer.
* @throws IOException Exceptions thrown by the writer supplied to CSVWriter.
*/
protected void writeNext(String[] nextLine, boolean applyQuotesToAll, Appendable appendable) throws IOException {
if (nextLine == null) {
return;
}
for (int i = 0; i < nextLine.length; i++) {
if (i != 0) {
appendable.append(separator);
}
String nextElement = nextLine[i];
if (nextElement == null) {
continue;
}
Boolean stringContainsSpecialCharacters = stringContainsSpecialCharacters(nextElement);
if ((applyQuotesToAll || stringContainsSpecialCharacters) && quotechar != NO_QUOTE_CHARACTER) {
appendable.append(quotechar);
}
if (stringContainsSpecialCharacters) {
processLine(nextElement, appendable);
} else {
appendable.append(nextElement);
}
if ((applyQuotesToAll || stringContainsSpecialCharacters) && quotechar != NO_QUOTE_CHARACTER) {
appendable.append(quotechar);
}
}
appendable.append(lineEnd);
writer.write(appendable.toString());
}
/**
* Writes the next line to the file.
*
* @param nextLine A string array with each comma-separated element as a separate
* entry.
*/
public void writeNext(String[] nextLine) {
writeNext(nextLine, true);
}
/**
* Checks to see if the line contains special characters.
* @param line Element of data to check for special characters.
* @return True if the line contains the quote, escape, separator, newline, or return.
*/
protected boolean stringContainsSpecialCharacters(String line) {
return line.indexOf(quotechar) != -1
|| line.indexOf(escapechar) != -1
|| line.indexOf(separator) != -1
|| line.contains(DEFAULT_LINE_END)
|| line.contains("\r");
}
/**
* Processes all the characters in a line.
* @param nextElement Element to process.
* @param appendable - Appendable holding the processed data.
* @throws IOException - IOException thrown by the writer supplied to the CSVWriter
*/
protected void processLine(String nextElement, Appendable appendable) throws IOException {
for (int j = 0; j < nextElement.length(); j++) {
char nextChar = nextElement.charAt(j);
processCharacter(appendable, nextChar);
}
}
/**
* Appends the character to the StringBuilder adding the escape character if needed.
* @param appendable - Appendable holding the processed data.
* @param nextChar Character to process
* @throws IOException - IOException thrown by the writer supplied to the CSVWriter.
*/
protected void processCharacter(Appendable appendable, char nextChar) throws IOException {
if (escapechar != NO_ESCAPE_CHARACTER && checkCharactersToEscape(nextChar)) {
appendable.append(escapechar);
}
appendable.append(nextChar);
}
/**
* Checks whether the next character that is to be written out is a special
* character that must be quoted.
* The quote character, escape charater, and separator are special characters.
*
* @param nextChar The next character to be written
* @return Whether the character needs to be quoted or not
*/
protected boolean checkCharactersToEscape(char nextChar) {
return quotechar == NO_QUOTE_CHARACTER
? (nextChar == quotechar || nextChar == escapechar || nextChar == separator || nextChar == '\n')
: (nextChar == quotechar || nextChar == escapechar);
}
/**
* Flush underlying stream to writer.
*
* @throws IOException If bad things happen
*/
@Override
public void flush() throws IOException {
writer.flush();
}
/**
* Close the underlying stream writer flushing any buffered content.
*
* @throws IOException If bad things happen
*/
@Override
public void close() throws IOException {
flush();
writer.close();
}
/**
* Flushes the buffer and checks to see if the there has been an error in the printstream.
*
* @return True if the print stream has encountered an error
* either on the underlying output stream or during a format
* conversion.
*/
public boolean checkError() {
if (writer instanceof PrintWriter) {
PrintWriter pw = (PrintWriter) writer;
return pw.checkError();
}
flushQuietly(); // checkError in the PrintWriter class flushes the buffer so we shall too.
return exception != null;
}
/**
* Sets the result service.
* @param resultService The ResultSetHelper
*/
public void setResultService(ResultSetHelper resultService) {
this.resultService = resultService;
}
/**
* Lazy resultSetHelper creation.
* @return Instance of resultSetHelper
*/
protected ResultSetHelper resultService(){
if (resultService == null){
resultService = new ResultSetHelperService();
}
return resultService;
}
/**
* Flushes the writer without throwing any exceptions.
*/
public void flushQuietly() {
try {
flush();
} catch (IOException e) {
// catch exception and ignore.
}
}
}