Java tutorial
/**
Copyright 2005 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.IOException;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;
import java.math.BigDecimal;
import java.sql.Clob;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Time;
import java.sql.Timestamp;
import java.sql.Types;
import java.text.SimpleDateFormat;
import java.util.Iterator;
import java.util.List;
/**
* A very simple CSV writer released under a commercial-friendly license.
*
* @author Glen Smith
*
*/
public class CSVWriter {
private Writer rawWriter;
private PrintWriter pw;
private char separator;
private char quotechar;
private char escapechar;
private String lineEnd;
/** 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 uses platform encoding. */
public static final String DEFAULT_LINE_END = "\n";
private static final SimpleDateFormat
TIMESTAMP_FORMATTER =
new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss");
private static final SimpleDateFormat
DATE_FORMATTER =
new SimpleDateFormat("dd-MMM-yyyy");
/**
* 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.
*/
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
*/
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
*/
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
*/
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.rawWriter = writer;
this.pw = new PrintWriter(writer);
this.separator = separator;
this.quotechar = quotechar;
this.escapechar = escapechar;
this.lineEnd = lineEnd;
}
/**
* 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) {
for (Iterator iter = allLines.iterator(); iter.hasNext();) {
String[] nextLine = (String[]) iter.next();
writeNext(nextLine);
}
}
protected void writeColumnNames(ResultSetMetaData metadata)
throws SQLException {
int columnCount = metadata.getColumnCount();
String[] nextLine = new String[columnCount];
for (int i = 0; i < columnCount; i++) {
nextLine[i] = metadata.getColumnName(i + 1);
}
writeNext(nextLine);
}
/**
* Writes the entire ResultSet to a CSV file.
*
* The caller is responsible for closing the ResultSet.
*
* @param rs the recordset to write
* @param includeColumnNames true if you want column names in the output, false otherwise
*
*/
public void writeAll(java.sql.ResultSet rs, boolean includeColumnNames) throws SQLException, IOException {
ResultSetMetaData metadata = rs.getMetaData();
if (includeColumnNames) {
writeColumnNames(metadata);
}
int columnCount = metadata.getColumnCount();
while (rs.next())
{
String[] nextLine = new String[columnCount];
for (int i = 0; i < columnCount; i++) {
nextLine[i] = getColumnValue(rs, metadata.getColumnType(i + 1), i + 1);
}
writeNext(nextLine);
}
}
private static String getColumnValue(ResultSet rs, int colType, int colIndex)
throws SQLException, IOException {
String value = "";
switch (colType)
{
case Types.BIT:
Object bit = rs.getObject(colIndex);
if (bit != null) {
value = String.valueOf(bit);
}
break;
case Types.BOOLEAN:
boolean b = rs.getBoolean(colIndex);
if (!rs.wasNull()) {
value = Boolean.valueOf(b).toString();
}
break;
case Types.CLOB:
Clob c = rs.getClob(colIndex);
if (c != null) {
value = read(c);
}
break;
case Types.BIGINT:
case Types.DECIMAL:
case Types.DOUBLE:
case Types.FLOAT:
case Types.REAL:
case Types.NUMERIC:
BigDecimal bd = rs.getBigDecimal(colIndex);
if (bd != null) {
value = "" + bd.doubleValue();
}
break;
case Types.INTEGER:
case Types.TINYINT:
case Types.SMALLINT:
int intValue = rs.getInt(colIndex);
if (!rs.wasNull()) {
value = "" + intValue;
}
break;
case Types.JAVA_OBJECT:
Object obj = rs.getObject(colIndex);
if (obj != null) {
value = String.valueOf(obj);
}
break;
case Types.DATE:
java.sql.Date date = rs.getDate(colIndex);
if (date != null) {
value = DATE_FORMATTER.format(date);;
}
break;
case Types.TIME:
Time t = rs.getTime(colIndex);
if (t != null) {
value = t.toString();
}
break;
case Types.TIMESTAMP:
Timestamp tstamp = rs.getTimestamp(colIndex);
if (tstamp != null) {
value = TIMESTAMP_FORMATTER.format(tstamp);
}
break;
case Types.LONGVARCHAR:
case Types.VARCHAR:
case Types.CHAR:
value = rs.getString(colIndex);
break;
default:
value = "";
}
if (value == null)
{
value = "";
}
return value;
}
private static String read(Clob c) throws SQLException, IOException
{
StringBuffer sb = new StringBuffer( (int) c.length());
Reader r = c.getCharacterStream();
char[] cbuf = new char[2048];
int n = 0;
while ((n = r.read(cbuf, 0, cbuf.length)) != -1) {
if (n > 0) {
sb.append(cbuf, 0, n);
}
}
return sb.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) {
if (nextLine == null)
return;
StringBuffer sb = new StringBuffer();
for (int i = 0; i < nextLine.length; i++) {
if (i != 0) {
sb.append(separator);
}
String nextElement = nextLine[i];
if (nextElement == null)
continue;
if (quotechar != NO_QUOTE_CHARACTER)
sb.append(quotechar);
for (int j = 0; j < nextElement.length(); j++) {
char nextChar = nextElement.charAt(j);
if (escapechar != NO_ESCAPE_CHARACTER && nextChar == quotechar) {
sb.append(escapechar).append(nextChar);
} else if (escapechar != NO_ESCAPE_CHARACTER && nextChar == escapechar) {
sb.append(escapechar).append(nextChar);
} else {
sb.append(nextChar);
}
}
if (quotechar != NO_QUOTE_CHARACTER)
sb.append(quotechar);
}
sb.append(lineEnd);
pw.write(sb.toString());
}
/**
* Flush underlying stream to writer.
*
* @throws IOException if bad things happen
*/
public void flush() throws IOException {
pw.flush();
}
/**
* Close the underlying stream writer flushing any buffered content.
*
* @throws IOException if bad things happen
*
*/
public void close() throws IOException {
pw.flush();
pw.close();
rawWriter.close();
}
}
////////////////////////////////////////
/**
Copyright 2005 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.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;
import junit.framework.TestCase;
public class CSVWriterTest extends TestCase {
/**
* Test routine for converting output to a string.
*
* @param args
* the elements of a line of the cvs file
* @return a String version
* @throws IOException
* if there are problems writing
*/
private String invokeWriter(String[] args) throws IOException {
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw, ',', '\'');
csvw.writeNext(args);
return sw.toString();
}
/**
* Tests parsing individual lines.
*
* @throws IOException
* if the reader fails.
*/
public void testParseLine() throws IOException {
// test normal case
String[] normal = { "a", "b", "c" };
String output = invokeWriter(normal);
assertEquals("'a','b','c'\n", output);
// test quoted commas
String[] quoted = { "a", "b,b,b", "c" };
output = invokeWriter(quoted);
assertEquals("'a','b,b,b','c'\n", output);
// test empty elements
String[] empty = {,};
output = invokeWriter(empty);
assertEquals("\n", output);
// test multiline quoted
String[] multiline = { "This is a \n multiline entry", "so is \n this" };
output = invokeWriter(multiline);
assertEquals("'This is a \n multiline entry','so is \n this'\n", output);
}
/**
* Test parsing from to a list.
*
* @throws IOException
* if the reader fails.
*/
public void testParseAll() throws IOException {
List allElements = new ArrayList();
String[] line1 = "Name#Phone#Email".split("#");
String[] line2 = "Glen#1234#glen@abcd.com".split("#");
String[] line3 = "John#5678#john@efgh.com".split("#");
allElements.add(line1);
allElements.add(line2);
allElements.add(line3);
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw);
csvw.writeAll(allElements);
String result = sw.toString();
String[] lines = result.split("\n");
assertEquals(3, lines.length);
}
/**
* Tests the option of having omitting quotes in the output stream.
*
* @throws IOException if bad things happen
*/
public void testNoQuoteChars() throws IOException {
String[] line = { "Foo", "Bar", "Baz" };
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw, CSVWriter.DEFAULT_SEPARATOR, CSVWriter.NO_QUOTE_CHARACTER);
csvw.writeNext(line);
String result = sw.toString();
assertEquals("Foo,Bar,Baz\n", result);
}
/**
* Test null values.
*
* @throws IOException if bad things happen
*/
public void testNullValues() throws IOException {
String[] line = { "Foo", null, "Bar", "baz" };
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw);
csvw.writeNext(line);
String result = sw.toString();
assertEquals("\"Foo\",,\"Bar\",\"baz\"\n", result);
}
public void testStreamFlushing() throws IOException {
String WRITE_FILE = "myfile.csv";
String[] nextLine = new String[] { "aaaa", "bbbb", "cccc", "dddd" };
FileWriter fileWriter = new FileWriter(WRITE_FILE);
CSVWriter writer = new CSVWriter(fileWriter);
writer.writeNext(nextLine);
// If this line is not executed, it is not written in the file.
writer.close();
}
public void testAlternateEscapeChar() {
String[] line = { "Foo", "bar's" };
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw, CSVWriter.DEFAULT_SEPARATOR, CSVWriter.DEFAULT_QUOTE_CHARACTER, '\'');
csvw.writeNext(line);
assertEquals("\"Foo\",\"bar''s\"\n", sw.toString());
}
public void testNoQuotingNoEscaping() {
String[] line = { "\"Foo\",\"Bar\"" };
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw, CSVWriter.DEFAULT_SEPARATOR, CSVWriter.NO_QUOTE_CHARACTER,
CSVWriter.NO_ESCAPE_CHARACTER);
csvw.writeNext(line);
assertEquals("\"Foo\",\"Bar\"\n", sw.toString());
}
public void testNestedQuotes() {
String[] data = new String[] { "\"\"", "test" };
String oracle = new String("\"\"\"\"\"\",\"test\"\n");
CSVWriter writer = null;
File tempFile = null;
FileWriter fwriter = null;
try {
tempFile = File.createTempFile("csvWriterTest", ".csv");
tempFile.deleteOnExit();
fwriter = new FileWriter(tempFile);
writer = new CSVWriter(fwriter);
} catch (IOException e) {
fail();
}
// write the test data:
writer.writeNext(data);
try {
writer.close();
} catch (IOException e) {
fail();
}
try {
// assert that the writer was also closed.
fwriter.flush();
fail();
} catch (IOException e) {
// we should go through here..
}
// read the data and compare.
FileReader in = null;
try {
in = new FileReader(tempFile);
} catch (FileNotFoundException e) {
fail();
}
StringBuffer fileContents = new StringBuffer();
try {
int ch;
while ((ch = in.read()) != -1) {
fileContents.append((char) ch);
}
in.close();
} catch (IOException e) {
fail();
}
assertTrue(oracle.equals(fileContents.toString()));
}
public void testAlternateLineFeeds() {
String[] line = { "Foo", "Bar", "baz" };
StringWriter sw = new StringWriter();
CSVWriter csvw = new CSVWriter(sw, CSVWriter.DEFAULT_SEPARATOR, CSVWriter.DEFAULT_QUOTE_CHARACTER, "\r");
csvw.writeNext(line);
String result = sw.toString();
assertTrue(result.endsWith("\r"));
}
/**
* The Test Runner for commandline use.
*
* @param args
* no args required
*/
public static void main(String args[]) {
junit.textui.TestRunner.run(CSVWriterTest.class);
}
}