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| Reads CSV (Comma Separated Value) files | |
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/*------------------------------------------------------------------------------
Name: CSVReader.java
Project: jutils.org
Comment: Reads CSV (Comma Separated Value) files
Version: $Id: CSVReader.java,v 1.1 2004/04/07 07:40:45 laurent Exp $
Author: Roedy Green [email protected], Heinrich Goetzger [email protected]
------------------------------------------------------------------------------*/
import java.util.Vector;
import java.io.BufferedReader;
import java.io.EOFException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
/**
* Reads CSV (Comma Separated Value) files.
*
* This format is mostly used my Microsoft Word and Excel.
* Fields are separated by commas, and enclosed in
* quotes if they contain commas or quotes.
* Embedded quotes are doubled.
* Embedded spaces do not normally require surrounding quotes.
* The last field on the line is not followed by a comma.
* Null fields are represented by two commas in a row.
* We ignore leading and trailing spaces on fields, even inside quotes.
*
* @author copyright (c) 2002 Roedy Green Canadian Mind Products
* Roedy posted this code on Newsgroups:comp.lang.java.programmer on 27th March 2002.
*
* Heinrich added some stuff like comment ability and linewise working.
*
*/
public class CSVReader {
/**
* Constructor
*
* @param r input Reader source of CSV Fields to read.
* @param separator
* field separator character, usually ',' in North America,
* ';' in Europe and sometimes '\t' for tab.
*/
public CSVReader (Reader r, char separator) {
/* convert Reader to BufferedReader if necessary */
if ( r instanceof BufferedReader ) {
this.r = (BufferedReader) r;
} else {
this.r = new BufferedReader(r);
}
this.separator = separator;
} // end of CSVReader
/**
* Constructor with default field separator ','.
*
* @param r input Reader source of CSV Fields to read.
*/
public CSVReader (Reader r) {
/* convert Reader to BufferedReader if necessary */
if ( r instanceof BufferedReader ) {
this.r = (BufferedReader) r;
} else {
this.r = new BufferedReader(r);
}
this.separator = ',';
} // end of CSVReader
private static final boolean debugging = true;
/**
* Reader source of the CSV fields to be read.
*/
private BufferedReader r;
/*
* field separator character, usually ',' in North America,
* ';' in Europe and sometimes '\t' for tab.
*/
private char separator;
/**
* category of end of line char.
*/
private static final int EOL = 0;
/**
* category of ordinary character
*/
private static final int ORDINARY = 1;
/**
* categotory of the quote mark "
*/
private static final int QUOTE = 2;
/**
* category of the separator, e.g. comma, semicolon
* or tab.
*/
private static final int SEPARATOR = 3;
/**
* category of characters treated as white space.
*/
private static final int WHITESPACE = 4;
/**
* categorise a character for the finite state machine.
*
* @param c the character to categorise
* @return integer representing the character's category.
*/
private int categorise ( char c ) {
switch ( c ) {
case ' ':
case '\r':
case 0xff:
return WHITESPACE;
// case ';':
// case '!':
case '#':
//return EOL;
case '\n':
return EOL; /* artificially applied to end of line */
case '\"':
return QUOTE;
default:
if (c == separator) {
/* dynamically determined so can't use as case label */
return SEPARATOR;
} else if ( '!' <= c && c <= '~' ) {
/* do our tests in crafted order, hoping for an early return */
return ORDINARY;
} else if ( 0x00 <= c && c <= 0x20 ) {
return WHITESPACE;
} else if ( Character.isWhitespace(c) ) {
return WHITESPACE;
} else {
return ORDINARY;
}
} // end of switch
} // end of categorise
/**
* parser: We are in blanks before the field.
*/
private static final int SEEKINGSTART = 0;
/**
* parser: We are in the middle of an ordinary field.
*/
private static final int INPLAIN = 1;
/**
* parser: e are in middle of field surrounded in quotes.
*/
private static final int INQUOTED = 2;
/**
* parser: We have just hit a quote, might be doubled
* or might be last one.
*/
private static final int AFTERENDQUOTE = 3;
/**
* parser: We are in blanks after the field looking for the separator
*/
private static final int SKIPPINGTAIL = 4;
/**
* state of the parser's finite state automaton.
*/
/**
* The line we are parsing.
* null means none read yet.
* Line contains unprocessed chars. Processed ones are removed.
*/
private String line = null;
/**
* How many lines we have read so far.
* Used in error messages.
*/
private int lineCount = 0;
public String[] getLine() {
Vector lineArray = new Vector();
String token = null;
String returnArray [] = null;
// reading values from line until null comes
try {
while (lineArray.size() == 0) {
while ( (token = get() ) != null ) {
lineArray.add(token);
} // end of while
} // end of while
} catch (EOFException e) {
return null;
} catch (IOException e) {
}
returnArray = new String[lineArray.size()];
for(int ii=0; ii < lineArray.size(); ii++) {
returnArray[ii] = lineArray.elementAt(ii).toString();
} // end of for
return returnArray;
}
/**
* Read one field from the CSV file
*
* @return String value, even if the field is numeric. Surrounded
* and embedded double quotes are stripped.
* possibly "". null means end of line.
*
* @exception EOFException
* at end of file after all the fields have
* been read.
*
* @exception IOException
* Some problem reading the file, possibly malformed data.
*/
private String get() throws EOFException, IOException {
StringBuffer field = new StringBuffer(50);
/* we implement the parser as a finite state automaton with five states. */
readLine();
int state = SEEKINGSTART; /* start seeking, even if partway through a line */
/* don't need to maintain state between fields. */
/* loop for each char in the line to find a field */
/* guaranteed to leave early by hitting EOL */
for ( int i=0; i<line.length(); i++ ) {
char c = line.charAt(i);
int category = categorise(c);
switch ( state ) {
case SEEKINGSTART: {
/* in blanks before field */
switch ( category ) {
case WHITESPACE:
/* ignore */
break;
case QUOTE:
state = INQUOTED;
break;
case SEPARATOR:
/* end of empty field */
line = line.substring(i+1);
return "";
case EOL:
/* end of line */
line = null;
return null;
case ORDINARY:
field.append(c);
state = INPLAIN;
break;
}
break;
} // end of SEEKINGSTART
case INPLAIN: {
/* in middle of ordinary field */
switch ( category ) {
case QUOTE:
throw new IOException("Malformed CSV stream. Missing quote at start of field on line " + lineCount);
case SEPARATOR:
/* done */
line = line.substring(i+1);
return field.toString().trim();
case EOL:
line = line.substring(i); /* push EOL back */
return field.toString().trim();
case WHITESPACE:
field.append(' ');
break;
case ORDINARY:
field.append(c);
break;
}
break;
} // end of INPLAIN
case INQUOTED: {
/* in middle of field surrounded in quotes */
switch ( category ) {
case QUOTE:
state = AFTERENDQUOTE;
break;
case EOL:
throw new IOException ("Malformed CSV stream. Missing quote after field on line "+lineCount);
case WHITESPACE:
field.append(' ');
break;
case SEPARATOR:
case ORDINARY:
field.append(c);
break;
}
break;
} // end of INQUOTED
case AFTERENDQUOTE: {
/* In situation like this "xxx" which may
turn out to be xxx""xxx" or "xxx",
We find out here. */
switch ( category ) {
case QUOTE:
field.append(c);
state = INQUOTED;
break;
case SEPARATOR :
/* we are done.*/
line = line.substring(i+1);
return field.toString().trim();
case EOL:
line = line.substring(i); /* push back eol */
return field.toString().trim();
case WHITESPACE:
/* ignore trailing spaces up to separator */
state = SKIPPINGTAIL;
break;
case ORDINARY:
throw new IOException("Malformed CSV stream, missing separator after field on line " + lineCount);
}
break;
} // end of AFTERENDQUOTE
case SKIPPINGTAIL: {
/* in spaces after field seeking separator */
switch ( category ) {
case SEPARATOR :
/* we are done.*/
line = line.substring(i+1);
return field.toString().trim();
case EOL:
line = line.substring(i); /* push back eol */
return field.toString().trim();
case WHITESPACE:
/* ignore trailing spaces up to separator */
break;
case QUOTE:
case ORDINARY:
throw new IOException("Malformed CSV stream, missing separator after field on line " + lineCount);
} // end of switch
break;
} // end of SKIPPINGTAIL
} // end switch(state)
} // end for
throw new IOException("Program logic bug. Should not reach here. Processing line " + lineCount);
} // end get
/**
* Make sure a line is available for parsing.
* Does nothing if there already is one.
*
* @exception EOFException
*/
private void readLine() throws EOFException, IOException {
if ( line == null ) {
line = r.readLine(); /* this strips platform specific line ending */
if ( line == null ) {
/* null means EOF, yet another inconsistent Java convention. */
throw new EOFException();
} else {
line += '\n'; /* apply standard line end for parser to find */
lineCount++;
}
}
} // end of readLine
/**
* Skip over fields you don't want to process.
*
* @param fields How many field you want to bypass reading.
* The newline counts as one field.
* @exception EOFException
* at end of file after all the fields have
* been read.
* @exception IOException
* Some problem reading the file, possibly malformed data.
*/
public void skip(int fields) throws EOFException, IOException {
if ( fields <= 0 ) {
return;
}
for ( int i=0; i<fields; i++ ) {
// throw results away
get();
}
} // end of skip
/**
* Skip over remaining fields on this line you don't want to process.
*
* @exception EOFException
* at end of file after all the fields have
* been read.
* @exception IOException
* Some problem reading the file, possibly malformed data.
*/
public void skipToNextLine() throws EOFException, IOException {
if ( line == null ) {
readLine();
}
line = null;
} // end of skipToNextLine
/**
* Close the Reader.
*/
public void close() throws IOException {
if ( r != null ) {
r.close();
r = null;
}
} // end of close
/**
* @param args [0]: The name of the file.
*/
private static void testSingleTokens(String[] args) {
if ( debugging ) {
try {
// read test file
CSVReader csv = new CSVReader(new FileReader(args[0]), ',');
try {
while ( true ) {
System.out.println(csv.get());
}
} catch ( EOFException e ) {
}
csv.close();
} catch ( IOException e ) {
e.printStackTrace();
System.out.println(e.getMessage());
}
} // end if
} // end of testSingleTokens
/**
* @param args [0]: The name of the file.
*/
private static void testLines(String[] args) {
int lineCounter = 0;
String loadLine[] = null;
String DEL = ",";
if ( debugging ) {
try {
// read test file
CSVReader csv = new CSVReader(new FileReader(args[0]), ',');
while( (loadLine = csv.getLine()) != null) {
lineCounter++;
StringBuffer logBuffer = new StringBuffer();
String logLine;
//log.debug("#" + lineCounter +" : '" + loadLine.length + "'");
logBuffer.append(loadLine[0]); // write first token, then write DEL in loop and the whole rest.
for(int i=1; i < loadLine.length; i++) {
logBuffer.append(DEL).append(loadLine[i]);
}
logLine = logBuffer.toString();
logLine.substring(0, logLine.lastIndexOf(DEL));
//logLine.delete(logLine.lastIndexOf(DEL), logLine.length()); // is supported since JDK 1.4
//System.out.println("#" + lineCounter +" : '" + loadLine.length + "' " + logLine);
System.out.println(logLine);
} // end of while
csv.close();
} catch ( IOException e ) {
e.printStackTrace();
System.out.println(e.getMessage());
}
} // end if
} // end of testLines
/**
* Test driver
*
* @param args [0]: The name of the file.
*/
static public void main(String[] args) {
//testSingleTokens(args);
testLines(args);
} // end main
} // end CSVReader
// end of file
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