CSV parsing with Commons CSV - Quotes within quotes causing IOException

问题

I am using Commons CSV to parse CSV content relating to TV shows. One of the shows has a show name which includes double quotes;

116,6,2,29 Sep 10,""JJ" (60 min)","http://www.tvmaze.com/episodes/4855/criminal-minds-6x02-jj"

The showname is "JJ" (60 min) which is already in double quotes. This is throwing an IOException java.io.IOException: (line 1) invalid char between encapsulated token and delimiter.

    ArrayList<String> allElements = new ArrayList<String>();
    CSVFormat csvFormat = CSVFormat.DEFAULT;
    CSVParser csvFileParser = new CSVParser(new StringReader(line), csvFormat);

    List<CSVRecord> csvRecords = null;

    csvRecords = csvFileParser.getRecords();

    for (CSVRecord record : csvRecords) {
        int length = record.size();
        for (int x = 0; x < length; x++) {
            allElements.add(record.get(x));
        }
    }

    csvFileParser.close();
    return allElements;

CSVFormat.DEFAULT already sets withQuote('"')

I think that this CSV is not properly formatted as ""JJ" (60 min)" should be """JJ"" (60 min)" - but is there a way to get commons CSV to handle this or do I need to fix this entry manually?

Additional information: Other show names contain spaces and commas within the CSV entry and are placed within double quotes.

回答1:

The problem here is that the quotes are not properly escaped. Your parser doesn't handle that. Try univocity-parsers as this is the only parser for java I know that can handle unescaped quotes inside a quoted value. It is also 4 times faster than Commons CSV. Try this code:

//configure the parser to handle your situation
CsvParserSettings settings = new CsvParserSettings();
settings.setUnescapedQuoteHandling(STOP_AT_CLOSING_QUOTE);

//create the parser
CsvParser parser = new CsvParser(settings);

//parse your line
String[] out = parser.parseLine("116,6,2,29 Sep 10,\"\"JJ\" (60 min)\",\"http://www.tvmaze.com/episodes/4855/criminal-minds-6x02-jj\"");

for(String e : out){
    System.out.println(e);
}

This will print:

116
6
2
29 Sep 10
"JJ" (60 min)
http://www.tvmaze.com/episodes/4855/criminal-minds-6x02-jj

Hope it helps.

Disclosure: I'm the author of this library, it's open source and free (Apache 2.0 license)

回答2:

You can use withEscape('\\') to ignore quotes within quotes

CSVFormat csvFormat = CSVFormat.DEFAULT.withEscape('\\')

Reference: https://commons.apache.org/proper/commons-csv/apidocs/org/apache/commons/csv/CSVFormat.html

回答3:

Quoting mainly allows for field to contain separator characters. If embedded quotes in a field are not escaped, this can't work, so there isn't any point in using quotes. If your example value was "JJ", 60 Min, how is a parser to know the comma is part of the field? The data format can't handle embedded commas reliably, so if you want to be able to do that, best to change the source to generate an RFC compliant csv format.

Otherwise, it looks like the data source is simply surrounding non-numeric fields with quotes, and separating each field a comma, so the parser needs to do the reverse. You should probably just treat the data as comma-delimited and strip the leading/trailing quotes yourself with removeStart/removeEnd.

You might use CSVFormat .withQuote(null), or forget about that and just use String .split(',')

回答4:

I think that having both quotations AND spaces in the same token is what confuses the parser. Try this:

CSVFormat csvFormat = CSVFormat.DEFAULT.withQuote('"').withQuote(' ');

That should fix it.

Example

For your input line:

String line = "116,6,2,29 Sep 10,\"\"JJ\" (60 min)\",\"http://www.tvmaze.com/episodes/4855/criminal-minds-6x02-jj\"";

Output is (and no exception is thrown):

[116, 6, 2, 29 Sep 10, ""JJ" (60 min)", "http://www.tvmaze.com/episodes/4855/criminal-minds-6x02-jj"]

来源：https://stackoverflow.com/questions/44697228/csv-parsing-with-commons-csv-quotes-within-quotes-causing-ioexception

标签

java

csv

double-quotes

apache-commons-csv