如何使用反斜杠符号解析或清理传入的 csv 条目？

Question

I have a requirement to parse external CSV files and read their name attributes. I am using opencsv library to achieve this, please find the test code below. It works pretty well with valid CSV files, however, if one of the rows is invalid, there is no way to handle that error. I shared an example CSV below with an error case, inside which the escaped double quote is causing the problem in java. Could we somehow parse this inline or at the file level and replace \" with " .

    @Test
    public void csvTest() throws IOException {
        String fileName = "ERROR.csv";
        File file = new File("D:\\csvFiles\\" + fileName);
        if (file.exists()) {

            CSVReader csvReader = new CSVReader(new FileReader("D:\\csvFiles\\" + fileName));
            String[] nextLine;
            int row = 0;
            while ((nextLine = csvReader.readNext()) != null) {
                row++;
                if (nextLine.length > 0) {
                    System.out.println("ROW: " + row + " " + String.join(",", nextLine));
                }
            }

        }
    } 

ERROR.csv

id,name,address,phone
"1","Bob","New Jersey","9999999999"
"2","Smith","Sydney ///\","9999999999"

Note: When we open this csv file in the excel app, then it renders perfectly, so is it only in the java world that is treating it erroneously, because a double quote has been escaped with the preceding backslash ( \" )?

Answer 1

A customized CSVReader instance works for me; see code below:

CSVParserBuilder pb = new CSVParserBuilder();
CSVParser p = pb.withIgnoreLeadingWhiteSpace(true)
        .withEscapeChar('%')
        .withSeparator(',')
        .build();
CSVReaderBuilder rb = new CSVReaderBuilder(new FileReader(file));
rb.withCSVParser(p);
CSVReader csvReader = rb.build();

String[] nextLine;
int row = 0;
while ((nextLine = csvReader.readNext()) != null) {
  row++;
  if (nextLine.length > 0) {
    System.out.println("ROW: " + row + " " + String.join(",", nextLine));
  }
}

Note: I set a different escape character with .withEscapeChar('%') . You could choose any special character different from \ of which you know that it has no actual meaning in your data.

Given such a customized CSVParser , the configured CSVReader instance works just fine with your csv data provided in the OP.

It produces

ROW: 1 id,name,address,phone
ROW: 2 1,Bob,New Jersey,9999999999
ROW: 3 2,Smith,Sydney ///\,9999999999

as (expected) output without any errors.

I used OpenCSV in version 5.7.x