如何将 xlsx 文件转换为 csv？

目前我正在使用下面的代码使用 Java 将 XLSX 文件转换为 CSV。我需要一个更快的解决方案，因为这太慢了。

public class Test1 {
    static void convert(File inputFile, File outputFile) {
        try {
            FileOutputStream fos = new FileOutputStream(outputFile);
            // Get the workbook object for XLSX file
            XSSFWorkbook wBook = new XSSFWorkbook(
                    new FileInputStream(inputFile));
            // Get first sheet from the workbook
            XSSFSheet sheet = wBook.getSheetAt(0);
            Row row;
            Cell cell;
            // Iterate through each rows from first sheet
            Iterator<Row> rowIterator = sheet.iterator();

            while (rowIterator.hasNext()) {
                row = rowIterator.next();

                // For each row, iterate through each columns
                Iterator<Cell> cellIterator = row.cellIterator();
                while (cellIterator.hasNext()) {

                    cell = cellIterator.next();

                    switch (cell.getCellType()) {
                    case Cell.CELL_TYPE_BOOLEAN:
                        data.append(cell.getBooleanCellValue() + ",");

                        break;
                    case Cell.CELL_TYPE_NUMERIC:
                        data.append(cell.getNumericCellValue() + ",");

                        break;
                    case Cell.CELL_TYPE_STRING:
                        data.append(cell.getStringCellValue() + ",");
                        break;

                    case Cell.CELL_TYPE_BLANK:
                        data.append("" + ",");
                        break;
                    default:
                        data.append(cell + ",");

                    }
                }
            }

            fos.write(data.toString().getBytes());
            fos.close();

        } catch (Exception ioe) {
            ioe.printStackTrace();
        }
    }

    // testing the application

    public static void main(String[] args) {
        // reading file from desktop
        File inputFile = new File("D:\\Test.xlsx");
        // writing excel data to csv
        File outputFile = new File("D:\\Test1.csv");
        convert(inputFile, outputFile);
    }
}

The 文本提取器 https://poi.apache.org/apidocs/5.0/org/apache/poi/xssf/extractor/package-summary.html将转储整个工作簿的 TSV。性能取决于所选的实现和您的内存可用性。

然后你可以将其通过管道传输到CSVPrinter https://commons.apache.org/proper/commons-csv/apidocs/org/apache/commons/csv/CSVPrinter.html获得正确的 CSV 输出。我不认为 Excel 单元格可以包含制表符，所以这应该是安全的。如果您的单元格中有换行符，我不确定 TSV 输出是否有效，但如果是，您可以使用CSVParser https://commons.apache.org/proper/commons-csv/apidocs/org/apache/commons/csv/CSVParser.html阅读它而不是lines().

XSSFWorkbook input = new XSSFWorkbook(new File("input.xlsx"));
CSVPrinter output = new CSVPrinter(new FileWriter("output.csv"), CSVFormat.DEFAULT); 

String tsv = new XSSFExcelExtractor(input).getText();
BufferedReader reader = new BufferedReader(new StringReader(tsv));
reader.lines().map(line -> line.split("\t").forEach(output::printRecord);

如果将整个缓冲作为String效率太低了，复制基于事件的提取器之一的实现并直接写入CSVPrinter反而。