读取Java中的CSV文件

Question

I wrote a programm that reads a csv file and puts it into a TableModel. My problem is that I want to expand the programm so, that if the csv file gets changes from outside my tablemodel gets updated and gets the new values.

I would now programm a scheduler so that the thread sleeps for about a minute and checks it every minute if the timestamp of the file changed. If so it would read the file again. But i dont know what happens to the whole programm if i use a scheduler because this little software i write will be a part of a much much bigger software wich is running on JDK 6. So I search for a performant and independent from the bigger software solution to get the changes in the tablemodel.

Can someone help out?

Answer 1

java.nio.file package now contains the Watch Service API . This, effectively:

This API enables you to register a directory (or directories) with the watch service. When registering, you tell the service which types of events you are interested in: file creation, file deletion, or file modification. When the service detects an event of interest, it is forwarded to the registered process. The registered process has a thread (or a pool of threads) dedicated to watching for any events it has registered for. When an event comes in, it is handled as needed.

See reference here .

Oh! This API is only available from JDK 7 (onwards).

Answer 2

**OpenCsv is a best way to read csv file in java.
if your are using maven then you can use below dependency or download it's jar from web.**

 @SuppressWarnings({"rawtypes", "unchecked"})
  public void readCsvFile() {
    CSVReader csvReader;
    CsvToBean csv;
    File fileEntry; 
    try {
      fileEntry = new File("path of your file");
      csv = new CsvToBean();
      csvReader = new CSVReader(new FileReader(fileEntry), ',', '"', 1);
      List list = csv.parse(setColumMapping(), csvReader);
     //List of LabReportSampleData class
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  //Below function is used to map the your csv file to your mapping object. 
  //columns String array: The value inside your csv file. means 0 index map with degree variable in your mapping class.
  @SuppressWarnings({"rawtypes", "unchecked"})
  private static ColumnPositionMappingStrategy setColumMapping() {
    ColumnPositionMappingStrategy strategy = new ColumnPositionMappingStrategy();
    strategy.setType(LabReportSampleData.class);
    String[] columns =
        new String[] {"degree", "radian", "shearStress", "shearingStrain", "sourceUnit"};
    strategy.setColumnMapping(columns);
    return strategy;
  }