Download created file csv

Question

I am creating a file csv with opencsv library, but I have some little difficulties. I followed a tutorial on line:

private void exportProducts() {

    String OBJECT_LIST_SAMPLE = "C:/tmp/object-list-sample.csv";

     try (
             BufferedWriter  writer = Files.newBufferedWriter(Paths.get(OBJECT_LIST_SAMPLE));

                CSVWriter csvWriter = new CSVWriter(writer,
                        CSVWriter.DEFAULT_SEPARATOR,
                        CSVWriter.NO_QUOTE_CHARACTER,
                        CSVWriter.DEFAULT_ESCAPE_CHARACTER,
                        CSVWriter.DEFAULT_LINE_END);
            ) {
                String[] headerRecord = {"Name", "Email", "Phone", "Country"};
                csvWriter.writeNext(headerRecord);

                csvWriter.writeNext(new String[]{"Sundar Pichai ♥", "sundar.pichai@gmail.com", "+1-1111111111", "India"});
                csvWriter.writeNext(new String[]{"Satya Nadella", "satya.nadella@outlook.com", "+1-1111111112", "India"});

            } catch (IOException e) {
                LOG.error("", e);
            }

}

All good, the file is created correctly, but I want extend this one. I mean

1. I don't want use OBJECT_LIST_SAMPLE , but I want create a temp file (File.creteTempFile), use it to write the strings
2. In the end, I want download directly this file, for the user.

Please help me!

Thanks

Answer 1

How to create a BufferedWriter on a temporary file using Files.createTempFile

Path tempDir = Files.createTempFile("Products", "sample.csv");
BufferedWriter writer = Files.newBufferedWriter(tempDir, StandardOpenOption.DELETE_ON_CLOSE);

Here is a quick example :

public static void main(String[] args) throws Exception {
    Path p = Files.createTempFile("Test", ".tmp");
    try(
            BufferedWriter writer = Files.newBufferedWriter(p, StandardOpenOption.DELETE_ON_CLOSE)
            ){
        System.out.println(p);
        for(int i = 0; i < 26; ++i){
            writer.append((char)(i+'a'));
        }

    }
}

Creating a "c:\Temp\Test#########.tmp" containing :

 abcdefghijklmnopqrstuvwxyz

For the second part, there is not enough information.