How to download csv file using spring boot controller with contents?

Question

I am facing the issue while downloading the csv file. I have created get api in spring boot and wanted to download the file through that api. Here is my code.

@GetMapping(value = "/citydetails/download")
public ResponseEntity<Object> getCityDetails() throws IOException {
    System.out.println("Starting the rest call.");
    FileWriter filewriter = null;
    service = new LocalityService();
    try {
        List<CityDetails> details = service.getCityDetailsList();
        if (details.isEmpty()) {
            System.out.println("List is empty.");
        }
        StringBuilder fileContent = new StringBuilder("STATE,DISTRICT,CITY,VILLAGE,PIN\n");
        for (CityDetails data : details)
            fileContent.append(data.getStatename()).append(data.getDistrict()).append(data.getCity())
                    .append(data.getVillage()).append(data.getPindode());

        XSSFWorkbook workbook = service.saveFileContents(details);
        String filename = "C:\\Users\\" + System.getProperty("user.name") + "\\Downloads\\cityDetails.csv";
        FileOutputStream out = new FileOutputStream(filename);
        File file = new File("cityDetails.csv");
        workbook.write(out);
        out = new FileOutputStream(file);


        return ResponseEntity.ok()
                .contentType(MediaType.parseMediaType("text/csv"))
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + "cityDetails.csv" + "\"")
                .body(file);
    } catch (Exception ex) {
        System.out.println("Failed to execute rest" + ex.getStackTrace() + "Locale: " + ex.getLocalizedMessage());
        ErrorDetails errorDetails = new ErrorDetails(new Date(), ex.getMessage(), "false");
        return new ResponseEntity<>(errorDetails, HttpStatus.INTERNAL_SERVER_ERROR);
    } finally {
        if (filewriter != null)
            filewriter.close();
    }
}

Exception:

Here i have used XSSFWorkbook to save my content to csv. Now i wanted to download the csv file through Rest api which will contain the data.I have tried multiple ways but i am getting empty file.With the above code it will save the csv file in download folder in windows machine, but i want this api to work on every system so I wanted to download the csv file with contents instead of saving it to specific location. I am facing the issue, how to resolve that?

Answer 1

HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet=wkb.createSheet("sheet1");
HSSFRow row1=sheet.createRow(0);
HSSFCell cell=row1.createCell(0);
cell.setCellValue("table_demo");
sheet.addMergedRegion(new CellRangeAddress(0,0,0,3));

//input Excel date
HSSFRow row2=sheet.createRow(1);    
row2.createCell(0).setCellValue("name");
row2.createCell(1).setCellValue("class");    
row2.createCell(2).setCellValue("score_1");
row2.createCell(3).setCellValue("score_2");    
HSSFRow row3=sheet.createRow(2);
row3.createCell(0).setCellValue("Jeams");
row3.createCell(1).setCellValue("High 3");
row3.createCell(2).setCellValue(87);    
row3.createCell(3).setCellValue(78);    

//output Excel file
OutputStream output=response.getOutputStream();
response.reset();
response.setHeader("Content-disposition", "attachment; filename=details.xls");
response.setContentType("application/msexcel");        
wkb.write(output);
output.close();

This code can get a simple excel file

Answer 2

//image @GetMapping(value = "/image") public @ResponseBody byte[] getImage() throws IOException { InputStream in = getClass() .getResourceAsStream("/com/baeldung/produceimage/image.jpg"); return IOUtils.toByteArray(in); } //normal file @GetMapping( value = "/get-file", produces = MediaType.APPLICATION_OCTET_STREAM_VALUE ) public @ResponseBody byte[] getFile() throws IOException { InputStream in = getClass() .getResourceAsStream("/com/baeldung/produceimage/data.txt"); return IOUtils.toByteArray(in); }

Answer 3

Create the rest endpoint to generate the CSV File and to extract data from database using JPA repository.

You can set the setContentType into response and set Header with file name and with file type as csv.

 @GetMapping("/csv")
public void employeeDetailsReport(HttpServletResponse response) throws IOException {

    Random random = new Random();
    String fileType = "attachment; filename=employee_details_" + random.nextInt(1000) + ".csv";
    response.setHeader("Content-Disposition", fileType);
    response.setContentType("text/csv");

    CSVWriterUtility.employeeDetailReport(response,
            employeeRepository.findAll());
}

I have referred this code from the Spring Boot CSV Example .

There are many libraries available with that we can read/write data to csv. One of the open source library is Super CSV.

An open-source library called Super CSV offers ways for reading and writing headers as needed.

1. Data formatting options provided by SuperCSV, which enable cutting and regex replacements while processing, make parsing simpler.
2. The Library can be used in systems with low memory and performance because it also supports stream-based input and output.
3. The other CSV parsers do not support partial reading or partial writing, but the SuperCSV library does.
4. The user has the option to write a dataset with optional values without adding their own error-handling, or to set selected header column values to null and continue processing the other columns.