/**
 * @author BNTang
 */
@Slf4j
public class CsvUtils {
    private CsvUtils() {
    }

    /**
     * 导出csv文件
     *
     * @param response   response
     * @param fileName   文件名
     * @param fileHeader 表头
     * @param content    内容
     */
    public static void write(HttpServletResponse response, String fileName, final String[] fileHeader, List<List<String>> content) {
        try (OutputStream outputStream = getOutputStream(fileName, response);
             OutputStreamWriter outputStreamWriter = new OutputStreamWriter(Objects.requireNonNull(outputStream), "GBK")) {
            CSVPrinter csvPrinter = new CSVPrinter(outputStreamWriter, CSVFormat.DEFAULT.withHeader(fileHeader));
            for (List<String> element : content) {
                csvPrinter.printRecord(element);
            }
            csvPrinter.flush();
            csvPrinter.close();
        } catch (IOException e) {
            log.error("CSV文件写入失败");
        }
        log.info("CSV文件写入成功");
    }

    /**
     * 导出文件时为Writer生成OutputStream
     *
     * @param fileName 文件名
     * @param response {@link HttpServletResponse}
     * @return 输出流
     */
    private static OutputStream getOutputStream(String fileName, HttpServletResponse response) {
        try {
            fileName = URLEncoder.encode(fileName, "UTF-8");
            response.setContentType("application/octet-stream");
            response.setCharacterEncoding("UTF-8");
            response.setHeader("Content-Disposition", "attachment; filename=" + fileName + ".csv");
            return response.getOutputStream();
        } catch (Exception e) {
            log.error("导出失败");
        }
        return null;
    }
}