1. 匯出檔案工具類

@Slf4j
public class ExportUtil {

    /** CSV檔案列分隔符 */
    private static final String CSV_COLUMN_SEPARATOR = ",";

    /** CSV檔案列分隔符 */
    private static final String CSV_RN = "\r\n";

    /**
     *
     * @param dataList 集合資料
     * @param colNames 表頭部資料
     * @param mapKey 查詢的對應資料
     * @param
 
 os 返回結果
     */
    public static boolean doExport(List<Map<String, Object>> dataList, String colNames, String mapKey, OutputStream os) {
        try {
            StringBuffer buf = new StringBuffer();

            String[] colNamesArr = null;
            String[] mapKeyArr = null;

            colNamesArr = colNames.split(","
 
);
            mapKeyArr = mapKey.split(",");

            // 完成資料csv檔案的封裝
            // 輸出列頭
            for (String aColNamesArr : colNamesArr) {
                buf.append(aColNamesArr).append(CSV_COLUMN_SEPARATOR);
            }
            buf.append(CSV_RN);

            if (null != dataList) { // 輸出資料
 

                for (Map<String, Object> aDataList : dataList) {
                    for (String aMapKeyArr : mapKeyArr) {
                        buf.append(aDataList.get(aMapKeyArr)).append(CSV_COLUMN_SEPARATOR);
                    }
                    buf.append(CSV_RN);
                }
            }
            // 寫出響應
            os.write(buf.toString().getBytes("GBK"));
            os.flush();
            return true;
        } catch (Exception e) {
            log.error("doExport錯誤...", e);
        }
        return false;
    }

    /**
     * setHeader
     */
    public static void responseSetProperties(String fileName, HttpServletResponse response) throws UnsupportedEncodingException {
        // 設定檔案字尾
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
        String fn = fileName + sdf.format(new Date()) + ".csv";
        // 讀取字元編碼
        String utf = "UTF-8";

        // 設定響應
        response.setContentType("application/ms-txt.numberformat:@");
        response.setCharacterEncoding(utf);
        response.setHeader("Pragma", "public");
        response.setHeader("Cache-Control", "max-age=30");
        response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(fn, utf));
    }

}

2.Controller介面

@RestController
@RequestMapping("/test")
@Slf4j
public class DownloadFileController {

    @Autowired
    private SysLogService sysLogService;

    @GetMapping("/file")
    public Result download(HttpServletResponse response) {
        List<Map<String, Object>> dataList = null;

        List<SysLog> logList = sysLogService.findAll();// 查詢到要匯出的資訊

        if (logList.size() == 0) {
            ResultUtil.failure("無資料匯出");
        }
        String sTitle = "id,使用者名稱,操作型別,操作方法,建立時間";
        String fName = "log_";
        String mapKey = "id,username,operation,method,createDate";
        dataList = new ArrayList<>();
        Map<String, Object> map = null;
        for (SysLog order : logList) {
            map = new HashMap<>();

            map.put("id", order.getId());
            map.put("username", order.getUsername());
            map.put("operation", order.getOperation());
            map.put("method", order.getMethod());
            map.put("createDate", DateFormatUtils.format(order.getCreateDate(), "yyyy/MM/dd HH:mm"));

            dataList.add(map);
        }
        try (final OutputStream os = response.getOutputStream()) {
            ExportUtil.responseSetProperties(fName, response);
            ExportUtil.doExport(dataList, sTitle, mapKey, os);
            return null;
        } catch (Exception e) {
            log.error("生成csv檔案失敗", e);
        }
        return ResultUtil.failure("資料匯出出錯");
    }
}

3.測試

瀏覽器直接請求，可看到檔案下載，Excel可直接開啟檔案。