java文件在浏览器下载和预览

  @ApiOperation(value = "文件下载")
    @ApiImplicitParam(name = "fileId", value = "文件fileId", required = true)
    @GetMapping(value = "/download/{fileId}")
    public Result download(@PathVariable String fileId) throws Exception {
        FileInfo fileInfo = fileInfoService.getFileById(fileId);
        if (fileInfo == null) {
            return Result.failure(ResultCode.DATA_IS_WRONG);
        }
        String userAgent = request.getHeader("User-Agent");
        String fileName = fileInfo.getFileName() + "." + fileInfo.getFileSuffix();
        if (userAgent != null && (userAgent.contains("MSIE") || userAgent.contains("Trident"))) {
            fileName = URLEncoder.encode(fileName, "UTF-8");
        } else {
            fileName = new String(fileName.getBytes(StandardCharsets.UTF_8), StandardCharsets.ISO_8859_1);
        }
        response.setHeader("Content-Disposition", String.format("attachment; fileName="%s"", fileName));
        response.setHeader("Content-Length", Long.toString(fileInfo.getFileSize()));
        response.setCharacterEncoding("UTF-8");
        FileInputStram io = new FileInputStream(new File(fileInfo.getStorePath()));
        IOUtils.copy(io, response.getOutputStream());
        return null;
    }




 @ApiOperation(value = "文件预览")
    @ApiImplicitParam(name = "fileId", value = "文件fileId", required = true)
    @RequestMapping(value = "/preview/{fileId}", method = RequestMethod.GET)
    public void downLoad1(@PathVariable String fileId) throws Exception {
        FileInfo fileInfo = fileInfoService.getFileById(fileId);
        if (fileInfo == null) {
            return;
        }
        try {
            Path path = Paths.get("." + fileInfo.getFileSuffix());
            response.setContentType(Files.probeContentType(path));
        } catch (IOException e) {
            response.setContentType("application/octet-stream");
        }
        response.setCharacterEncoding("UTF-8");

        FileInputStram io = new FileInputStream(new File(fileInfo.getStorePath()));
        IOUtils.copy(io, response.getOutputStream());
    }