1

Hi have written controller class like below. I am trying to get file from mongo db and try to download it.

    organizationFileAttachmentService.setUser(getUser());
    GridFSDBFile file = organizationFileAttachmentService.getGridFSDBFileById(new ObjectId(id), "File");
    if (file != null) {
        byte[] content = organizationFileAttachmentService.findByIdAndBucket(new ObjectId(id), "File");
        try {
            int size = content.length;
            InputStream is = null;
            byte[] b = new byte[size];
            try {
                is = new ByteArrayInputStream(content);
                is.read(b);
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (is != null)
                        is.close();
                } catch (Exception ex) {

                }
            }
            response.setContentType(file.getContentType());
            // String attachment =
            // "attachment; filename=\""+file.getFilename()+"\"";
            String attachment = "attachment; filename=" + file.getFilename();
            // response.setContentLength(new
            // Long(file.getLength()).intValue());
            response.setCharacterEncoding(file.getMD5());
            response.setHeader("content-Disposition", attachment);// "attachment;filename=test.xls"
            // copy it to response's OutputStream
            // FileCopyUtils.copy(is, response.getOutputStream());
            IOUtils.copy(is, response.getOutputStream());
            response.flushBuffer();
            is.close();
        } catch (IOException ex) {
            _logger.info("Error writing file to output stream. Filename was '" + id + "'");
            throw new RuntimeException("IOError writing file to output stream");
        }

but i am not able to down load file. can any one help me.

4

2 回答 2

4

如果您错过了它，Spring 提供了各种内置的资源处理程序。

http://docs.spring.io/spring/docs/3.2.5.RELEASE/spring-framework-reference/html/resources.html#resources-implementations

如果您的方法返回其中之一（在您的情况下可能是 ByteArrayResource），那么您只需要在接口上添加几个注释，如下所示：

@RequestMapping(value = "/foo/bar/{fileId}", 
    method = RequestMethod.GET, 
    produces = { MediaType.APPLICATION_OCTET_STREAM_VALUE })
@ResponseBody FileSystemResource downloadFile(Long fileId);

这样就不用为您摆弄编码和标头了。我建议在自己动手之前尝试一下。

编辑：以上在 Spring 3.1.4 中运行良好。它不再适用于 3.2.x 或 4.x。以前，produces = { MediaType.APPLICATION_OCTET_STREAM_VALUE } 会导致 Spring 添加适当的标头，现在它将其视为限制。如果使用标准 Web 浏览器访问 URL，则不会发送“application/octet-stream”的接受标头。因此 Spring 将返回 406 错误。为了让它再次工作，需要在没有“produces”属性的情况下重新编写这样的方法。相反，将 HttpServletResponse 添加到方法参数并在方法内添加标头。IE：

@RequestMapping(value = "/foo/bar/{fileId}", 
    method = RequestMethod.GET)
@ResponseBody FileSystemResource downloadFile(
            Long fileId, HttpServletResponse response) {
    ...
    response.setHeader( "Content-Disposition", "attachment;filename=" + fileName );
    ...
}

编辑 redux：现在通过 Spring Boot 1.1.8 使用 Spring 4.0.7。看来设置produces = { MediaType.APPLICATION_OCTET_STREAM_VALUE }指令现在又可以工作了。对于我尝试过的所有浏览器来说，只要有这个指令似乎就足够了。但是请注意，我还发现它没有设置Content-Disposition，保留为application/json. 虽然这对于浏览器来说似乎不是问题，但我在 PHP 客户端应用程序中遇到了一些错误，这些错误似乎仅基于Content-Disposition. 所以看来目前的解决方案是做到以上两点！

于 2013-11-09T17:51:58.520 回答
1

我已将我的请求更改为 GET 并在 html 的锚标记中添加了请求。Aslo 将我的代码更改为

@RequestMapping(value = "/getFileById/{id}", method = RequestMethod.GET)
public @ResponseBody
void download(@PathVariable String id, HttpServletRequest request, HttpServletResponse response) throws IOException {
    organizationFileAttachmentService.setUser(getUser());
    GridFSDBFile file = organizationFileAttachmentService.getGridFSDBFileById(new ObjectId(id), "File");
    if (file != null) {
        try {
            response.setContentType(file.getContentType());
            response.setContentLength((new Long(file.getLength()).intValue()));
            response.setHeader("content-Disposition", "attachment; filename=" + file.getFilename());// "attachment;filename=test.xls"
            // copy it to response's OutputStream
            IOUtils.copyLarge(file.getInputStream(), response.getOutputStream());
        } catch (IOException ex) {
            _logger.info("Error writing file to output stream. Filename was '" + id + "'");
            throw new RuntimeException("IOError writing file to output stream");
        }
    }
}

现在它对我来说工作正常。

于 2013-11-14T14:41:06.767 回答