Spring REST-损坏/空白文件正在下载

小编典典

Spring REST-损坏/空白文件正在下载

spring-boot

我正在尝试创建一个端点来渲染/提供PDF文件。我已经通过以下链接构建了API，但是仍然面临一些问题。

以下是我的代码：

byte[] targetArray = null;

InputStream is = null;

InputStream objectData = object.getObjectContent();

BufferedReader reader = new BufferedReader(new InputStreamReader(objectData));

char[] charArray = new char[8 * 1024];
StringBuilder builder = new StringBuilder();
int numCharsRead;
while ((numCharsRead = reader.read(charArray, 0, charArray.length)) != -1) {

    builder.append(charArray, 0, numCharsRead);
}
reader.close();

objectData.close();
object.close();
targetArray = builder.toString().getBytes();

is = new ByteArrayInputStream(targetArray);


return ResponseEntity.ok().contentLength(targetArray.length).contentType(MediaType.APPLICATION_PDF)
                .cacheControl(CacheControl.noCache()).header("Content-Disposition", "attachment; filename=" + "testing.pdf")
                .body(new InputStreamResource(is));

当我使用邮递员访问API时，我可以下载PDF文件，但问题是它完全空白。可能是什么问题？

阅读 443

2020-05-30

共1个答案

小编典典

从服务器下载文件的方法有多种
，可以使用ResponseEntity<InputStreamResource>，。HttpServletResponse以下是两种下载方法。

@GetMapping("/download1")
       public ResponseEntity<InputStreamResource> downloadFile1() throws IOException {

          File file = new File(FILE_PATH);
          InputStreamResource resource = new InputStreamResource(new FileInputStream(file));

          return ResponseEntity.ok()
                .header(HttpHeaders.CONTENT_DISPOSITION,
                      "attachment;filename=" + file.getName())
                .contentType(MediaType.APPLICATION_PDF).contentLength(file.length())
                .body(resource);
       }

要么

您可以StreamingResponseBody用来下载大
文件。在这种情况下，服务器同时将数据写入OutputStream浏览器读取的数据，这意味着它是并行的。

@RequestMapping(value = "downloadFile", method = RequestMethod.GET)
    public StreamingResponseBody getSteamingFile(HttpServletResponse response) throws IOException {
        response.setContentType("application/pdf");
        response.setHeader("Content-Disposition", "attachment; filename=\"demo.pdf\"");
        InputStream inputStream = new FileInputStream(new File("C:\\demo-file.pdf"));
        return outputStream -> {
            int nRead;
            byte[] data = new byte[1024];
            while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
                System.out.println("Writing some bytes..");
                outputStream.write(data, 0, nRead);
            }
        };
    }

2020-05-30