如何在 spring 启动中的 header 中设置文件大小以显示下载进度？

Question

How to set file size in the header in spring boot to display the download progress in the client?

@GetMapping(value = "/document/{nodeRef}/{versionNumber}")
public byte[] getDocumentWithVersion(@PathVariable(value = "nodeRef") UUID nodeRef, @PathVariable(value = "versionNumber") Double versionNumber) {
    return docService.getDocument(nodeRef, versionNumber);
}

Answer 1

The client receives the header before the file or the body starts the download. So added Content-length and content-type in the header .

@GetMapping(value = "/document/{nodeRef}/{versionNumber}")
public ResponseEntity<byte[]> getDocumentWithVersion(@PathVariable(value = "nodeRef") UUID nodeRef, @PathVariable(value = "versionNumber") Double versionNumber) {
    byte[] file = alfrescoService.getDocument(null, nodeRef, versionNumber);
    HttpHeaders headers = new HttpHeaders();
    headers.add(HttpHeaders.CONTENT_LENGTH, String.valueOf(file.length));
    headers.add(HttpHeaders.CONTENT_TYPE, "application/octet-stream");
    return ResponseEntity.ok().headers(headers).body(file);
}