我正在尝试从Spring引导休息服务下载文件。
@RequestMapping(path="/downloadFile",method=RequestMethod.GET)
@Consumes(MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<InputStreamReader> downloadDocument(
String acquistionId,
String fileType,
Integer expressVfId) throws IOException {
File file2Upload = new File("C:\\Users\\admin\\Desktop\\bkp\\1.rtf");
HttpHeaders headers = new HttpHeaders();
headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
headers.add("Pragma", "no-cache");
headers.add("Expires", "0");
InputStreamReader i = new InputStreamReader(new FileInputStream(file2Upload));
System.out.println("The length of the file is : "+file2Upload.length());
return ResponseEntity.ok().headers(headers).contentLength(file2Upload.length())
.contentType(MediaType.parseMediaType("application/octet-stream"))
.body(i);
}
当我尝试从浏览器下载文件时,它会开始下载,但始终会失败。导致下载失败的服务有什么问题吗?
答案 0 :(得分:83)
选项1
给定Resource的InputStream实施。
只有在没有其他特定资源实施的情况下才能使用
适用。特别是,在可能的情况下,更喜欢ByteArrayResource或任何基于文件的资源实现。
@RequestMapping(path = "/download", method = RequestMethod.GET)
public ResponseEntity<Resource> download(String param) throws IOException {
// ...
InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
return ResponseEntity.ok()
.headers(headers)
.contentLength(file.length())
.contentType(MediaType.parseMediaType("application/octet-stream"))
.body(resource);
}
Option2 作为InputStreamResource的文档建议 - 使用ByteArrayResource:
@RequestMapping(path = "/download", method = RequestMethod.GET)
public ResponseEntity<Resource> download(String param) throws IOException {
// ...
Path path = Paths.get(file.getAbsolutePath());
ByteArrayResource resource = new ByteArrayResource(Files.readAllBytes(path));
return ResponseEntity.ok()
.headers(headers)
.contentLength(file.length())
.contentType(MediaType.parseMediaType("application/octet-stream"))
.body(resource);
}
答案 1 :(得分:5)
我建议使用 StreamingResponseBody ,因为有了它,应用程序可以直接写入响应(OutputStream),而无需占用Servlet容器线程。如果要下载很大的文件,这是个好方法。
@GetMapping("download")
public StreamingResponseBody downloadFile(HttpServletResponse response, @PathVariable Long fileId) {
FileInfo fileInfo = fileService.findFileInfo(fileId);
response.setContentType(fileInfo.getContentType());
response.setHeader(
HttpHeaders.CONTENT_DISPOSITION, "attachment;filename=\"" + fileInfo.getFilename() + "\"");
return outputStream -> {
int bytesRead;
byte[] buffer = new byte[BUFFER_SIZE];
InputStream inputStream = fileInfo.getInputStream();
while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
};
}
Ps .:使用 StreamingResponseBody 时,强烈建议配置Spring MVC中使用的TaskExecutor来执行异步请求。 TaskExecutor是一个接口,用于抽象Runnable的执行。
更多信息:https://medium.com/swlh/streaming-data-with-spring-boot-restful-web-service-87522511c071
答案 2 :(得分:2)
下面的示例代码对我有用,可能会对某人有所帮助。
import org.springframework.core.io.ByteArrayResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
@RestController
@RequestMapping("/app")
public class ImageResource {
private static final String EXTENSION = ".jpg";
private static final String SERVER_LOCATION = "/server/images";
@RequestMapping(path = "/download", method = RequestMethod.GET)
public ResponseEntity<Resource> download(@RequestParam("image") String image) throws IOException {
File file = new File(SERVER_LOCATION + File.separator + image + EXTENSION);
HttpHeaders header = new HttpHeaders();
header.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=img.jpg");
header.add("Cache-Control", "no-cache, no-store, must-revalidate");
header.add("Pragma", "no-cache");
header.add("Expires", "0");
Path path = Paths.get(file.getAbsolutePath());
ByteArrayResource resource = new ByteArrayResource(Files.readAllBytes(path));
return ResponseEntity.ok()
.headers(header)
.contentLength(file.length())
.contentType(MediaType.parseMediaType("application/octet-stream"))
.body(resource);
}
}
答案 3 :(得分:2)
我想分享一种使用JavaScript(ES6),反应和 Spring Boot 后端下载文件的简单方法:
- Spring boot Rest Controller
来自org.springframework.core.io.Resource的资源
@SneakyThrows
@GetMapping("/files/{filename:.+}/{extraVariable}")
@ResponseBody
public ResponseEntity<Resource> serveFile(@PathVariable String filename, @PathVariable String extraVariable) {
Resource file = storageService.loadAsResource(filename, extraVariable);
return ResponseEntity.ok()
.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + file.getFilename() + "\"")
.body(file);
}
- 使用AXIOS 反应
将responseType设置为arraybuffer,以指定响应中包含的数据类型。
export const DownloadFile = (filename, extraVariable) => {
let url = 'http://localhost:8080/files/' + filename + '/' + extraVariable;
return axios.get(url, { responseType: 'arraybuffer' }).then((response) => {
return response;
})};
最后一步> 下载
借助js-file-download,您可以触发浏览器将数据保存到文件中,就像下载文件一样。
DownloadFile('filename.extension', 'extraVariable').then(
(response) => {
fileDownload(response.data, filename);
}
, (error) => {
// ERROR
});
答案 4 :(得分:2)
如果您需要从服务器的文件系统下载巨大的文件,则 ByteArrayResource 可以占用所有Java堆空间。在这种情况下,您可以使用FileSystemResource
答案 5 :(得分:1)
@GetMapping("/downloadfile/{productId}/{fileName}")
public ResponseEntity<Resource> downloadFile(@PathVariable(value = "productId") String productId,
@PathVariable String fileName, HttpServletRequest request) {
// Load file as Resource
Resource resource;
String fileBasePath = "C:\\Users\\v_fzhang\\mobileid\\src\\main\\resources\\data\\Filesdown\\" + productId
+ "\\";
Path path = Paths.get(fileBasePath + fileName);
try {
resource = new UrlResource(path.toUri());
} catch (MalformedURLException e) {
e.printStackTrace();
return null;
}
// Try to determine file's content type
String contentType = null;
try {
contentType = request.getServletContext().getMimeType(resource.getFile().getAbsolutePath());
} catch (IOException ex) {
System.out.println("Could not determine file type.");
}
// Fallback to the default content type if type could not be determined
if (contentType == null) {
contentType = "application/octet-stream";
}
return ResponseEntity.ok().contentType(MediaType.parseMediaType(contentType))
.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
.body(resource);
}
要测试它,请使用邮递员
答案 6 :(得分:0)
使用Apache IO可能是复制流的另一种选择
@RequestMapping(path = "/file/{fileId}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<?> downloadFile(@PathVariable(value="fileId") String fileId,HttpServletResponse response) throws Exception {
InputStream yourInputStream = ...
IOUtils.copy(yourInputStream, response.getOutputStream());
response.flushBuffer();
return ResponseEntity.ok().build();
}
maven依赖
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-io</artifactId>
<version>1.3.2</version>
</dependency>