通过Spring REST API用Angular 2下载的文件大小是原来的两倍。 为什么？

Question

I want to download files from angular 2. My problem is, that all files I get from the Spring REST API are twice file size.

Angular Snippet:

return this.authHttp.get(this.restAPI + '/downloadFile/' + fileId)
         .toPromise()
             .then(response => {
                //  var arrayBufferView = new Uint8Array( response.arrayBuffer() );
                //  var blob = new Blob( [ arrayBufferView ], { type: response.headers.get("Content-Type") } );
                //  return blob;

                 return new Blob([response.arrayBuffer()], { type: response.headers.get("Content-Type")})
                })

            .catch(this.handleError);

Spring REST Snippet:

@RequestMapping(value = "/downloadFile2/{fileId}",
        method = RequestMethod.GET)
public void downloadFileHandler2(@RequestHeader("Authorization") String token, 
        @PathVariable String fileId, HttpServletResponse response) throws IOException {

    changeToCustomerDataBase(token);

    File file = projectService.readFromDB(fileId);

    response.addHeader("Content-Disposition", "attachment; filename="+file.getName());
    response.setContentType(Files.probeContentType(file.toPath()));
    response.setContentLengthLong(file.length());

    FileInputStream fis = new FileInputStream(file);
    int c; 
    while((c = fis.read()) > -1) {
        response.getOutputStream().write(c);    
    }

    response.flushBuffer();

    fis.close();
}

Files, thar coming from the database, have the original size.

What is wrong? Did I forget something? I'm very grateful for any help.

Answer 1

I had the same Problem yesterday and solved it. I hope you or anyone else can use the solution. Add responseType: ResponseContentType.Blob to your requestOptions of the authHttp.get you use.

let requestOptions: RequestOptionsArgs = {
        ...,
        responseType: ResponseContentType.Blob
};
.
.
.
return this.http.request(path, requestOptions);

Then use response.blob() instead of new Blob([response.arrayBuffer()], { type: response.headers.get("Content-Type")})

For me that worked. I hope it helps you too.