使用带有角的ResponseEntity下载任何文件不起作用

我需要在客户端使用angular下载文件，该文件可以具有pdf或excel或image或txt的任何格式…我的方法仅适用于txt文件，但给我excel和image的失败格式，对于pdf，它会给出一个空的pdf。

所以在我的控制器中，这里是调用service方法的函数：

    vm.downloadFile = downloadFile;

    function downloadFile(file){
        var urlDir = "C://STCI//"+idpeticion;
        return VerDocServices.downloadFile(file,urlDir)
          .then(function(response) {
            var data = response.data;
            var filename = file;
            var contentType = 'application/octet-stream';//octet-stream             
            var linkElement = document.createElement('a');
            try {
                var blob = new Blob([ data ], {
                    type : contentType
                });
                var url = window.URL.createObjectURL(blob);
                linkElement.setAttribute('href', url);
                linkElement.setAttribute("download", filename);
                var clickEvent = new MouseEvent("click", {
                    "view" : window,
                    "bubbles" : true,
                    "cancelable" : false
                });
                linkElement.dispatchEvent(clickEvent);
            } catch (ex) {
                console.log(ex);
                throw ex;
            }
        }).catch(function(response) {
            alert('Se ha producido un error al exportar del documento');
            console.log(response.status);
            throw response;
        });
    }

而我的service.js具有：

angular.module('mecenzApp').service('VerDocServices',['$http',function($http) {

this.downloadFile = function(file,urlDir) {

    return $http.get('api/downloadFile', {
        params : {
            file : file,
            urlDir : urlDir
        }
    }); }} ]);

我的服务方法是这样的：

@GetMapping("/downloadFile")
@Timed
public ResponseEntity<byte[]> downloadFile(@RequestParam(value = "file") String file, @RequestParam(value = "urlDir") String urlDir) {
    log.debug("GET ---------------- DOWNLOAD FILE : {}", file);
    log.debug("GET ---------------- From the DIRECTORY: {}",urlDir);

    InputStream fileStream;
    String filepath = urlDir+File.separator+file;
    try {
        File f = new File(filepath);
        log.debug("GET ---------------- FILE: {}",f.getPath());
        fileStream = new FileInputStream(f);
        byte[] contents = IOUtils.toByteArray(fileStream);
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/octet-stream"));   
        String filename = file;
        headers.setContentDispositionFormData(filename, filename);
        ResponseEntity<byte[]> response2 = new ResponseEntity<byte[]>(contents, headers, HttpStatus.OK);
        fileStream.close();
        return response2;

    } catch (FileNotFoundException e) {
       System.err.println(e);
    } catch (IOException e) {
        System.err.println(e);
    }
   return null;
}

你能看看我告诉我我错过了什么吗？

谢谢你:)