How to download a file using a Java REST service ?

Related Question:
     How to zip a folder?
     AngularJs / JavaScript to download a file using web service.


Solution:

 @GET
    @Path("/report/download/file/{filename : .+}")
    @Produces(MediaType.APPLICATION_OCTET_STREAM)
    public Response downloadFilebyPath(@PathParam("filename")  String fileName) {


        System.out.println("file location:--- //"+fileName);
        return download("//"+fileName);
    }

    private Response download(String fileName) {
        Response response = null;
        NumberFormat myFormat = NumberFormat.getInstance();
     myFormat.setGroupingUsed(true);
       // FileOutputStream fos = null;
       // ZipOutputStream zos = null;
        //String zipFile = folderPath + fileName + ".zip";
        //fileListForFiltering = new ArrayList<String>();
        /*String destFolderString = new File(filePath).getName();
        String pattern = "_[0-9]+_[0-9]+";
        Pattern p = Pattern.compile("_[0-9]+_[0-9]+");
        //byte[] buffer = new byte[1024];
        // Zip Utility


/*        File[] files= file.listFiles();
        for (File filename : files){
            if(filename.toString().contains(businessDate)){
                Matcher mm = p.matcher(filename.toString());
                if (!mm.find()) {
                    this.fileListForFiltering.add(filename.getName());
                }
            }
        }*/
       // File zipfile= zipIt(zipFile, filePath, destFolderString);
        //  File zipfile = new File(zipFile) ;
        File file = new File(fileName);
        if (file.exists()) // if (zipfile.exists())
{
            ResponseBuilder builder = Response.ok(file);
            builder.header("Content-Disposition", "attachment; filename=" + file.getName());
            response = builder.build();
            long file_size = file.length();
            LOG.info(String.format("Inside downloadFile==> fileName: %s, fileSize: %s bytes",
                    file, myFormat.format(file_size)));
        } else {
            LOG.error(String.format("Inside downloadFile==> FILE NOT FOUND: fileName: %s",
                    file));

            response = Response.status(404).
                    entity("FILE NOT FOUND: " + file).
                    type("text/plain").
                    build();
        }

        return response;

    }


AngularJs  or javascript