JAX-RS file downloads, multiple content types

Question

Let me provide some context first. I am working on a system that integrates with Microsoft SharePoint 2010, well not really SharePoint as a system but the virtual representation of it's filesystem, document libraries, etc... Users upload files to SharePoint, and my system monitors these files and indexes them into a search engine (including file content). User can interact with this system by means of REST interfaces.

I have created a REST interface to fetch a file for the user corresponding a certain entry in my search engine. This uses the absolute network path as its identifier. An example would be //corporateserver//library1/filex.docx. Due to the same origin policy however I can not load this file client side. Therefore I am trying to transmit it via the server.

I had some success using JAX-RS to transmit data, however, I am getting stuck at the following:

The file the user wishes to download can be of mutliple content types, most of them will be microsoft office formats. I had a look through the list of registered MIME types and came across application/msword or application/vnd.ms-powerpoint

My question: is there a content type that would include Microsoft Office files? If not, how could one proceed to match the correct content types with a file that is being requested. What would happen if one would server a word file with content type text/plain?

Any help on the subject would be greatly appreciated.

EDIT

The code I use to transmit data:

package com.fujitsu.consensus.rest;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.StreamingOutput;

import org.apache.commons.io.IOUtils;
import org.codehaus.jettison.json.JSONException;

@Path("/fetcher")
public class FetcherService {

    @GET
    @Path("/fetch")
    @Produces(MediaType.APPLICATION_OCTET_STREAM)
    public Response fetchFile(@QueryParam("path") String path) 
        throws JSONException, IOException {

        final File file = new File(path);
        System.out.println(path);

        StreamingOutput stream = new StreamingOutput() {
            @Override
            public void write(OutputStream output) throws IOException {
                try {
                    output.write(IOUtils.toByteArray(new FileInputStream(file)));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };

        return Response.ok(stream, MediaType.APPLICATION_OCTET_STREAM)
            .header("Content-Disposition", "inline; filename=\"" + file.getName() + "\"") 
            .build();
    }
}

JavaScript code:

 $.ajax({
   url: "../rest/fetcher/fetch",
   type: "GET", //send it through get method
   data:{path:obj.id},
   success: function(response) {
   console.log(response);},
   error: function(xhr) {//Do Something to handle error}
 });

The response I get on client side:

EDIT 2

I've added a HTTP trace as proof that the headers and data are in fact being transmitted, the download dialogue however is not shown.

The Content-Disposition header does not appear to be working with either inline or attachment.

Thank you for your reply, I did try that. But I only seems to be getting encoded data back. How could I prompt the user to download this file ? — Mark Stroeven, Nov 05 '15 at 10:56
You need the `Content-Disposition` header. See my answer below. — cassiomolin, Nov 05 '15 at 10:57

score 15 · Accepted Answer · edited May 23 '17 at 12:15

15

You could use application/octet-stream as content type and do the following to download files:

@GET
@Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response downloadFile(String fileName) {
    File file = ... // Find your file
    return Response.ok(file, MediaType.APPLICATION_OCTET_STREAM)
        .header("Content-Disposition", "attachment; filename=\"" + file.getName() + "\"")
        .build();
}

Since you are using JavaScript to download files, have a look here and here.

edited May 23 '17 at 12:15

Community

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answered Nov 05 '15 at 10:56

cassiomolin

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added some more info, came a bit further but still not working as intended with the code example provided. – Mark Stroeven Nov 05 '15 at 11:14
@MarkStroeven The response seems fine, since you are downloading a file. The problem might be in the JavaScript you are using. For test purposes, try using `GET` instead of `POST`, send the file name as a query or path parameter and type the URL in the browser instead of using JavaScript. – cassiomolin Nov 05 '15 at 11:21
@MarkStroeven Have a look at my updated answer about downloading files with JavaScript. – cassiomolin Nov 05 '15 at 11:32
Tried both of the threads you linked :) both are giving the error "Not allowed to load local resource" both server and client are actually on the same corporate domain. – Mark Stroeven Nov 05 '15 at 11:41
@MarkStroeven Can you download the file using `GET` and typing the URL in the browser address bar? – cassiomolin Nov 05 '15 at 11:44
Tested it using the file location as a parameter with a get request. I fetches the data, if I print it you see the encoded data again. Its not prompting a download screen. Same thing when I enter it manually. – Mark Stroeven Nov 05 '15 at 12:41

score 1 · Answer 2 · answered Nov 05 '15 at 14:29

Fixed it, used the content-type: application/octet-stream. I also added the header mentioned above:

 return Response.ok(file, MediaType.APPLICATION_OCTET_STREAM)
        .header("Content-Disposition", "attachment; filename=\"" + file.getName() + "\"")
        .build();

my error was thinking that after an ajax call the file would download in the same window. changed my client side code to do the request in another window using :

window.open(resturl);

the reaction was that the browser would open a new window, download the file into the download tray and return to the webpage in which you clicked download whilst closing the download tab. (in about 0.2 seconds).

JAX-RS file downloads, multiple content types

2 Answers2

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