Upload image with Java MultipartEntity to Node.js server using express and multer

Question

I'm trying to upload an image from an Android application using a custom MultipartEntity which also updates a ProgressDialog (that also being my reason for using the deprecated MultipartEntity).
Relevant Java code:

        File file = new File(imgPath);

        HttpPost post = new HttpPost("http://" + SERVER + "/upload");

        MultipartEntity entity = new MyMultipartEntity(new MyMultipartEntity.ProgressListener()
        {
            public void transferred(long num)
            {
                publishProgress((int) ((num / (float) totalSize) * 100));
                Log.d("DEBUG", num + " - " + totalSize);
            }
        });
        ContentBody cbFile = new FileBody(file, "image/jpeg");
        entity.addPart("source", cbFile);

        totalSize = entity.getContentLength();

        post.setEntity(entity);

        HttpResponse response = client.execute(post);
        int statusCode = response.getStatusLine().getStatusCode();

        if(statusCode == HttpStatus.SC_OK){
            String fullRes = EntityUtils.toString(response.getEntity());
            Log.d("DEBUG", fullRes);

        } else {
            Log.d("DEBUG", "HTTP Fail, Response Code: " + statusCode);
        }

Node.js server file:

var fs = require('fs');

var express = require('express');
var app = express();

var multer = require('multer');
var upload = multer(
    { 
        limits: {
            fieldNameSize: 999999999,
            fieldSize: 999999999
        },
        dest: 'uploads/' }
    );

app.get('/', function(req, res){
    res.send(
        '<form action="/upload" method="post" enctype="multipart/form-data">'+
        '<input type="file" name="source">'+
        '<input type="submit" value="Upload">'+
        '</form>'
    );
});

app.post('/upload', upload.any(), function(req, res){

    console.log(req.files);

    var tmp_path = req.files[0].path;

    var target_path = 'uploads/' + req.files[0].originalname;

    var src = fs.createReadStream(tmp_path);
    var dest = fs.createWriteStream(target_path);
    src.pipe(dest);
    src.on('end', function() { res.send("ok"); });
    src.on('error', function(err) { res.send({error: "upload failed"}); });
});

app.get('/info', function(req, res){
    console.log(__dirname);
    res.send("image upload server: post /upload");
});

app.listen(8080);
console.log('started server on localhost...');

I've also tried using the upload.single() approach (which works through the form) but that requires the name of the field which I'm not sure how/if I can add to the Java multipart entity object.

What I'm currently getting is an empty files array on the request and a source variable on the request body containing what seems like the raw data of the image, so basically it looks like multer isn't doing anything at all. What am I missing?

Thank you!

Thanks, @Vlad . Everything is working! I just have one question: when testing this on localhost, the server saves 2 files with the same size; how can I remove the temp file, only leaving the final file? — Minoru
– Minoru, Commented May 29, 2017 at 14:03

Vlad Vidac · Accepted Answer · 2016-06-07 08:35:53Z

5

I ended up using the Android Ion library - https://github.com/koush/ion

Java code:

Ion.with(context)
            .load("http://" + SERVER + ":8080/upload")
            .progressDialog(pd)
            .setMultipartParameter("name", "source")
            .setMultipartFile("image", "image/jpeg", new File(imgPath))
            .asJsonObject()
            .setCallback(new FutureCallback<JsonObject>() {
                @Override
                public void onCompleted(Exception e, JsonObject result) {

                    //do stuff with result
                }
            });

The server code remained unchanged.

answered Jun 7, 2016 at 8:35

Vlad Vidac

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4 Comments

Rick Over a year ago

Thanks for this. Got this after hours and hours of searching. Honestly, nothing else was working.

VishAl Over a year ago

hello I tried using this but I am not getting req.files[0].path in the req.files object on the server can you help me out with this?

Rusty Over a year ago

@Vlad Is there a way to send multiple files in single request?

andrea.rinaldi Over a year ago

Number one. Saved my day.

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