Sending UTF-8 string using HttpURLConnection

Question

till now I've used the following code snippet in order to send and recieve JSON strings:

static private String sendJson(String json,String url){
    HttpClient httpClient = new DefaultHttpClient();
    String responseString = "";
    try {
        HttpPost request = new HttpPost(url);
        StringEntity params =new StringEntity(json, "UTF-8");
        request.addHeader("content-type", "application/json");
        request.setEntity(params);
        HttpResponse response = httpClient.execute(request);
        HttpEntity entity = response.getEntity();
        responseString = EntityUtils.toString(entity, "UTF-8");

    }catch (Exception ex) {
        ex.printStackTrace();
        // handle exception here
    } finally {
        httpClient.getConnectionManager().shutdown();
    }
    return responseString;
}

The code above worked perfect even if the json string contained UTF-8 chars, and everything worked fine.

For several reasons I had to change the way I send HTTP post requests and use HttpURLConnection instead apache's HttpClient. Here's my code:

static private String sendJson(String json,String url){
    String responseString = "";
    try {
        URL m_url = new URL(url);
        HttpURLConnection conn = (HttpURLConnection)m_url.openConnection();
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("content-type", "application/json");
        DataOutputStream outputStream = new DataOutputStream(conn.getOutputStream());
        outputStream.writeBytes(json);
        outputStream.flush();
        outputStream.close();

        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        StringBuilder sb = new StringBuilder();
        String line;
        while ((line = br.readLine()) != null) {
            sb.append(line+"\n");
        }
        br.close();
        responseString = sb.toString();
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return responseString;
}

This code works well for normal English characters, but doesn't seem to support UTF-8 characters in the json string, since it fails each time. (when sending json to server, server crushes saying that utf8 cant decode a certain byte, but when recieving utf8 json from server I think it does work since I manage to view the special characters).

Server didn't change at all and worked fine with previous code, so the problem is 100% on this new code snippet.

Any idea how to fix the json string sending so it would support UTF 8? Thanks

Answer 1

I think the problem is in this part:

DataOutputStream outputStream = new DataOutputStream(conn.getOutputStream());
outputStream.writeBytes(json);
outputStream.flush();
outputStream.close();

Instead of doing this you need to encode json as UTF-8
and send those bytes which represent the UTF-8 encoding.

Try using this:

Charset.forName("UTF-8").encode(json)

See:

Charset.encode

An even simpler approach is to use e.g. a BufferedWriter wrapping an
OutputStreamWriter. The OutputStreamWriter knows about its own encoding
and so it will do the work for you (the encoding work of the json String).

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(), "UTF-8"));
bw.write(json);
bw.flush();
bw.close();