Develop Reference

Android send POST request in Java to ASP.net Web API

When I used HttpUrlConnection to send POST request from Android to ASP.net Web API. It seems not working.
String baseUrl = "http://<IP Address>/Save/Document";
URL url = new URL(baseUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json; charset=utf-8");
DataOutputStream os = new DataOutputStream(conn.getOutputStream());
JSONObject ap = new JSONObject();
// Where data is a JSON string
// Like [{Test: 1}, {Test: 2}]
ap.put("",new Gson().toJson(data));
OutputStreamWriter ap_osw= new OutputStreamWriter(conn.getOutputStream());
ap_osw.write(ap.toString());
ap_osw.flush();
ap_osw.close();
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
StringBuilder response = new StringBuilder();
while ((output = br.readLine()) != null) {
response.append(output);
response.append('\r');
}
String mes = response.toString();
Log.i("INFO", mes);
conn.disconnect();
When executing the above code, it will have an FileNotFoundException in
conn.getInputStream()
I also tried to implement source code in HttpClient style.
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(baseUrl);
try {
StringEntity se = new StringEntity((new Gson()).toJson(data));
httpPost.setEntity(se);
httpPost.setHeader("Accept", "application/json");
httpPost.setHeader("Content-Type", "application/json");
HttpResponse response = httpClient.execute(httpPost);
InputStream inputStream = response.getEntity().getContent();
String result = "";
if (inputStream != null)
result = convertInputStreamToString(inputStream);
else
result = "Did not work!";
Log.i("RESPONSE", result);
} catch (Exception ex) {
Log.i("Exception", ex.getMessage());
}
return output;
And this time, it shows "The requested resource does not support http method 'get'".
I have no ideas how to implement the POST request method to send data from Android to ASP.net Web API. Any recommendations?
Finally, the following coding is my ASP.net Web API for reference.
[HttpPost]
[Route("Save/Document")]
public HttpResponseMessage Post([FromBody]string model)
{
var resp = new HttpResponseMessage(HttpStatusCode.OK);
resp.Content = new StringContent(model, System.Text.Encoding.UTF8, "text/plain");
return resp;
}

Finally, I got a solution to fix this problem. It is due to the POST data in request body can not be read from Web API.
When the request Content-Type is "application/json",
Using string, The request body should be a plain text (e.g. "Text Message").
[FromBody] string inStr
Using self-defined class, The request body should be a json string
(e.g { KEY: VALUE })
[FromBody] YourClass inObj
Using array of self-defined class, The request body should be a json array string (e.g [{ KEY: VALUE }])
[FromBody] YourClass[] inObj
And the self-defined class should be like as following:-
class YourClass {
public string KEY { get; set; }
}
Btw. Thanks for all reply and useful information.

Recieving HTML file as responce instead of JSON Object through get request

I am developing an android app where user logs on to his/her account. After logging in I will receive XSRF token and Laravel Session Id to recognise the specific user. I have to send these tokens for every request I send to the API's to get the appropriate information. But when I am sending the required details as shown in the image, I am getting HTMl file as response instead of getting JSON Object. I was seriously stuck at this problem. Correct Solution may take forward the whole app.
class RegisterConnection extends AsyncTask<String,String,JSONObject> {
protected JSONObject doInBackground(String... arg0) {
JSONObject output = new JSONObject();
DefaultHttpClient client = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(client.getParams(), 5000); //Timeout Limit
HttpResponse response = null;
try {
HttpGet get = new HttpGet(statsURL);
get.setHeader("Accept", "application/json");
CookieStore store = new BasicCookieStore();
BasicClientCookie cookie1 = new BasicClientCookie("XSRF-TOKEN", XSRF);
BasicClientCookie cookie2 = new BasicClientCookie("laravel_session", laravel);
store.addCookie(cookie1);
store.addCookie(cookie2);
client.setCookieStore(store);
response = client.execute(get);
if(response!=null){
InputStream in = response.getEntity().getContent();
String resultstring = Utilities.convertStreamToString(in);
Log.i("Result1", resultstring);
output = new JSONObject(resultstring);
Log.i("Result2", output.toString());
}
} catch(Exception e) {
e.printStackTrace();
try {
output.put("sai","error");
Log.i("MainActivity", output.toString());
} catch (JSONException e1) {
e1.printStackTrace();
}
return output;
}
return output;
}
These are the server requirements
http://imgur.com/OY9Q673
This is the Output received
http://imgur.com/IB5AEcT

As far as I can tell, there is nothing wrong with your Android client code.
You are getting HTML from the server so the main reason could be that your Laravel server is rendering the views and sending you back html instead of JSON. Instead of rendering the views on the server, you should send JSON response on your Laravel server side.

Add Jsoup dependency in your gradle file
implementation 'org.jsoup:jsoup:1.11.2'
Document document = Jsoup.parse("http://imgur.com/IB5AEcT");
Elements el = doc.select("button");
Log.i("..........",""+el.attr("data-invite-details"));
Jsoup tutorial
http://jsoup.org/apidocs/org/jsoup/Jsoup.html

How to make a web request sending a HASH key and get a Response Android

I've searched everywhere on how to make this happen but with no results.
First I need to make a request to a website then send a hash (which I already have) and get a response with some data.
I was able to connect but I'm not able to use the hash key to get the data.
Can anyone help me how to do this using android?
Thanks.
I tried to follow this:Make an HTTP request with android
using a host
The solution:
final HttpClient client = new DefaultHttpClient();
final HttpPost postMethod = new HttpPost(URL);
postMethod.setEntity(new StringEntity(postData, "utf-8"));
String responseData = "";
try {
final HttpResponse response = client.execute(postMethod);
responseData = EntityUtils.toString(response.getEntity(), "utf-8");
} catch(final Exception e) {
// handle exception here
}

This is an example of what you can do:
final String URL = "http://192.168.0.100:8000/myHistory/mobile/?user=";
HttpClient client;
StringBuilder url = new StringBuilder(URL);
url.append(user);
url.append("&pwd=");
url.append(hash);
client = new DefaultHttpClient();
HttpGet get = new HttpGet(url.toString());
HttpResponse response = null;
try {
response = client.execute(get);
} catch (IOException e) {
e.printStackTrace();
}
int status = 0;
status = response.getStatusLine().getStatusCode();
if (status == 200) {
HttpEntity entity = response.getEntity();
String data = "";
try {
data = EntityUtils.toString(entity);
} catch (IOException e) {
e.printStackTrace();
}
//Here you manipulate the 'data' variable, which is in HTML format.

It depends on which kind of hash you are using (SHA-N, MD5, etc) and the kind of framework you are using to build the server. Try to search on the documentation of your framework which kind of cryptographic hash function is used. Then search on internet an API that implements this cryptographic hash function on your code (e.g., Django uses PBKDF2). After that, you need to define the parameters of this function (salt, number of iterations, password (or hash)). The algorithm calculates the hash (password) using the salt and number of iterations values. So when you are trying to access a server you have to send via HTTP the hash that was generated. If this hash is the same hash generated on the server side, then the authentication is successful.

Passing cookie with an HTTT GET

I am trying to get a list of user subreddits via the reddit api. Currently I am able to do a post for login which returns a cookie and modhash. Those are the parameters I'm passing to my method below. However each time I call the function I get an empty response:
"{}"
How can I pass a cookie and modhash via HTTPGET to get a valid response?
public void getUserSubreddits(String[] loginInfo){
HttpClient client = new DefaultHttpClient();
URL url = null;
try {
url = new URL("http://www.reddit.com/subreddits/mine/.json?limit=100");
HttpGet httpGet = new HttpGet(String.valueOf(url));
client.getParams().setParameter(CoreProtocolPNames.USER_AGENT, System.getProperty("http.agent"));
httpGet.addHeader("cookie", loginInfo[1]);
httpGet.addHeader("modhash", loginInfo[0]);
HttpResponse response = client.execute(httpGet);
HttpEntity ht = response.getEntity();
BufferedHttpEntity buf = new BufferedHttpEntity(ht);
InputStream is = buf.getContent();
BufferedReader r = new BufferedReader(new InputStreamReader(is));
StringBuilder total = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
total.append(line);
}
Log.d(TAG,total.toString());
} catch (Exception e) {
e.printStackTrace();
}
}

It was a simple mistake. To anyone in the future trying this I solved the problem by using Chrome to inspect the headers of an active session on http://www.reddit.com/subreddits/mine/.json?limit=100 url and found that the cookie header started with:
reddit_session
So I removed the modhash changed the my header parameter to read:
httpGet.addHeader("cookie", "reddit_session="+loginInfo[1]+";");
With this I got a valid response.

parse Multipart response in Android

I'm sending images and json text from the android client to a tomcat server and the other way around by using Multipart HttpPost's. Sending a Multipart Entity to the server is no big deal, because you can process the parts easily using request.getPart(<name>). But at the client side you can only access the response as a Stream. So I end up appending both, the JSON string and the image to the same ServletOutputStream and have to parse them by hand on the client side. I found apache-mime4j in the web but its hardly documented and I cant find a single example how to use it.
On the server side I build the response like this:
ServletResponse httpResponse = ctx.getResponse();
ResponseFacade rf = (ResponseFacade) httpResponse;
rf.addHeader("Access-Control-Allow-Origin", "*");
rf.addHeader("Access-Control-Allow-Methods", "POST");
rf.addHeader("content-type", "multipart/form-data");
httpResponse.setCharacterEncoding("UTF-8");
MultipartResponse multi = new MultipartResponse((HttpServletResponse) httpResponse);
ServletOutputStream out = httpResponse.getOutputStream();
multi.startResponse("text/plain");
out.println(CMD + "#" + content);
multi.endResponse();
multi.startResponse("image/jpeg");
out.write(data);
multi.endResponse();
multi.finish();
ctx.complete();
And on the client side on Android I want to access the text and the image data:
InputStream is = response.getEntity().getContent();
MimeStreamParser parser = new MimeStreamParser();
MultipartContentHandler con = new MultipartContentHandler();
parser.setContentHandler(con);
try {
parser.parse(is);
String json = con.getJSON(); //get extracted json string
byte[] imgBytes = con.getBytes(); //get extracted bytes
} catch (MimeException e) {
e.printStackTrace();
} finally {
is.close();
}
class MultipartContentHandler implements ContentHandler{
public void body(BodyDescriptor bd, InputStream in) throws MimeException, IOException {
//if MIME-Type is "text/plain"
// process json-part
//else
// process image-part
}
In the method body(BodyDescriptor bd, InputStream in) my whole response is treated as text\plain mime type. So I finally have to parse every byte manually again and the whole apache-mime4j is useless. Can you tell me what I am doing wrong? Thanks!

Ok i finally solved it myself. No here's what i did:
First I need to create a multipart/mixed Response at the server side. It can be done using apache-mime-4j API:
ServletResponse httpResponse = ctx.getResponse();
ResponseFacade rf = (ResponseFacade) httpResponse;
httpResponse.setCharacterEncoding("UTF-8");
httpResponse.setContentType("multipart/mixed");
MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE, "SEPERATOR_STRING",Charset.forName("UTF-8"));
entity.addPart("json", new StringBody(CMD + "#" + content, "text/plain", Charset.forName("UTF-8")));
entity.addPart("image", new ByteArrayBody(data, "image/jpeg", "file"));
httpResponse.setContentLength((int) entity.getContentLength());
entity.writeTo(httpResponse.getOutputStream());
ctx.complete();
Now at the client side to access the MIME-Parts of the HttpResponse I use the javax.mail API.
ByteArrayDataSource ds = new ByteArrayDataSource(response.getEntity().getContent(), "multipart/mixed");
MimeMultipart multipart = new MimeMultipart(ds);
BodyPart jsonPart = multipart.getBodyPart(0);
BodyPart imagePart = multipart.getBodyPart(1);
But you can't use the native API, instead take this one http://code.google.com/p/javamail-android/
Now you can proceed handling your individual parts.

It is also possible with apache-mime-4j:
HttpURLConnection conn = ...;
final InputStream is = conn.getInputStream();
try {
final StringBuilder sb = new StringBuilder();
sb.append("MIME-Version: ").append(conn.getHeaderField("MIME-Version")).append("\r\n");
sb.append("Content-Type: ").append(conn.getHeaderField("Content-Type")).append("\r\n");
sb.append("\r\n");
parser.parse(new SequenceInputStream(new ByteArrayInputStream(sb.toString().getBytes("US-ASCII")), is));
} catch (final MimeException e) {
e.printStackTrace();
} finally {
is.close();
}