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.

Android HttpURLConnection sending data in post request doesnt work, but javascript XMLHttpRequest does

I have a server using mongodb, mongoose and node.js.
I have implemented some GET and POST methods.
Inside a HTML website, I can post data to the server within an XMLHttpRequest as follows inside javascript:
function postPlantType(base64){
var httpPost = new XMLHttpRequest(),
path = "http://...", // real URL taken out here
header = ('Content-Type','application/json'),
data = JSON.stringify({image:base64});
httpPost.onreadystatechange = function(err) {
if (httpPost.readyState == 4 && httpPost.status == 201){
console.log(httpPost.responseText);
} else {
console.log(err);
}
};
path = "http://..." // real URL taken out here
httpPost.open("POST", path, true);
httpPost.send(data);
}
this works fine. Now I want to create an Android app, making use of such a POST request, but my Code is not working successfully. Here is my Code:
private class PostNewPlantTask extends AsyncTask<String, Integer, String> {
String responseString = "";
int response;
InputStream is = null;
protected String doInBackground(String... urls){
DataOutputStream wr=null;
try {
URL url = new URL(urls[0]); // urls[0] is the url of the http request "http://www..."
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("POST");
conn.setDoOutput(true);
conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
String json = "{\"image\":\"data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAMCAgICAgMCAgIDAwMDBAYE...\"}";
Log.d("json", json.toString());
conn.setRequestProperty("Content-length", json.getBytes().length + "");
conn.setDoInput(true);
conn.setUseCaches(false);
conn.setAllowUserInteraction(false);
OutputStream os = conn.getOutputStream();
os.write( json.getBytes("UTF-8"));
os.close();
// Starts the query
conn.connect();
response = conn.getResponseCode();
if (response >= 200 && response <=399){
is = conn.getInputStream();
} else {
is = conn.getErrorStream();
}
// Convert the InputStream into a string
String contentAsString = readIt(is, 200);
responseString = contentAsString;
conn.disconnect();
} catch (Exception e) {
responseString = "error occured: "+e;
} finally {
if (is != null){
try { is.close();} catch (Exception e) {Log.d("HTTP POST planttypes","Exception occured at closing InputStream: "+e);}
}
}
Log.d("HTTP POST plants", "The response is: " + response + responseString);
return responseString;
}
protected void onPostExecute(String result){
// TODO: nothing(?)
// give user feedback(?)
}
}
NOTE: If I change the json String to invalid json content e.g. deleting the last "}", The response of the server is
400 "code":"InvalidContent","message":"Invalid JSON: Unexpected end of input"
So I assume the entire json string must be correct, if its unchanged.
I am hardcoding the base64encoded image String here instead of encode a real image, because of testing issues. You can see the image at this jsfiddle.
If I see it correctly, its the exact same request as done from my javascript, but I get 500 internal server error.
However, in order to get more information, here is the server function, that is called for that request url:
function postNewPlantType(req, res, next){
var json = JSON.parse(req.body);
newPlantTypeData = {
image:json.image
};
var imageBuffer = decodeBase64Image(json.image);
newPlantType = new Planttype(newPlantTypeData);
newPlantType.save(function(err){
if (err) return next(new restify.InvalidArgumentError(JSON.stringify(err.errors)));
var fileName = cfg.imageFolder + "" + newPlantType._id + '.jpeg';
fs.writeFile(fileName, imageBuffer.data, function(error){
if (error) log.debug(error);
log.debug("PlantType-ImageFile successfully created on server.");
});
res.send(201, newPlantType);
log.debug("PlantType successfully saved in database.");
});
}
What I am wondering about is, the javascript request is working, but the android request is not. So I assume there must be a mistake in my android code. Can you help me and explain, what the error is and what I have to change?

You probably need to encode it properly:
conn.connect();
DataOutputStream printout = new DataOutputStream(conn.getOutputStream ());
printout.write(URLEncoder.encode(json.toString(),"UTF-8"));
printout.flush ();
printout.close ();
response = conn.getResponseCode();
...

After lots of days of investigation I finally got a 201 response by changing the line
conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
to
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");
Well.. I was sending an encoded JSON and not a json itself...

Sending HTTP DELETE request in Android

My client's API specifies that to remove an object, a DELETE request must be sent, containing Json header data describing the content. Effectively it's the same call as adding an object, which is done via POST. This works fine, the guts of my code is below:
HttpURLConnection con = (HttpURLConnection)myurl.openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);
con.setUseCaches(false);
con.connect();
OutputStreamWriter wr = new OutputStreamWriter(con.getOutputStream());
wr.write(data); // data is the post data to send
wr.flush();
To send the delete request, I changed the request method to "DELETE" accordingly. However I get the following error:
java.net.ProtocolException: DELETE does not support writing
So, my question is, how do I send a DELETE request containing header data from Android? Am I missing the point - are you able to add header data to a DELETE request? Thanks.

The problematic line is con.setDoOutput(true);. Removing that will fix the error.
You can add request headers to a DELETE, using addRequestProperty or setRequestProperty, but you cannot add a request body.

This is a limitation of HttpURLConnection, on old Android versions (<=4.4).
While you could alternatively use HttpClient, I don't recommend it as it's an old library with several issues that was removed from Android 6.
I would recommend using a new recent library like OkHttp:
OkHttpClient client = new OkHttpClient();
Request.Builder builder = new Request.Builder()
.url(getYourURL())
.delete(RequestBody.create(
MediaType.parse("application/json; charset=utf-8"), getYourJSONBody()));
Request request = builder.build();
try {
Response response = client.newCall(request).execute();
String string = response.body().string();
// TODO use your response
} catch (IOException e) {
e.printStackTrace();
}

getOutputStream() only works on requests that have a body, like POST. Using it on requests that don't have a body, like DELETE, will throw a ProtocolException. Instead, you should add your headers with addHeader() instead of calling getOutputStream().

I know is a bit late, but if anyone falls here searching on google like me I solved this way:
conn.setRequestProperty("X-HTTP-Method-Override", "DELETE");
conn.setRequestMethod("POST");

DELETE request is an extended form of GET request, as per the android documentation you cannot write in the body of DELETE request.
HttpUrlConnection will throw "unable to write protocol exception".
If you still want to write the parameter in the body, i suggest you to use the OKHttp Library.
OKHttp documentation
If you are intrested to use more simpler library then you can try
SimpleHttpAndroid library
One thing to remember here is if you are not writing anything in the body then remove the line
conn.setDoOutput(true);
Thanks, Hopefully it may help.

Try below method for call HttpDelete method, it works for me, hoping that work for you as well
String callHttpDelete(String url){
try {
HttpParams httpParams = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParams, 15000);
HttpConnectionParams.setSoTimeout(httpParams, 15000);
//HttpClient httpClient = getNewHttpClient();
HttpClient httpClient = new DefaultHttpClient();// httpParams);
HttpResponse response = null;
HttpDelete httpDelete = new HttpDelete(url);
response = httpClient.execute(httpDelete);
String sResponse;
StringBuilder s = new StringBuilder();
while ((sResponse = reader.readLine()) != null) {
s = s.append(sResponse);
}
Log.v(tag, "Yo! Response recvd ["+s.toString()+"]");
return s.toString();
} catch (Exception e){
e.printStackTrace();
}
return s.toString();
}

You can't just use the addHeader() method?

Here is my Delete request method.
Simply it is post request with extra RequestProperty
connection.setRequestProperty("X-HTTP-Method-Override", "DELETE");
Below the complete method.
public void executeDeleteRequest(String stringUrl, JSONObject jsonObject, String reqContentType, String resContentType, int timeout) throws Exception {
URL url = new URL(stringUrl);
HttpURLConnection connection = null;
String urlParameters = jsonObject.toString();
try {
connection = (HttpURLConnection) url.openConnection();
//Setting the request properties and header
connection.setRequestProperty("X-HTTP-Method-Override", "DELETE");
connection.setRequestMethod("POST");
connection.setRequestProperty("User-Agent", USER_AGENT);
connection.setRequestProperty(CONTENT_TYPE_KEY, reqContentType);
connection.setRequestProperty(ACCEPT_KEY, resContentType);
connection.setReadTimeout(timeout);
connection.setConnectTimeout(defaultTimeOut);
connection.setUseCaches(false);
connection.setDoInput(true);
connection.setDoOutput(true);
// Send request
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
responseCode = connection.getResponseCode();
// To handle web services which server responds with response code
// only
try {
response = convertStreamToString(connection.getInputStream());
} catch (Exception e) {
Log.e(Log.TAG_REST_CLIENT, "Cannot convert the input stream to string for the url= " + stringUrl + ", Code response=" + responseCode + "for the JsonObject: " + jsonObject.toString(), context);
}
} catch (
Exception e
)
{
if (!BController.isInternetAvailable(context)) {
IntentSender.getInstance().sendIntent(context, Constants.BC_NO_INTERNET_CONNECTION);
Log.e(Log.TAG_REST_CLIENT, "No internet connection", context);
}
Log.e(Log.TAG_REST_CLIENT, "Cannot perform the POST request successfully for the following URL: " + stringUrl + ", Code response=" + responseCode + "for the JsonObject: " + jsonObject.toString(), context);
throw e;
} finally{
if (connection != null) {
connection.disconnect();
}
}
}
I hope it helped.

To add closure to this question, it transpired that there is no supported method to send an HTTP DELETE request containing header data.
The solution was for the client to alter their API to accept a standard GET request which indicated that the action should be a delete, containing the id of the item to be deleted.
http://clienturl.net/api/delete/id12345

POST with Basic Auth fails on Android but works in C#

I have an app I am developing that requires me to post data to a 3rd party API. I have been struggling with authentication since the beginning and kept putting off further and further, and now I'm stuck.
I have tried using an Authenticator, but have read all about how there appears to be a bug in certain Android versions: Authentication Example
I have tried several different options, including the Apache Commons HTTP Library with no success. After all of this, I decided to make sure that the API wasn't the pain point. So I wrote a quick WinForms program to test the API, which worked perfectly on the first try. So, the idea that I'm working from and the API I working with both seem fine, but I am in desperate need of some guidance as to why the Java code isn't working.
Examples follow:
C# Code that works everytime:
System.Net.ServicePointManager.Expect100Continue = false;
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create(addWorkoutUrl);
// Set the Method property of the request to POST.
request.Method = "POST";
// Create POST data and convert it to a byte array.
string postData = "distance=4000&hours=0&minutes=20&seconds=0&tenths=0&month=08&day=01&year=2011&typeOfWorkout=standard&weightClass=H&age=28";
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Set the ContentType property of the WebRequest.
request.Headers["X-API-KEY"] = apiKey;
request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes("username:password"));
request.ContentType = "application/x-www-form-urlencoded";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
// Get the response.
WebResponse response = request.GetResponse();
// Display the status.
MessageBox.Show(((HttpWebResponse)response).StatusDescription);
// Get the stream containing content returned by the server.
dataStream = response.GetResponseStream();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader(dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd();
// Display the content.
MessageBox.Show(responseFromServer);
// Clean up the streams.
reader.Close();
dataStream.Close();
response.Close();
Java code for Android that currently returns a 500:Internal Server Error, though I believe this is my fault.
URL url;
String data = "distance=4000&hours=0&minutes=20&seconds=0&tenths=0&month=08&day=01&year=2011&typeOfWorkout=standard&weightClass=H&age=28";
HttpURLConnection connection = null;
//Create connection
url = new URL(urlBasePath);
connection = (HttpURLConnection)url.openConnection();
connection.setConnectTimeout(10000);
connection.setUseCaches(false);
connection.setRequestProperty("User-Agent","Mozilla/5.0 ( compatible ) ");
connection.setRequestProperty("Accept","*/*");
connection.setRequestProperty("X-API-KEY", apiKey);
connection.setRequestProperty("Authorization", "Basic " +
Base64.encode((username + ":" + password).getBytes("UTF-8"), Base64.DEFAULT));
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", "" + Integer.toString(data.getBytes("UTF-8").length));
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.write(data.getBytes("UTF-8"));
wr.flush();
wr.close();
statusCode = connection.getResponseCode();
statusReason = connection.getResponseMessage();
//At this point, I have the 500 error...

I figured out the problem, and the solution finally after stumbling across the root cause as mentioned in the comment above.
I was using Base64.encode() in my example, but I needed to be using Base64.encodeToString().
The difference being that encode() returns a byte[] and encodeToString() returns the string I was expecting.
Hopefully this will help somebody else who is caught by this.

Here's a nicer method to do to the POST.
install-package HttpClient
Then:
public void DoPost()
{
var httpClient = new HttpClient();
var creds = string.Format("{0}:{1}", _username, _password);
var basicAuth = string.Format("Basic {0}", Convert.ToBase64String(Encoding.UTF8.GetBytes(creds)));
httpClient.DefaultRequestHeaders.Add("Authorization", basicAuth);
var post = httpClient.PostAsync(_url,
new FormUrlEncodedContent(new Dictionary<string, string>
{
{ "name", "Henrik" },
{ "age", "99" }
}));
post.Wait();
}

I have tried this in java
import java.io.*;
import java.net.*;
class download{
public static void main(String args[]){
try{
String details = "API-Key=e6d871be90a689&orderInfo={\"booking\":{\"restaurantinfo\":{\"id\":\"5722\"},\"referrer\":{\"id\": \"9448476530\" }, \"bookingdetails\":{\"instructions\":\"Make the stuff spicy\",\"bookingtime\": \"2011-11-09 12:12 pm\", \"num_guests\": \"5\"}, \"customerinfo\":{\"name\":\"Ramjee Ganti\", \"mobile\":\"9345245530\", \"email\": \"sajid#pappilon.in\", \"landline\":{ \"number\":\"0908998393\",\"ext\":\"456\"}}}}";
Authenticator.setDefault(new Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication("admin", "1234".toCharArray());
}
});
HttpURLConnection conn = null;
//URL url = new URL("http://api-justeat.in/ma/orders/index");
URL url = new URL("http://api.geanly.in/ma/order_ma/index");
conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
conn.setDoInput (true);
conn.setRequestMethod("POST");
//conn.setRequestMethod(HttpConnection.POST);
DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());
outStream.writeBytes(details);
outStream.flush();
outStream.close();
//Get Response
InputStream is = conn.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while((line = rd.readLine()) != null) {
System.out.println(line);
}
rd.close();
System.out.println(conn.getResponseCode() + "\n\n");
}catch(Exception e){
System.out.println(e);
}
}
}
this could help.

Connecting to a webserver with android

I have to connect to a webserver from android and I have to access a webservice and a webpage from the webserver. Can anybody help me? Please give step by step process with some code snippets because I am new to android and I don't know anything in connecting to a webserver.

You can use an HttpClient:
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(uri);
HttpResponse httpResponse = httpClient.execute(httpGet);
BufferedReader reader = new BufferedReader(
new InputStreamReader(httpResponse.getEntity().getContent()));
// user reader to read & parse response
reader.close();
Parsing the response obviously depends on the format (e.g. SOAP, JSON, etc.)

You haven't given very much info (what kind of web page, XML/JSON/HTML/etc. ?). But the basic principles of regular Java apply. Using URL and InputStream:
URL url = new URL(...);
InputStream is = url.openStream();
And from there it depends what kind of data you're dealing with.

If you don't want to use an additional library, here is a means for sending an "id" and "name" to a server:
URL url = null;
try {
String registrationUrl = String.format("http://myserver/register?id=%s&name=%s", myId, URLEncoder.encode(myName,"UTF-8"));
url = new URL(registrationUrl);
URLConnection connection = url.openConnection();
HttpURLConnection httpConnection = (HttpURLConnection) connection;
int responseCode = httpConnection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
Log.d("MyApp", "Registration success");
} else {
Log.w("MyApp", "Registration failed for: " + registrationUrl);
}
} catch (Exception ex) {
ex.printStackTrace();
}
You could just as easily send other data via this URI "GET" style, but if you need to send something more detailed a POST will be required.
Note: Originally posted to answer a similar question here: How to connect android to server