Develop Reference

HTTP response not giving output

I am working on an application that interacts with a room security control device.
I want to get devices information from API. I am using HttpUrlConnection and POST method. It hits the API and I get 200 OK response but I get the out
"{"json":{"control":{"cmd":"getdevice","uid":256}}} doesn't exist"
I have tried all the solutions from stackoverflow and other platforms but it's not giving the output.
Moreover I have tested this API on Postman and it's working there and giving the device information.
Here is the code:
public class HTTPRequestTask extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
String username = "admin";
String password = "888888";
URL url = null;
try {
url = new URL("http://192.168.100.25/network.cgi");
} catch (MalformedURLException e) {
e.printStackTrace();
}
assert url != null;
HttpURLConnection httpRequest = null;
try {
httpRequest = (HttpURLConnection) url.openConnection();
httpRequest.setRequestMethod("POST");
httpRequest.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
httpRequest.setDoInput(true);
httpRequest.setDoOutput(true);
android.util.Base64.encode(authString.getBytes(), android.util.Base64.DEFAULT);
httpRequest.addRequestProperty("Authorization", "Basic " + "YWRtaW46ODg4ODg4"); // This is auth bytecode
httpRequest.connect();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
JSONObject json = new JSONObject();
JSONObject jsonObject = new JSONObject();
JSONObject jsonObjectControl = new JSONObject();
jsonObjectControl.put("cmd","getdevice");
jsonObjectControl.put("uid",256);
jsonObject.put("control",jsonObjectControl);
json.put("json", jsonObject);
String encodedData = URLEncoder.encode( json.toString(), "UTF-8" );
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(httpRequest.getOutputStream()));
writer.write(encodedData);
writer.flush();
BufferedReader bufferedReader = null;
bufferedReader = new BufferedReader
(new InputStreamReader(httpRequest.getInputStream(), "UTF-8"));
String line = null;
StringBuilder sb = new StringBuilder();
do {
line = bufferedReader.readLine();
sb.append(line);
Log.i("Output line: ",sb.toString());
}
while(bufferedReader.readLine()!=null);
bufferedReader.close();
int responseCode = httpRequest.getResponseCode();
String resMsg = httpRequest.getResponseMessage();
String result = sb.toString();
Log.d("Output: ","--"+result);
Log.d("Response Code: "+responseCode, "!!");
Log.d("Response MSG ","--"+resMsg);
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}

HttpURLConnection GET request on Android gives weird 501 code

I have a weird issue when using HttpURLConnection on android it gives me a status code 501 but when I try the request on curl, it gives me status code 200.
curl -X GET \
-H "Accept-Charset: UTF-8" \
https://domain.com/v1/resource?token=token12345
This is my HttpURLConnection GET request snippet
public MyResponse get(String params) {
HttpURLConnection connection = null;
InputStreamReader inputStream = null;
BufferedReader reader = null;
MyResponse response = null;
String tokenParam = "?token=" + params;
try {
URL url = new URL(BASE_URL + API_VER + mResource + tokenParam);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod(Method.GET);
connection.setRequestProperty(Header.ACCEPT_CHARSET, Value.UTF_8);
connection.setDoInput(true);
connection.setDoOutput(true);
connection.connect();
int statusCode = connection.getResponseCode(); // code 501
inputStream = new InputStreamReader(connection.getInputStream());
reader = new BufferedReader(inputStream);
StringBuilder message = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
message.append(line);
}
response = new MyResponse();
response.setMessageBody(message.toString());
response.setStatusCode(statusCode);
if (statusCode == HTTP_OK || statusCode == HTTP_CREATED) {
response.setSuccess(true);
} else {
response.setSuccess(false);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) connection.disconnect();
try {
if (inputStream != null) inputStream.close();
if (reader != null) reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return response;
}
Am I missing anything?

setDoOutput(true) is used for POST and PUT requests for sending (output) a request body. Usually we don't need this for GET requests. Found it here

Ignore the timeout stuff if you don't need it.
The method at the bottom just takes an input stream and converts it into a response for you.
Hope it helps.
public boolean genLogon(){
HttpGet m_httpGet = null;
HttpResponse m_httpResponse = null;
// setup timeout params for the socket and the time to connect
HttpParams httpParameters = new BasicHttpParams();
int timeoutConnection = CONNECTION_TIMEOUT;
HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
int timeoutSocket = DATA_TIMEOUT;
HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
// Create a http client with the parameters
HttpClient m_httpClient = new DefaultHttpClient(httpParameters);
String result = null;
try {
// Create a get object
m_httpGet = new HttpGet("https://domain.com/v1/resource?token=token12345");
m_httpGet.setHeader(Accept-Charset, "UTF-8");
m_httpResponse = m_httpClient.execute(m_httpGet);
HttpEntity entity = m_httpResponse.getEntity();
if (entity != null) {
// Get the input stream and read it out into response
InputStream instream = entity.getContent();
result = convertStreamToString(instream);
// now you have the string representation of the HTML request
instream.close();
}
} catch (ConnectTimeoutException cte) {
// Toast.makeText(MainApplication.m_context, "Connection Timeout", Toast.LENGTH_SHORT).show();
return false;
} catch (Exception e) {
return false;
} finally {
m_httpClient.getConnectionManager().closeExpiredConnections();
}
// See if we have a response
if (m_httpResponse == null) {
return false;
}
// check status
if (m_httpResponse.getStatusLine() == null) {
return false;
}
// If the status code is okay (200)
if (m_httpResponse.getStatusLine().getStatusCode() == 200) {
//Handle the repsonse
return true
} else {
// response code not 200
}
return false;
}
private static String convertStreamToString(InputStream is) {
/*
* To convert the InputStream to String we use the BufferedReader.readLine() method. We iterate until the
* BufferedReader return null which means there's no more data to read. Each line will appended to a
* StringBuilder and returned as String.
*/
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}

Android POST Request 400 Response code throws Exception

When i send a POST Request to a Server, if the response is 200 i get the JSON body. However for unsuccessful requests the servers send a 400 response code but my android code throws a FileNotFoundException. Is there any difference between reading a 400 response and a 200 response ?
StringBuffer responseBuilder = new StringBuffer();
String line = null;
HttpURLConnection conn = null;
OutputStream out = null;
BufferedReader rd = null;
System.setProperty("http.keepAlive", "false");
try
{
conn = (HttpURLConnection) new URL(requestURL).openConnection();
conn.setRequestMethod("POST");
conn.setDoOutput(true);
conn.setDoInput(true);
conn.setUseCaches(false);
conn.setAllowUserInteraction(false);
conn.setConnectTimeout(NetworkConstants.CONNECTION_TIMEOUT);
conn.setReadTimeout(NetworkConstants.SOCKET_TIMEOUT);
out = conn.getOutputStream();
Writer writer = new OutputStreamWriter(out, "UTF-8");
String s = formatParams();
Log.d("-------------------------------------------------->", s);
writer.write(s);
writer.flush();
writer.close();
}
catch (Exception e)
{
}
finally
{
if (out != null)
{
try
{
out.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
try
{
rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = rd.readLine()) != null)
{
responseBuilder.append(line);
if (!rd.ready())
{
break;
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
if (conn != null)
{
conn.disconnect();
}
}
String response = responseBuilder.toString();
Log.d("###########################", response);
return response;
Kind Regards,

Use getErrorStream() for this. From the docs:
If the HTTP response indicates that an error occurred, getInputStream() will throw an IOException. Use getErrorStream() to read the error response. The headers can be read in the normal way using getHeaderFields().
Sample code:
httpURLConnection.connect();
int responseCode = httpURLConnection.getResponseCode();
if (responseCode >= 400 && responseCode <= 499) {
Log.e(TAG, "HTTPx Response: " + responseCode + " - " + httpURLConnection.getResponseMessage());
in = new BufferedInputStream(httpURLConnection.getErrorStream());
}
else {
in = new BufferedInputStream(httpURLConnection.getInputStream());
}
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line = "";
while ((line = reader.readLine()) != null) {
urlResponse.append(line);
}

If the response code isn't 200 or 2xx, use getErrorStream() instead of getInputStream() to parse the json and show the message provided by your backend.

I know it's been a long time since the question was asked but for the benefit of other people who are still having this kind of problem please note that another possible cause of the problem is using "connection.getContent()" to get InputStream. like so:
InputStream is = (InputStream) connection.getContent();
this can create a problematic situation where response code larger than 399 will not be processed at all.
so the recommendation is to work directly with getInputStream() and getErrorStream() as shown in previous comments and as in the following example:
HttpURLConnection connection = null;
BufferedReader bufferedReader = null;
try {
String urlString = "http://www.someurl.com";
URL url = new URL(urlString);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream is;
int responseCode = connection.getResponseCode();
if (responseCode < HttpURLConnection.HTTP_BAD_REQUEST) {
is = connection.getInputStream();
} else {
is = connection.getErrorStream();
}
StringBuilder response = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(is));
String tempLine;
while ((tempLine = bufferedReader.readLine()) != null) {
response.append(tempLine);
}
String serverResponse = response.toString();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (connection != null) {
connection.disconnect();
}
}

Android: Reading the HTML from a website and posting it to the screen

I'm aiming to make a very basic application which reads the HTML and stores it into a string. I'm only interested in one line from the website's source. I found a topic which suggested this:
String bodyHtml = "null";
try {
String myUri = "http://www.spring8.or.jp/ext/ja/status/text.html";
HttpClient httpClient = new DefaultHttpClient();
HttpGet get = new HttpGet(myUri);
HttpResponse response = httpClient.execute(get);
// Build up result
bodyHtml = EntityUtils.toString(response.getEntity());
} catch (Exception e) {
}
url.setText(bodyHtml);
With url being my textview. I have set the permissions in the manifest correctly as far as I'm aware.
However when I run this code on my phone and the emulator, it doesn't seem to work at all. I get nothing. Am I missing something?
Thank you

Try this instead of the EntityUtils
BufferedReader rd = new BufferedReader(new InputStreamReader(
response.getEntity().getContent()));
String line = "";
String newLine = "";
while ((line = rd.readLine()) != null) {
newLine = newLine.concat(line);
}
System.out.println(newLine);

Try this,
Call the below method to download the HTml Content and pass the Url in the parameter,
private void downloadText(String urlStr) {
progressDialog = ProgressDialog.show(this, "",
"Download Text from " + urlStr);
final String url = urlStr;
new Thread () {
public void run() {
int BUFFER_SIZE = 2000;
InputStream in = null;
Message msg = Message.obtain();
msg.what=1;
try {
in = openHttpConnection(url);
InputStreamReader isr = new InputStreamReader(in);
int charRead;
text = "";
char[] inputBuffer = new char[BUFFER_SIZE];
while ((charRead = isr.read(inputBuffer))>0)
{
String readString =
String.copyValueOf(inputBuffer, 0, charRead);
text += readString;
inputBuffer = new char[BUFFER_SIZE];
}
Bundle b = new Bundle();
b.putString("text", text);
msg.setData(b);
in.close();
}catch (IOException e2) {
e2.printStackTrace();
}
messageHandler.sendMessage(msg);
}
}.start();
}
This the helper method which returns InputStream Object,
private InputStream openHttpConnection(String urlStr) {
InputStream in = null;
int resCode = -1;
try {
URL url = new URL(urlStr);
URLConnection urlConn = url.openConnection();
if (!(urlConn instanceof HttpURLConnection)) {
throw new IOException ("URL is not an Http URL");
}
HttpURLConnection httpConn = (HttpURLConnection)urlConn;
httpConn.setAllowUserInteraction(false);
httpConn.setInstanceFollowRedirects(true);
httpConn.setRequestMethod("GET");
httpConn.connect();
resCode = httpConn.getResponseCode();
if (resCode == HttpURLConnection.HTTP_OK) {
in = httpConn.getInputStream();
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return in;
}
And now display the String in a textView using Handler,
private Handler messageHandler = new Handler() {
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1:
TextView text = (TextView) findViewById(R.id.textview01);
text.setText(msg.getData().getString("text"));
break;
}
progressDialog.dismiss();
}
};
Provide the INTERNET permission in the manifest.

In the execute method of the HttpClient, also put a HttpContext as you see below:
HttpContext localContext = new BasicHttpContext();
HttpResponse response = httpClient.execute(get, localContext);
And also use a BufferedReader:
final BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
If it doesn't work, you'll probably have a problem with you Internet connection.
BTW, don't forget about the android.permission.INTERNET permission!

Parse JSON from HttpURLConnection object

I am doing basic http auth with the HttpURLConnection object in Java.
URL urlUse = new URL(url);
HttpURLConnection conn = null;
conn = (HttpURLConnection) urlUse.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Content-length", "0");
conn.setUseCaches(false);
conn.setAllowUserInteraction(false);
conn.setConnectTimeout(timeout);
conn.setReadTimeout(timeout);
conn.connect();
if(conn.getResponseCode()==201 || conn.getResponseCode()==200)
{
success = true;
}
I am expecting a JSON object, or string data in the format of a valid JSON object, or HTML with simple plain text that is valid JSON. How do I access that from the HttpURLConnection after it returns a response?

You can get raw data using below method. BTW, this pattern is for Java 6. If you are using Java 7 or newer, please consider try-with-resources pattern.
public String getJSON(String url, int timeout) {
HttpURLConnection c = null;
try {
URL u = new URL(url);
c = (HttpURLConnection) u.openConnection();
c.setRequestMethod("GET");
c.setRequestProperty("Content-length", "0");
c.setUseCaches(false);
c.setAllowUserInteraction(false);
c.setConnectTimeout(timeout);
c.setReadTimeout(timeout);
c.connect();
int status = c.getResponseCode();
switch (status) {
case 200:
case 201:
BufferedReader br = new BufferedReader(new InputStreamReader(c.getInputStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line+"\n");
}
br.close();
return sb.toString();
}
} catch (MalformedURLException ex) {
Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
} finally {
if (c != null) {
try {
c.disconnect();
} catch (Exception ex) {
Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
}
}
}
return null;
}
And then you can use returned string with Google Gson to map JSON to object of specified class, like this:
String data = getJSON("http://localhost/authmanager.php");
AuthMsg msg = new Gson().fromJson(data, AuthMsg.class);
System.out.println(msg);
There is a sample of AuthMsg class:
public class AuthMsg {
private int code;
private String message;
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
JSON returned by http://localhost/authmanager.php must look like this:
{"code":1,"message":"Logged in"}
Regards

Define the following function (not mine, not sure where I found it long ago):
private static String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
Then:
String jsonReply;
if(conn.getResponseCode()==201 || conn.getResponseCode()==200)
{
success = true;
InputStream response = conn.getInputStream();
jsonReply = convertStreamToString(response);
// Do JSON handling here....
}

In addition, if you wish to parse your object in case of http error (400-5** codes),
You can use the following code: (just replace 'getInputStream' with 'getErrorStream':
BufferedReader rd = new BufferedReader(
new InputStreamReader(conn.getErrorStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = rd.readLine()) != null) {
sb.append(line);
}
rd.close();
return sb.toString();

The JSON string will just be the body of the response you get back from the URL you have called. So add this code
...
BufferedReader in = new BufferedReader(new InputStreamReader(
conn.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
That will allow you to see the JSON being returned to the console. The only missing piece you then have is using a JSON library to read that data and provide you with a Java representation.
Here's an example using JSON-LIB

This function will be used get the data from url in form of HttpResponse object.
public HttpResponse getRespose(String url, String your_auth_code){
HttpClient client = new DefaultHttpClient();
HttpPost postForGetMethod = new HttpPost(url);
postForGetMethod.addHeader("Content-type", "Application/JSON");
postForGetMethod.addHeader("Authorization", your_auth_code);
return client.execute(postForGetMethod);
}
Above function is called here and we receive a String form of the json using the Apache library Class.And in following statements we try to make simple pojo out of the json we received.
String jsonString =
EntityUtils.toString(getResponse("http://echo.jsontest.com/title/ipsum/content/ blah","Your_auth_if_you_need_one").getEntity(), "UTF-8");
final GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(JsonJavaModel .class, new CustomJsonDeserialiser());
final Gson gson = gsonBuilder.create();
JsonElement json = new JsonParser().parse(jsonString);
JsonJavaModel pojoModel = gson.fromJson(
jsonElementForJavaObject, JsonJavaModel.class);
This is a simple java model class for incomming json.
public class JsonJavaModel{
String content;
String title;
}
This is a custom deserialiser:
public class CustomJsonDeserialiserimplements JsonDeserializer<JsonJavaModel> {
#Override
public JsonJavaModel deserialize(JsonElement json, Type type,
JsonDeserializationContext arg2) throws JsonParseException {
final JsonJavaModel jsonJavaModel= new JsonJavaModel();
JsonObject object = json.getAsJsonObject();
try {
jsonJavaModel.content = object.get("Content").getAsString()
jsonJavaModel.title = object.get("Title").getAsString()
} catch (Exception e) {
e.printStackTrace();
}
return jsonJavaModel;
}
Include Gson library and org.apache.http.util.EntityUtils;