Develop Reference

How to correctly write POST request for a restheart on java

I am using restheart to provide a restful interface to mongodb. Get method is working good, I'm getting data from database in respons. But in this instance I'm trying to implementing POST request to write data in base. I'm running following code but I'm getting response with code 415 unsupported media type. My test base db1 have one collection testcoll where I'm trying to write a document with fields "name" and "rating"
public class PostMethodJava {
public static void main(String[] args) throws IOException {
URL url;
try {
url = new URL("http://127.0.0.1:8080/db1/testcoll/");
//url = new URL("http://google.com/");
} catch (Exception et) {
System.out.println("Data URL is broken");
return;
}
HttpURLConnection hc = null;
try {
hc = (HttpURLConnection) url.openConnection();
String login = "admin:12345678";
final byte[] authBytes = login.getBytes(StandardCharsets.UTF_8);
final String encoded = Base64.getEncoder().encodeToString(authBytes);
hc.addRequestProperty("Authorization", "Basic " + encoded);
System.out.println("Authorization: " + hc.getRequestProperty("Authorization"));
//hc.setDoInput(true);
hc.setDoOutput(true); //<== removed, otherwise 415 unsupported media type
hc.setUseCaches(false);
hc.setRequestMethod("POST");
//hc.setRequestProperty("Accept-Encoding", "gzip, deflate, sdch");
hc.setRequestProperty("Accept", "application/json");
} catch (Exception et) {
System.out.println("Can't prepare http URL con");
}
System.out.println(hc.toString());
String parameter = "mame=test1&rating=temp";
int plength = parameter.length();
byte[] pdata = parameter.getBytes(StandardCharsets.UTF_8);
try (DataOutputStream out = new DataOutputStream(hc.getOutputStream())){
out.write(pdata);
}
int rc = hc.getResponseCode();
System.out.println("response code: " + rc);
System.out.println("response message: " + hc.getResponseMessage());
}
}
What is wrong and how can I fix it?

Adding a line:
hc.setRequestProperty("Content-Type","application/json");
and writing the string:
String parameter = "{\"name\":\"doubleabc\",\"rating\":\"allright\"}";
fixed my problem.

HttpURLConnection always failing with 401

I'm trying to use HttpURLConnection for connecting to server from Android app which I'm developing. For now, I'm testing the connection code not in an app but as a plain java program with main class. I guess this doesn't make any difference as far as HttpUrlConnection.
Please examine the code snippet. Another issue is even errorStream is throwing null. This I feel is because of malformed URL.
private static String urlConnectionTry() {
URL url; HttpURLConnection connection = null;
try {
String urlParameters = "email=" + URLEncoder.encode("email", "UTF-8") +
"&pwd=" + URLEncoder.encode("password", "UTF-8");
//Create connection
url = new URL("http://example.com/login");
connection = (HttpURLConnection)url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
connection.setRequestProperty("uuid", getUuid());
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(true);
//Send request
DataOutputStream wr = new DataOutputStream (
connection.getOutputStream ());
wr.writeBytes (urlParameters);
wr.flush ();
wr.close ();
//Get Response
InputStream is = connection.getErrorStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while((line = rd.readLine()) != null) {
response.append(line);
response.append('\r');
}
rd.close();
return response.toString();
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if(connection != null) {
connection.disconnect();
}
}
}
private static String getUuid() {
try {
Document doc=Jsoup.connect("http://example.com/getUuid").get();
Elements metaElems = doc.select("meta");
for (Element metaElem : metaElems) {
if(metaElem.attr("name").equals("uuid")) {
return metaElem.attr("content");
}
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

You're probably receiving 401 because the credentials that was sent to the server is not authorized- it's probably not registered or the password is incorrect.
As for the null error stream, take a look at this SO answer.
If the connection was not connected, or if the server did not have an error while connecting or if the server had an error but no error data was sent, this method will return null.
It is probably better if you check first the response code using HttpUrlConnection#getResponseCode(). Decide on whether you'll be checking the contents of the error stream based on the response code you get.

Receiving null Value while using POST method in servlet?

I want to send a string by using POST method in servlet so that it can communicate with other servlet application present in other domain. But I am receiving null in my Input steam object.
My Code:
String content = "10 141 nahush123 01";
URL url = new URL("http://52.220.37.12:8080/servers/servers");
System.out.println(url.toString());
HttpURLConnection httpCon = (HttpURLConnection)url.openConnection();
httpCon.setDoInput(true);
httpCon.setDoOutput(true);
httpCon.setRequestMethod("POST");
httpCon.setRequestProperty("Content-Type", "text/plain;charset=UTF-8");
OutputStream os = httpCon.getOutputStream();
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(os));
out.write(content);
//br = BufferReader(out);
System.out.println(httpCon.getResponseCode());
System.out.println(httpCon.getResponseMessage());
writer.println(httpCon.getResponseMessage());
httpCon.connect();
br = new BufferedReader(new InputStreamReader(httpCon.getInputStream()));
//reading response
//String resp;
//if(br != null){
content = br.readLine();
//}
System.out.println(content);
writer.println(content);
out.flush();
writer.flush();
writer.close();
out.close();
os.close();

Copy pasted your code in my servlet worked fine
Check that you overrided doPost method in the servlet
Check that you that your post metod work fine and return value, I use "DHC Rest Client" plugin for chrome. It is very cool tool
Try to remove httpCon.connect() line. It is not necessary.
From oracle docs about connect() method:
Operations that depend on being connected, like getContentLength, will
implicitly perform the connection, if necessary.
Operations getResponseMessage, getResponseCode perform the connection.
UPDATED
I tried to test with my local test url and it works. Then i tried with your url and it does not work.
You need to flush output stream before use input stream.
This code work and return "0#5#26#Temperature#Living_Room#555555581#0+0#7#0#Room1#Master_bedroom#555555581#1+1#7#0#Door1#Living_Room#555555581#2+1#6#0#frontdoor#Living_Room#555555581#2+0#6#0#doorback#Balcony#555555581#2+"
PrintWriter writer = res.getWriter();
String content = "10 141 nahush123 01";
URL url = new URL("http://52.220.37.12:8080/servers/servers");
System.out.println(url.toString());
HttpURLConnection httpCon = (HttpURLConnection)url.openConnection();
httpCon.setDoInput(true);
httpCon.setDoOutput(true);
httpCon.setRequestMethod("POST");
httpCon.setRequestProperty("Content-Type", "text/plain;charset=UTF-8");
OutputStream os = httpCon.getOutputStream();
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(os));
out.write(content);
out.flush();
//br = BufferReader(out);
System.out.println(httpCon.getResponseCode());
System.out.println(httpCon.getResponseMessage());
writer.println(httpCon.getResponseMessage());
//httpCon.connect();
BufferedReader br = new BufferedReader(new InputStreamReader(httpCon.getInputStream()));
//reading response
//String resp;
//if(br != null){
content = br.readLine();
//}
System.out.println(content);
writer.println(content);
writer.flush();
writer.close();
out.close();
os.close();

Try with getparameter() function in the servlet

Call this method with your pass string parameter:
public String postData(String reqStr) {
ObjectOutputStream objOS = null;
ObjectInputStream objIS = null;
HttpURLConnection servletCon = null;
try {
if (reqStr != null) {
Thread.sleep(1000);
objOS.writeObject(reqStr);
} else {
throw new Exception("request is null.");
}
} catch (Exception ex) {
logger.error("Failed to send request to server.", ex);
}
String response = null;
try {
objIS = new ObjectInputStream(servletCon.getInputStream());
response = (String) objIS.readObject();
} catch (Exception ex) {
logger.error("Failed to get response from server.", ex);
response = null;
}
return response;
}
Initializing Connection like you but calling differently:
public void initializeUrlConnection(String servletURL, String contentType, String method) {
try {
logger.debug("Servlet URL " + servletURL);
url = new URL(servletURL);
servletCon = (HttpURLConnection) url.openConnection();
servletCon.setUseCaches(false);
servletCon.setDefaultUseCaches(false);
servletCon.setDoInput(true);
servletCon.setDoOutput(true);
servletCon.setRequestProperty("Content-Type", contentType);
servletCon.setRequestMethod(method);
objOS = new ObjectOutputStream(servletCon.getOutputStream());
} catch (IOException ex) {
logger.error("Failed to initialize Http Connection.", ex);
}
}
First of call initialize connection method with required parameter:
Object.initializeUrlConnection(url, contentType,method);
then call posDataMethod with your string/json parameter:
Object.postData(str);

HttpURLConnection 403 response after 200

Ok so I'm working on an app with 2 activities.
Let's call the 1st one LoginActivity which appears on top of my MainActivity. Also, I have a class SenderReceiver which extends AsyncTask that takes care of the connection to my https server.
The 1st time I call SenderReceiver from my LoginActivity, everything works fine & I get a 200 response & I'm able to use the JSON retrieved.
After that, the LoginActivity finishes & returns a result to the MainActivity. This is when I know I'm logged in & I can proceed.
Now whenever I execute SenderReceiver to get other information, I get the 403 response with a java.io.FileNotFoundException: https://url_of_my_server. But if I call the login again, it works.
Below is the SenderReceiver code snippet which connects to the server.
I'm also connecting to the same server on the iOS version of the app & never have issues with subsequent calls after the login.
Now this is my 1st time using https connections & such, I'm not really sure how it works on Android so I must be missing something or doing something wrong.
#Override
protected Boolean doInBackground(Object... params) {
frag = (Fragment)params[0]; // For later
addedParams = (List<NameValuePair>)params[1];
postPage = (String)params[2];
InputStream is = null;
try {
URL url = new URL(Constants.kWebService);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setUseCaches(false);
conn.setReadTimeout(15000);
conn.setConnectTimeout(20000);
conn.setRequestMethod("POST");
conn.setDoOutput(true);
//conn.setDoInput(true);
conn.setRequestProperty("CONTENT_TYPE", "application/json");
conn.setRequestProperty("X-requested-with", "XMLHttpRequest");
String base64EncodedCredentials = "Basic " + Base64.encodeToString((Constants.kHTTPSUser+":"+Constants.kHTTPSPass).getBytes(), Base64.NO_WRAP);
conn.setRequestProperty("Authorization", base64EncodedCredentials);
String param = "page="+postPage+"&";
for(int i = 0; i < addedParams.size(); i++) {
String and = (i < addedParams.size()-1)? "&": "";
param += addedParams.get(i).getName()+"="+ URLEncoder.encode(addedParams.get(i).getValue(), "UTF-8")+and;
}
conn.setFixedLengthStreamingMode(param.getBytes().length);
PrintWriter out = new PrintWriter(conn.getOutputStream());
out.print(param);
out.close();
// Starts the query
conn.connect();
int responseCode = conn.getResponseCode();
is = conn.getInputStream();
// Convert the InputStream into a string
responseSTR = Constants.inputStreamToString(is).toString();
return true;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} catch (ProtocolException pe) {
Constants.Log("Protocol Exception:"+pe.getMessage());
} catch (IOException io) {
Constants.Log("IO Exception:"+io.getMessage());
io.printStackTrace();
} finally {
if (is != null) {
try {
is.close();
} catch (IOException io) {
Constants.Log("is.close IO Exception:"+io.getMessage());
}
}
}
return false;
}

Fixed it!
All I had to do was to set the cookie header with:
conn.setRequestProperty("Cookie", Constants.kCookies);
& retrieve that cookie after the response in order to set it with:
List<String> cookies = conn.getHeaderFields().get("Set-Cookie");
if(cookies != null) {
Constants.kCookies = cookies.get(0);
}
That way in the initial HttpURLConnection connections (i.e:login) the cookie is empty & not needed. Once a connection is successful (after "login") it receives the cookie & sets it.
After that, any subsequent connection sends that cookie as part of the header.
The updated method below:
#Override
protected Boolean doInBackground(Object... params) {
frag = (Fragment)params[0];
addedParams = (List<NameValuePair>)params[1];
postPage = (String)params[2];
InputStream is = null;
try {
URL url = new URL(Constants.kWebService);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setUseCaches(false);
conn.setReadTimeout(15000);
conn.setConnectTimeout(20000);
conn.setRequestMethod("POST");
conn.setDoOutput(true);
//conn.setDoInput(true);
conn.setRequestProperty("CONTENT_TYPE", "application/json");
conn.setRequestProperty("X-requested-with", "XMLHttpRequest");
String base64EncodedCredentials = "Basic " + Base64.encodeToString((Constants.kHTTPSUser+":"+Constants.kHTTPSPass).getBytes(), Base64.NO_WRAP);
conn.setRequestProperty("Authorization", base64EncodedCredentials);
// Get the cookie from my Constants file & set it, Constants.kCookies is a static String
conn.setRequestProperty("Cookie", Constants.kCookies);
String param = "page="+postPage+"&";
for(int i = 0; i < addedParams.size(); i++) {
String and = (i < addedParams.size()-1)? "&": "";
param += addedParams.get(i).getName()+"="+ URLEncoder.encode(addedParams.get(i).getValue(), "UTF-8")+and;
}
conn.setFixedLengthStreamingMode(param.getBytes().length);
PrintWriter out = new PrintWriter(conn.getOutputStream());
out.print(param);
out.close();
// Starts the query
conn.connect();
int responseCode = conn.getResponseCode();
Constants.Log("The response code is: " + responseCode);
is = conn.getInputStream();
// Retrieve the cookie from the response & if not null save it to Constants.kCookies
List<String> cookies = conn.getHeaderFields().get("Set-Cookie");
if(cookies != null) {
Constants.kCookies = cookies.get(0);
}
// Convert the InputStream into a string
responseSTR = Constants.inputStreamToString(is).toString();//readIt(is, len);
return true;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} catch (ProtocolException pe) {
Constants.Log("Protocol Exception:"+pe.getMessage());
} catch (IOException io) {
Constants.Log("IO Exception:"+io.getMessage());
io.printStackTrace();
} finally {
if (is != null) {
try {
is.close();
} catch (IOException io) {
Constants.Log("is.close IO Exception:"+io.getMessage());
}
}
}
return false;
}

Parse.com REST API Error Code 400: Bad Request from Java HTTP Request to Cloud Function

I have a string that I am trying to send to a Parse.com cloud function. According to the REST API documentation (https://www.parse.com/docs/rest#general-requests), it must be in json format, so I made it into a json object and converted it to a string to append to the end of the http request url.
JSONObject jsonParam = new JSONObject();
jsonParam.put("emailId", emailId);
String urlParameters = jsonParam.toString();
Then I send the request as so, in my attempt to match their cURL code example as Java code:
con.setDoOutput(true);
DataOutputStream wr = null;
wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
Nonetheless, I receive a returned error code of 400 with error message "Bad Request", which I believe to be caused by unrecognizable parameters being sent to the cloud function. None of the other errors in my code trigger. Yet I verified through console logs that emailId is a normal string and the resulting JSON object, as well as its .toString() equivalent comes out as a proper string reading of a JSON object. Also this worked for another function I have in which I am creating an object in my Parse database. So why would it not work here?
Here is the full function for reference and context:
private void sendEmailWithParse(String emailId) throws IOException {
String url = "https://api.parse.com/1/functions/sendEmailNow";
URL obj = new URL(url);
HttpsURLConnection con = null;
try {
con = (HttpsURLConnection) obj.openConnection();
} catch (IOException e) {
System.out.println("Failed to connect to http link");
e.printStackTrace();
}
//add request header
try {
con.setRequestMethod("POST");
} catch (ProtocolException e) {
System.out.println("Failed to set to POST");
e.printStackTrace();
}
con.setRequestProperty("X-Parse-Application-Id", "**************************************");
con.setRequestProperty("X-Parse-REST-API-Key", "************************************************");
con.setRequestProperty("Content-Type", "application/json");
JSONObject jsonParam = new JSONObject();
jsonParam.put("emailId", emailId);
System.out.println("parameter being sent to cloud function: " + jsonParam);
System.out.println("parameter being sent to cloud function as string: " + jsonParam.toString());
String urlParameters = jsonParam.toString();
// Send post request
con.setDoOutput(true);
DataOutputStream wr = null;
try {
wr = new DataOutputStream(con.getOutputStream());
} catch (IOException e1) {
System.out.println("Failed to get output stream");
e1.printStackTrace();
}
try {
wr.writeBytes(urlParameters);
} catch (IOException e) {
System.out.println("Failed to connect to send over Parse object as parameter");
e.printStackTrace();
}
try {
wr.flush();
} catch (IOException e) {
e.printStackTrace();
}
try {
wr.close();
} catch (IOException e) {
System.out.println("Failed to connect to close datastream connection");
e.printStackTrace();
}
int responseCode = 0;
try {
responseCode = con.getResponseCode();
} catch (IOException e) {
System.out.println("Failed to connect to get response code");
e.printStackTrace();
}
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + urlParameters);
System.out.println("Response Code : " + responseCode);
System.out.println("Response message: " + con.getResponseMessage());
}

I solved the problem by using the HttpRequest external library. It gave me better control of the request and made for easier debugging of the problem. The server was receiving the request just fine, the problem was with the JSON encoding. Rather than putting the JSON object as a parameter in the request, I inserted it into the body of the http request and encoded it in UTF-8.
In the end, this is the code that worked:
String url = "https://api.parse.com/1/functions/sendEmailNow";
URL obj = new URL(url);
//Attempt to use HttpRequest to send post request to parse cloud
HttpRequest request = HttpRequest.post(obj).contentType("application/json");
request.header("X-Parse-Application-Id", "**************************");
request.header("X-Parse-REST-API-Key", "********************");
JSONObject jsonParam = new JSONObject();
jsonParam.put("emailId", emailId);
request.send(jsonParam.toString().getBytes("UTF8"));
if (request.ok())
System.out.println("HttpRequest WORKED");
else
System.out.println("HttpRequest FAILED " + request.code() + request.body());