Develop Reference

Encode and decode string with special chars in client-server application

I'm developing my client-server application (server is like a servlet and client is an Android app). I have some difficulties sending information between two entities when the message has special chars (ie: 'è' or others)
On client side I use this code to send the message that can contain special chars:
public static String effettuaPOSTServer (String parameters) {
try {
byte [] parametersBytes = parameters.getBytes("UTF-8");
URL url = new URL("http://" + IP_SERVER + ":" + PORT + PATH_SERVLET);
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
connection.setConnectTimeout(10000);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content_Type", "application/x-www-form-urlencoded; charset=utf-8");
connection.setRequestProperty ("Content-Length", String.valueOf (parametersBytes.length));
connection.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.write(parametersBytes);
wr.flush();
wr.close();
BufferedReader br = new BufferedReader (new InputStreamReader(connection.getInputStream(), "UTF-8"));
StringBuilder sb = new StringBuilder ();
String s;
while ((s = br.readLine ()) != null) {
sb.append (s);
sb.append ("\n");
}
return sb.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
on server side I use this code to send the response (also the response can contain special chars like 'è' and others) (I'm in servlet doPost context so I work with HttpServletRequest request and HttpServletResponse response):
PrintWriter pw = response.getWriter();
...
String content = ...; //the string is formatted in JSON format
pw.println (content);
but on both sides I'm unable to receive and manage the correct strings where I have special chars.
I'm trying a lot of solutions on web about encoding/decoding etc. but without successful result.
How can I fix my problem? Thank you!
EDIT:
for example, immagine my request from client as follow (I report the request in GET format to show simply the case):
http://MY_URL:PORT/MY_PATH?parameter1=value1&parameter2=value2&parameter3=èqualcosaacaso
but on server I receive:
parameter1=value1
parameter2=value2
parameter3=Äqualcosaacaso

HttpURLConnection: resulting json-code suggests page doesnt exist (404), even when url is correct

I am trying to get data from an MySQL database using a php-file. My java code is as follows:
HttpURLConnection conn = null;
URL url = null;
try {
url = new URL(getURL);
System.out.println(getURL);
conn = (HttpURLConnection)url.openConnection();
//conn.setReadTimeout(READ_TIMEOUT);
//conn.setConnectTimeout(CONNECTION_TIMEOUT);
conn.setRequestMethod("POST");
// setDoInput and setDoOutput method depict handling of both send and receive
conn.setDoInput(true);
conn.setDoOutput(true);
// Append parameters to URL
Uri.Builder builder = new Uri.Builder();
builder.appendQueryParameter("user", USER);
builder.appendQueryParameter("pass", PASS);
builder.appendQueryParameter("server", SERVER);
builder.appendQueryParameter("db", DB);
String query = builder.build().getEncodedQuery();
// Open connection for sending data
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
writer.write(query);
writer.flush();
writer.close();
os.close();
conn.connect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
try {
int response_code = conn.getResponseCode();
// Check if successful connection made
if (response_code == HttpURLConnection.HTTP_OK) {
// Read data sent from server
InputStream input = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
result = reader.readLine();
return(result);
}else{
return("unsuccessful");
}
When I go to my url (hidden in the variable getURL) using a browser, I see string of json on my screen, just as it should. However, when I output the contents of the reader (above code only takes the first line, but by adapting the code I can, of course, output more) it shows the html-code for a website displaying a 404 - Page does not exist message.
Anyone has any idea what goes wrong? Yes, I did check for typo's.

Okay, I have no clue what happened, as I didn't change anything. But all of the sudden it started working?!?
Must have been something server-side I guess...
Thanks for the input and sharing your thoughts!

Java app store receipt validation

I am trying to validate an Apple App Store receipt from a Java service. I can not get anything back other than an error 21002, "Receipt Data Property Was Malformed". I have read of others with the same problem, but, have not see a solution. I thought this would be fairly straight forward, but, have not been able to get around the error. Here is my code:
EDIT By making the change marked // EDIT below, I now get an exception in the return from the verifyReceipt call, also makred //EDIT:
String hexDataReceiptData = "<30821e3b 06092a86 4886f70d 010702a0 .... >";
// EDIT
hexDataReceiptData = hexDataReceiptData.replace(">", "").replace("<", "");
final String base64EncodedReceiptData = Base64.encode(hexDataReceiptData.getBytes());
JSONObject jsonObject = new JSONObject();
try
{
jsonObject.put("receipt-data",base64EncodedReceiptData);
}
catch (JSONException e)
{
e.printStackTrace();
}
URL url = new URL("https://sandbox.itunes.apple.com/verifyReceipt");
HttpURLConnection.setFollowRedirects(false);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
//Send request
OutputStreamWriter wr = new OutputStreamWriter(connection.getOutputStream());
wr.write(jsonObject.toString());
wr.flush();
//Get Response
BufferedReader rd =
new BufferedReader(new
InputStreamReader(connection.getInputStream()));
StringBuilder httpResponse = new StringBuilder();
String line;
while ((line = rd.readLine()) != null)
{
httpResponse.append(line);
httpResponse.append('\r');
}
wr.close();
rd.close();
// EDIT
// {"status":21002, "exception":"java.lang.IllegalArgumentException"}

As posted here: Java and AppStore receipt verification, do the base64 encoding in iOS and send to the server. But, why?

Simulate URL entering on java

So I have a problem where if I type this link on the browser and hit enter, an activation happens. I just want to do the same through Java. I don't need any kind of response from the URL. It should just do the same as entering the URL on a browser. Currently my code doesn't throw an error, but I don't think its working because the activation is not happening. My code:
public static void enableMachine(String dns){
try {
String req= "http://"+dns+"/username?username=sputtasw";
URL url = new URL(req);
URLConnection connection = url.openConnection();
connection.connect();
/*BufferedReader br = new BufferedReader(new InputStreamReader(url.openStream()));
String strTemp = "";
while (null != (strTemp = br.readLine())) {
System.out.println(strTemp);
}*/
} catch (Exception ex) {
ex.printStackTrace();
}
}
What's the problem?

If you want to do that with an URLConnection, it isn't sufficient to just open the connection with connect, you also have to send e.g. an HTTP request etc.
That said, i think it would be easier, if you use an HTTP client like the one from Apache HttpComponents (http://hc.apache.org/). Just do a GET request with the HTTP client, this would be the same as visiting the page with a browser (those clients usually also supports redirection etc.).

You may use HttpUrlConnectionClass to do the job:
URL url = new URL("http://my.url.com");
HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
httpCon.setRequestProperty("Content-Type", "application/json");
httpCon.setDoOutput(true);
httpCon.setRequestMethod("POST");
String params = "foo=42&bar=buzz";
DataOutputStream wr = new DataOutputStream(httpCon.getOutputStream());
wr.writeBytes(params);
wr.flush();
wr.close();
httpCon.connect();
int responseCode = httpCon.getResponseCode();
You may as well use "GET" request method and just append parameters to the url.

POST Requests from a Servlet

I am writing a servlet using eclipse that receives POST request from a client that should do some splitting on the received text, access google geolocation api to get some data and display to the user.
On a localhost, this works perfectly fine. On an actual server (tried with Openshift and CloudBees), this doesn't work. I can see the splitting reply but not the reply from google geolocation service. There is always an error logged into the console from google service. However, the same code works perfectly fine on localhost.
After I receive the POST request in the doPost method of the servlet, I am doing the following to access the Google GeoLocation service:
//Attempting to send data to Google Geolocation Service
URL url;
HttpURLConnection connection = null;
try {
//Create connection
url = new URL("https://www.googleapis.com/geolocation/v1/geolocate?key=MyAPI");
connection = (HttpURLConnection)url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/json");
connection.setUseCaches (false);
connection.setDoInput(true);
connection.setDoOutput(true);
//Send request with data (output variable has the JSON data)
DataOutputStream wr = new DataOutputStream (
connection.getOutputStream ());
wr.writeBytes (output);
wr.flush ();
wr.close ();
//Get Response
InputStream is = connection.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response2 = new StringBuffer();
while((line = rd.readLine()) != null) {
response2.append(line);
response2.append('\r');
}
rd.close();
//Write to Screen using out=response.getWriter();
out.println("Access Point's Location = " + response2.toString());
} catch (Exception e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.disconnect();
}
Could you tell me why this is happening and how can I make this work? Should I resort to something like AJAX or is there someother work around? I am relatively new to coding and hence, trying to refrain from learning AJAX at this stage. Please let me if there's any other way of getting this to work

Your localhost has your localhost IP as a sending IP. Openshift et al has the Openshift et al IP as a sending IP. So the Google API says "I have only seen that localhost IP twice before, that's fine!", whereas it says "I have seen this Openshift IP millions of times before! NO REPLY FOR YOU!"