Develop Reference

ERROR 411 consuming API in java (POST METHOD)

I am working on a personal project to learn how to work with Rest web services.
I have an API web application in Visual, which is my controller and where the connection to Oracle is made, and a web application in JAVA and with a JSON library, in addition to trying to do it in layers according to what I learned in the institute.
When I make the GET request, I have no problem, they bring me the data, but when I make a POST request as a customer's registrar it is when the problems start and I get the error 411 in java.
I Read looking for the solution that some worked for them by placing the "Content-Length" I don't know if I put it right but I still have the problem.
public int insertarCliente(Cliente c){
globalURL += "?rut=" + c.getRut() + "&nom="+ c.getNombre() +"&app=" + c.getApellidoP() + "&apm=" + c.getApellidoM();
try {
HttpURLConnection conn = Conectar(globalURL);
conn.setRequestMethod("POST");
conn.setRequestProperty("ACCEPT", "application/json");
conn.setRequestProperty("Content-Length", "0");
if (conn.getResponseCode() == 200) {
//InputStreamReader in = new InputStreamReader(conn.getInputStream());
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String resp = br.readLine();
JSONObject obj = new JSONObject(resp);
return obj.getInt("resp");
}
} catch (Exception e) {
Logger.getLogger(ClienteDAO.class.getName()).log(Level.SEVERE, null, e);
}
return 0;
}
The problem start in the IF.
And the error that shows me is the following:
Glook2 was successfully deployed in 227 milliseconds.
**Grave: java.lang.RuntimeException: Failed : HTTP Error code : 411**
at Controllers.ClienteDAO.insertarCliente(ClienteDAO.java:50)
at Services.cliente.registrar(cliente.java:104)
at Services.cliente.processRequest(cliente.java:46)
at Services.cliente.doPost(cliente.java:77)
I must emphasize that I have proven in the POSTMAN that the web services method works and correctly adds the data to the database.
String globalURL = "http://localhost:60367/api/Cliente";
HttpURLConnection conn;
public ClienteDAO() {
conn = Conectar(this.globalURL);
}
private HttpURLConnection Conectar(String urlRest) {
try {
URL url;
url = new URL(urlRest);
return (HttpURLConnection) url.openConnection();
} catch (Exception e) {
Logger.getLogger(ClienteDAO.class.getName()).log(Level.SEVERE, null, e);
}
return null;
}

Enable logging as shown here: How to enable wire logging for a java HttpURLConnection traffic?
You will then see1 that the Content-Length header is not sent:
FINE: sun.net.www.MessageHeader#4bf558aa5 pairs:
{POST / HTTP/1.1: null}
{ACCEPT: application/json}
{User-Agent: Java/13}
{Host: localhost:8080}
{Connection: keep-alive}
1: Sample log entry, wrapped for easier reading
That is because HttpURLConnection manages that header.
To send a Content-Length: 0 header, send no output, i.e. replace:
conn.setRequestProperty("Content-length", "0");
with:
conn.setDoOutput(true);
conn.getOutputStream().close();
Logging now shows the header:
FINE: sun.net.www.MessageHeader#5fa7e7ff7 pairs:
{POST / HTTP/1.1: null}
{ACCEPT: application/json}
{User-Agent: Java/13}
{Host: localhost:8080}
{Connection: keep-alive}
{Content-type: application/x-www-form-urlencoded}
{Content-Length: 0}
See also: JDK-6997628: HttpURLConnection strips Content-Length header on Post:
Affects Version/s: 6u22
Status: Open
Resolution: Unresolved
BT2:EVALUATION
The fix for CR 6961084 restricts the setting of some potentially security sensitive headers. Since these headers were allowed to be set in previous releases then of course compatibility is effected. A decision was made that compatibility was secondary to the security risk these headers posed. We understand that there may be valid apps out there that will be effected by this, so the sun.net.http.allowRestrictedHeaders property was added to revert to previous behavior.
BT2:WORK AROUND
Run with -Dsun.net.http.allowRestrictedHeaders=true
I would not recommend using that workaround.

HttpRequest from app engine endpoint. Connection reset

I am trying to send an HTTP request from an APP Engine endpoint, from experiments on Postman I know the result is quite big, and the the request usually takes about a minute.
here is my Code:
void testRequest() {
String test = getConnectionString();
URL url = new URL(YARDI_URL);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "text/xml");
connection.setConnectTimeout(1000000);
OutputStream os = connection.getOutputStream();
PrintWriter p = new PrintWriter(os);
p.print(test);
p.close();
YardiResponse response = new
YardiResponse(connection.getInputStream().toString());
System.out.println(response.getResponse());
connection.disconnect();
}
I am getting two errors,
the first is: java.net.ProtocolException: Cannot write output after reading input.
and after a long time I am getting a java.net.SocketException: Connection reset message.
Obviously I am mishandling the steams, and the way I send them.

I higly recomend http-request built on apache http api.
private static final HttpRequest<String.class> HTTP_REQUEST =
HttpRequestBuilder.createPost(YARDI_URL, String.class)
.responseDeserializer(ResponseDeserializer.ignorableDeserializer())
.contentTypeOfBody(ContentType.TEXT_XML)
.connectTimeout(someIntValue)
.socketTimeOut(someIntValue)
.connectionRequestTimeout(someIntValue).
.build();
void testRequest() {
ResponseHadler<String> yardiHandler = HTTP_REQUEST.executeWithBody(yourXml);
int statusCode = yardiHandler.getStatusCode();
String content = yardiHandler.get(); //returns response body as String in this case
}
Note: I recomend see javadocs of connectTimeout, socketTimeOut and connectionRequestTimeout methods.

Parse REST API, Validate User session

I am using Parse REST API for a game, altough there are java libraries for Parse I would like to handle the transfer protocolls my self using java.net for learning purposes. Please look away from things like, why dont I use Apache HttpClient.
Following the Parse REST API Guide
Here is what I am trying to achive:
Signup
User Login
validating session tokens / Retriving current user
The first two steps works just fine, the former using POST request method and the latter using GET with some paramaters.
Keeping the Request and Response format in mind I also provide the Application-ID and the REST-API-Key which are the appropriate request headers needed.
Now, for the third step using GET request with no paramaters, but with an additional header, the API expects there to be a Session-Token provided.
Code
private static void validateSessionToken(String token) throws IOException {
System.out.println("Token: " + token);
URL url = new URL("https://api.parse.com/1/users/me");
HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
con.setRequestMethod("GET");
con.setRequestProperty("X-Parse-Application-Id", "xxxxxxx");
con.setRequestProperty("X-Parse-REST-API-Key", "xxxxxxxx");
con.setRequestProperty("X-Parse-Session-Token", token);
con.setRequestProperty("content-type", "application/json");
int responseCode = con.getResponseCode();
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
if(responseCode == 400) {
System.out.println("Bad request!");
return;
}
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
System.out.println(response.toString());
}
Outputs
Sending 'GET' request to URL : https://api.parse.com/1/users/me
Response Code : 400
Bad request!
Debugging
I have been using the PARSE API CONSOLE and Chrome network debugging tool to try and see what the difference is, but cannot see any.
From wiki:
400 Bad Request
The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing)
Some photos that may help

So when I asked my JsonObject for the session token:
jsonObject.get("sessionToken").toString();
It returned: "r:WzB7qdmhkcW5qd2moM8gbBLDp" in quotation, but using:
jsonObject.get("sessionToken").getAsString();
it returned: r:WzB7qdmhkcW5qd2moM8gbBLDp
I was so focused on the request I did not even notice...

How to get redirect url on blackberry

I play a video url using streaming player on blackberry. If the url returns "200" status code it play successfully.
When i pass the below url, it returns "302" http status code.It won't play on streaming player.
http://belointr.rd.llnwd.net/KGW/ea398ac7b03a91c2ddf451f1fd7e3ef87f19da59_fl9.mp4?x-belo-vsect=kgw-basketball
When i check the statuscode for 302 its says redirect url.
When i pass the url on browser, it calls automatically below the redirect url.
http://belointr.vo.llnwd.net/kip0/_pxn=2+_pxI0=Ripod-h264+_pxL0=undefined+_pxM0=+_pxI1=A21907+_pxL1=begin+_pxM1=+_pxR1=13737+_pxK=20558/KGW/ea398ac7b03a91c2ddf451f1fd7e3ef87f19da59_fl9.mp4?x-belo-vsect=kgw-basketball
How can i get the redirect url programatically on blackberry.?
pls help me.

In the headers of the response, retrieve the value of the header 'Location', it contains the redirect url. This is standard in HTTP protocol
Edit: Real quick sample on how to get the location header (could be written a lot better and safer)
URL url = new URL("http://some.url");
int responseCode = -1;
while (responseCode != 200) {
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
responseCode = conn.getResponseCode();
if (responseCode > 299 && responseCode < 400) {
url = new URL(conn.getHeaderField("Location"));
}
}

FileNotFoundException while getting the InputStream object from HttpURLConnection

I am trying to send a post request to a url using HttpURLConnection (for using cUrl in java).
The content of the request is xml and at the end point, the application processes the xml and stores a record to the database and then sends back a response in form of xml string. The app is hosted on apache-tomcat locally.
When I execute this code from the terminal, a row gets added to the db as expected. But an exception is thrown as follows while getting the InputStream from the connection
java.io.FileNotFoundException: http://localhost:8080/myapp/service/generate
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1401)
at org.kodeplay.helloworld.HttpCurl.main(HttpCurl.java:30)
Here is the code
public class HttpCurl {
public static void main(String [] args) {
HttpURLConnection con;
try {
con = (HttpURLConnection) new URL("http://localhost:8080/myapp/service/generate").openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);
con.setDoInput(true);
File xmlFile = new File("test.xml");
String xml = ReadWriteTextFile.getContents(xmlFile);
con.getOutputStream().write(xml.getBytes("UTF-8"));
InputStream response = con.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(response));
for (String line ; (line = reader.readLine()) != null;) {
System.out.println(line);
}
reader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Its confusing because the exception is traced to the line InputStream response = con.getInputStream(); and there doesn't seem to be any file involved for a FileNotFoundException.
When I try to open a connection to an xml file directly, it doesn't throw this exception.
The service app uses spring framework and Jaxb2Marshaller to create the response xml.
The class ReadWriteTextFile is taken from here
Thanks.
Edit:
Well it saves the data in the DB and sends back a 404 response status code at the same time.
I also tried doing a curl using php and print out the CURLINFO_HTTP_CODE which turns out to be 200.
Any ideas on how do I go about debugging this ? Both service and client are on the local server.
Resolved:
I could solve the problem after referring to an answer on SO itself.
It seems HttpURLConnection always returns 404 response when connecting to a url with a non standard port.
Adding these lines solved it
con.setRequestProperty("User-Agent","Mozilla/5.0 ( compatible ) ");
con.setRequestProperty("Accept","*/*");

I don't know about your Spring/JAXB combination, but the average REST webservice won't return a response body on POST/PUT, just a response status. You'd like to determine it instead of the body.
Replace
InputStream response = con.getInputStream();
by
int status = con.getResponseCode();
All available status codes and their meaning are available in the HTTP spec, as linked before. The webservice itself should also come along with some documentation which overviews all status codes supported by the webservice and their special meaning, if any.
If the status starts with 4nn or 5nn, you'd like to use getErrorStream() instead to read the response body which may contain the error details.
InputStream error = con.getErrorStream();

FileNotFound is just an unfortunate exception used to indicate that the web server returned a 404.

To anyone with this problem in the future, the reason is because the status code was a 404 (or in my case was a 500). It appears the InpuStream function will throw an error when the status code is not 200.
In my case I control my own server and was returning a 500 status code to indicate an error occurred. Despite me also sending a body with a string message detailing the error, the inputstream threw an error regardless of the body being completely readable.
If you control your server I suppose this can be handled by sending yourself a 200 status code and then handling whatever the string error response was.

For anybody else stumbling over this, the same happened to me while trying to send a SOAP request header to a SOAP service. The issue was a wrong order in the code, I requested the input stream first before sending the XML body. In the code snipped below, the line InputStream in = conn.getInputStream(); came immediately after ByteArrayOutputStream out = new ByteArrayOutputStream(); which is the incorrect order of things.
ByteArrayOutputStream out = new ByteArrayOutputStream();
// send SOAP request as part of HTTP body
byte[] data = request.getHttpBody().getBytes("UTF-8");
conn.getOutputStream().write(data);
if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
Log.d(TAG, "http response code is " + conn.getResponseCode());
return null;
}
InputStream in = conn.getInputStream();
FileNotFound in this case was an unfortunate way to encode HTTP response code 400.

FileNotFound in this case means you got a 404 from your server - could it be that the server does not like "POST" requests?

FileNotFound in this case means you got a 404 from your server
You Have to Set the Request Content-Type Header Parameter
Set “content-type” request header to “application/json” to send the request content in JSON form.
This parameter has to be set to send the request body in JSON format.
Failing to do so, the server returns HTTP status code “400-bad request”.
con.setRequestProperty("Content-Type", "application/json; utf-8");
Full Script ->
public class SendDeviceDetails extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
String data = "";
String url = "";
HttpURLConnection con = null;
try {
// From the above URL object,
// we can invoke the openConnection method to get the HttpURLConnection object.
// We can't instantiate HttpURLConnection directly, as it's an abstract class:
con = (HttpURLConnection)new URL(url).openConnection();
//To send a POST request, we'll have to set the request method property to POST:
con.setRequestMethod("POST");
// Set the Request Content-Type Header Parameter
// Set “content-type” request header to “application/json” to send the request content in JSON form.
// This parameter has to be set to send the request body in JSON format.
//Failing to do so, the server returns HTTP status code “400-bad request”.
con.setRequestProperty("Content-Type", "application/json; utf-8");
//Set Response Format Type
//Set the “Accept” request header to “application/json” to read the response in the desired format:
con.setRequestProperty("Accept", "application/json");
//To send request content, let's enable the URLConnection object's doOutput property to true.
//Otherwise, we'll not be able to write content to the connection output stream:
con.setDoOutput(true);
//JSON String need to be constructed for the specific resource.
//We may construct complex JSON using any third-party JSON libraries such as jackson or org.json
String jsonInputString = params[0];
try(OutputStream os = con.getOutputStream()){
byte[] input = jsonInputString.getBytes("utf-8");
os.write(input, 0, input.length);
}
int code = con.getResponseCode();
System.out.println(code);
//Get the input stream to read the response content.
// Remember to use try-with-resources to close the response stream automatically.
try(BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream(), "utf-8"))){
StringBuilder response = new StringBuilder();
String responseLine = null;
while ((responseLine = br.readLine()) != null) {
response.append(responseLine.trim());
}
System.out.println(response.toString());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (con != null) {
con.disconnect();
}
}
return data;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
Log.e("TAG", result); // this is expecting a response code to be sent from your server upon receiving the POST data
}
and call it
new SendDeviceDetails().execute("");
you can find more details in this tutorial
https://www.baeldung.com/httpurlconnection-post

The solution:
just change localhost for the IP of your PC
if you want to know this: Windows+r > cmd > ipconfig
example: http://192.168.0.107/directory/service/program.php?action=sendSomething
just replace 192.168.0.107 for your own IP (don't try 127.0.0.1 because it's same as localhost)

Please change
con = (HttpURLConnection) new URL("http://localhost:8080/myapp/service/generate").openConnection();
To
con = (HttpURLConnection) new URL("http://YOUR_IP:8080/myapp/service/generate").openConnection();