FileNotFoundException while getting the InputStream object from HttpURLConnection

Question

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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  quot Content-Type quot    quot application json  utf-8 quot    Full Script - gt  public class SendDeviceDetails extends AsyncTask lt String  Void  String gt      Override protected String doInBackground String    params         String data    quot  quot       String url    quot  quot        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  quot POST quot                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  quot Content-Type quot    quot application json  utf-8 quot              Set Response Format Type           Set the    Accept    request header to    application json    to read the response in the desired format          con setRequestProperty  quot Accept quot    quot application json quot               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  quot utf-8 quot                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     quot utf-8 quot                  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  quot TAG quot   result      this is expecting a response code to be sent from your server upon receiving the POST data    and call it new SendDeviceDetails   execute  quot  quot    you can find more details in this tutorial https   www baeldung com httpurlconnection-post

User · Answer

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

User · Answer

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

[java] FileNotFoundException while getting the InputStream object from HttpURLConnection

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