java - How to send post request with x-www-form-urlencoded body -

how in java, can send request x-www-form-urlencoded header. don't understand how send body key-value, in above screenshot.

i have tried code:

string urlparameters =   cafedra_name+ data_to_send; url url;     httpurlconnection connection = null;       try {       //create connection       url = new url(targeturl);       connection = (httpurlconnection)url.openconnection();       connection.setrequestmethod("post");       connection.setrequestproperty("content-type",             "application/x-www-form-urlencoded");        connection.setrequestproperty("content-length", "" +                 integer.tostring(urlparameters.getbytes().length));       connection.setrequestproperty("content-language", "en-us");          connection.setusecaches (false);       connection.setdoinput(true);       connection.setdooutput(true);        //send request       dataoutputstream wr = new dataoutputstream (                   connection.getoutputstream ());       wr.writebytes (urlparameters);       wr.flush ();       wr.close (); 

but in response, don't receive correct data.

as set application/x-www-form-urlencoded content type data sent must format.

string urlparameters  = "param1=data1&param2=data2&param3=data3"; 

sending part quite straightforward.

byte[] postdata = urlparameters.getbytes( standardcharsets.utf_8 ); int postdatalength = postdata.length; string request = "<url here>"; url url = new url( request ); httpurlconnection conn= (httpurlconnection) url.openconnection();            conn.setdooutput(true); conn.setinstancefollowredirects(false); conn.setrequestmethod("post"); conn.setrequestproperty("content-type", "application/x-www-form-urlencoded");  conn.setrequestproperty("charset", "utf-8"); conn.setrequestproperty("content-length", integer.tostring(postdatalength )); conn.setusecaches(false); try(dataoutputstream wr = new dataoutputstream(conn.getoutputstream())) {    wr.write( postdata ); } 

or can create generic method build key value pattern required application/x-www-form-urlencoded.

private string getdatastring(hashmap<string, string> params) throws unsupportedencodingexception{     stringbuilder result = new stringbuilder();     boolean first = true;     for(map.entry<string, string> entry : params.entryset()){         if (first)             first = false;         else             result.append("&");             result.append(urlencoder.encode(entry.getkey(), "utf-8"));         result.append("=");         result.append(urlencoder.encode(entry.getvalue(), "utf-8"));     }         return result.tostring(); }