Sending parameters from servlets to URL via POST

[Arnob Dey]

The task is pretty simple. We just need to send some parameter values to a listener port on an URL via POST from the servlet. But for some reasons I can't get it to work. Is there anything I missed or doing it wrong entirely?

 public class SendToEMF extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
   
    public SendToEMF() {
        super();
     }

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		response.setContentType("text/html");
		
		try {

	   		URL url = new URL("http://XXX.XXX.XXX.XXX:1111/");

	   		HttpURLConnection con = (HttpURLConnection) url.openConnection();
	   		con.setRequestMethod("POST");
	   		
	   		con.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded"); 
	   		con.setRequestProperty( "charset", "utf-8");
	   		
	   		int responseCode = con.getResponseCode();
						
			if (HttpURLConnection.HTTP_OK == responseCode) 
			{ 
							
					
			String fileId = (String) request.getParameter("fileId");
				String filename = (String) request.getParameter("filename");
				String status = (String) request.getParameter("status");
				String reason = (String) request.getParameter("reason");
				
				String urlParams = "fileId="+fileId+"&filename="+filename+"&status="+status+"&reason="+reason;
				
				byte[] urlData = urlParams.getBytes(StandardCharsets.UTF_8);
				
				
				con.setDoOutput(true);
				
				DataOutputStream wr = new DataOutputStream(con.getOutputStream());
				wr.writeBytes(urlParams);
				
				wr.flush();
				wr.close();
				
			}
		 }
		catch(Exception e)
		{
				e.printStackTrace();
		}
	}
	
}
 

[Ron McLeod]

The problem is that you are sending your HTTP request  before adding your payload, resulting in a message exchange like this:POST / HTTP/1.1 Content-Type: application/x-www-form-urlencoded charset: utf-8 Host: XXX.XXX.XXX.XXX:1111 HTTP/1.1 200 OK Content-Length: 0

You should be calling getResponseCode() after setting your payload, which would result in a message exchange like this:POST / HTTP/1.1 Content-Type: application/x-www-form-urlencoded charset: utf-8 Host: XXX.XXX.XXX.XXX:1111 Content-Length: 71 fileId=my-fileId&filename=my-filename&status=my-status&reason=my-reason HTTP/1.1 200 OK Content-Length: 0

For example, using your code:

URL url = new URL("http://XXX.XXX.XXX.XXX:1111/");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
con.setRequestProperty("charset", "utf-8");

String fileId = "my-fileId";
String filename = "my-filename";
String status = "my-status";
String reason = "my-reason";
String urlParams = "fileId=" + fileId + "&filename=" + filename
		+ "&status=" + status + "&reason=" + reason;
// byte[] urlData = urlParams.getBytes(StandardCharsets.UTF_8);

con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(urlParams);
wr.flush();
wr.close();

int responseCode = con.getResponseCode(); // <===
if (HttpURLConnection.HTTP_OK == responseCode) {
	System.out.println("Successful");
} else {
	System.out.println("Failed!");
}

[Arnob Dey]

Thank you very much Ron .... really appreciate it...