How to submit a HTTP Request from a Java Program

Question

I am working on an web based application where in I need to submit the HttpRequest through a Java Program and not through browser. Moreover my intent is just to submit the HttpRequest. I donot want to wait for the response to come back. I have used the URL Connection class to do the same and I am trying to post this request. The contents of the methods that I am using are as below:-
public void doPost(URL url, String inputXMLString) throws IOException
          //Create URLConnection based on the passed URL
          URLConnection connection = url.openConnection();
          connection.setDoOutput(true);
          connection.setDoInput(false);
          connection.setUseCaches(false);
          connection.setAllowUserInteraction(false);
          connection.setRequestProperty("Content-type", "application/x-www-form-
urlencoded");
          //Get the Connection's output stream and write the request to it.
          PrintWriter out = new PrintWriter(connection.getOutputStream());
          out.print("&ena-request-input=" + URLEncoder.encode(inputXMLString));
          out.flush();
          out.close();
Call to the above method does not invoke the URL I am intending to submit the request at.
Can anybody give me the clue....................................................?

Answer 1

I agree with the advice to launch a new thread to read and ignore the response. I don't think you should have to do it to make it work, but it's worth trying for two reasons:
1) If it turns out it does make it work, well, then either you can leave it that way, or use that as a clue to help figure out how to make it work the way you want.
2) There may be an error message there that will give you an idea why it's not working.
When you say it's not invoking the servlet, what does that mean, and how do you know? Is it just that the final results aren't being seen? Put a bunch of logging statements in the servlet. It could be that it's getting hit, but you're corrupting the string you're building, or sending some extra junk that it can't handle. Spit out a log statement from the start of doPost, to see if it's even getting there. Then log the parameter. Enclose the output in quotes or braces or something to make sure there's not extra junk. I've had XML docs not parse because there was a blank line at the beginning.
If it works in the browser but not from your standalone app, then you need to have the servlet tell what difference it sees in the two cases. Print out headers, other params, everything you can think of.
Re-read the docs for URL, HttpURL, whatever, to make sure you're doing all the right steps in the right order. Make a servlet that just takes a single, simple param=value via POST and see if you can get that to work.