Sending Java POST request without calling getInputStream()

I would like to send a POST request in Java. At the moment, I do it like this:

U开发者_如何转开发RL url = new URL("myurl");
URLConnection con = url.openConnection();
con.setDoOutput(true);
PrintStream ps = new PrintStream(con.getOutputStream());
ps.println("key=" + URLEncoder.encode("value"));
// we have to get the input stream in order to actually send the request
con.getInputStream();  
ps.close();

I do not understand why I have to call con.getInputStream() in order to actually send the request. If I do not call it, the request is not sent.

Is there a problem using PrintStream? It should not matter if I take a PrintStream, PrintWriter or something else, right?

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URL represents some source.

URLConnection represents a connection to the resource.

you need call connection.connect() to connect the connection

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Try to add

con.setDoInput (false);

before writing to the output.

P.S.: and you should also call con.connect () as swanliu says.

Update
This is what I came up with

    private static final void sendPostRequest (final String urlAddress, String key, String value) throws Exception
    {
        URL url = new URL (urlAddress);
        URLConnection con = url.openConnection ();
        con.setDoOutput (true);
        con.setDoInput (false);
        PrintStream ps = new PrintStream (con.getOutputStream ());
        ps.println (key + "=" + URLEncoder.encode (value, "UTF-8"));
        ps.flush ();
        con.connect ();
        ps.close ();
    }

I checked with WireShark that a tcp connection is being established and that closed. But don't know how check that the server received the request. If you have a quick way to check it you may try that code.

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I think a post of another thread answered my question. Sorry, but I found it too late. You can find it here.

PS: Unfortunately, Stackoverflow added my last answer to the question as a comment, because my answer was too short. And it is not possible to mark a comment as the correct answer... Hope this one is long enough :-)

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I think this is the easiest way.

con.setDoOutput(true);
PrintStream ps = new PrintStream(con.getOutputStream());
ps.print("&client_id="+ 2);
ps.print("&amount="+10);
ps.flush();
ps.close();