Java Applet 411 Content Length

Question

I am new to Java. I wrote an applet with a gui that sends results (int w and int p) to a server, and I get the "411 Length Required" error. What am I doing wrong? How do you set a Content-Length?

This is the method that communicates with the server:

public void sendPoints1(int w, int p){

    try {
        String url = "http://somename.com:309/api/Results";
        String charset = "UTF-8";
        String query = String.format("?key=%s&value=%s",
            URLEncoder.encode(String.valueOf(w), charset),
            URLEncoder.encode(String.valueOf(p), charset));
        String length = String.valueOf((url + query).getBytes("UTF-8").length);

        HttpURLConnection connection = (HttpURLConnection) new URL(url + query).openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Length", length);
        connection.connect();
        System.out.println("Responce Code:    " + connection.getResponseCode());
        System.out.println("Responce Message: " + connection.getResponseMessage());
    } catch (Exception e) {
        System.err.println(e.getMessage());
    }

}

Answer 1

Request uri includes query , can use GET method.

connection.setRequestMethod("POST"); // modify to GET
connection.setRequestProperty("Content-Length", length); //remove the line

if use POST method, include 'content-length' heade, must send data.

for example:

public void sendPoints1(int w, int p){

    try {
        String url = "http://somename.com:309/api/Results";
        //value type is int ,don't need URLEncoder.
        byte[] data = ("key="+w+"&value="+p).getBytes("UTF-8");

        HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Length", data.length);
 connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); //URLencode...
        OuptputStream out = connection.getOutputStream();
        out.write(data);
        out.flush();
        InputStream in = connnection.getInputStream();
        //read .....
        System.out.println("Responce Code:    " + connection.getResponseCode());
        System.out.println("Responce Message: " + connection.getResponseMessage());
    } catch (Exception e) {
        System.err.println(e.getMessage());
    }

}

Answer 2

I'm not 100% sure why you're getting a 411 error code, but it probably has to do with the fact that you are not sending any content with your POST. The content-length header should be the length in bytes of the body of the request. You are setting it to the length of the url!

Either change the request to a GET or put the query into the body of the request instead of into the url itself. If you do the latter, set the content-length to the length of the body only.

public void sendPoints1(int w, int p){

    try {
        String url = "http://somename.com:309/api/Results";
        String charset = "UTF-8";
        String query = String.format("key=%s&value=%s",
            URLEncoder.encode(String.valueOf(w), charset),
            URLEncoder.encode(String.valueOf(p), charset));
        byte[] queryBytes = query.getBytes("UTF-8");
        String length = String.valueOf((url + query).getBytes("UTF-8").length);

        HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Length", length);
        OutputStream os = connection.getOutputStream();
        os.write(queryBytes);
        os.flush();
        connection.connect();
        System.out.println("Responce Code:    " + connection.getResponseCode());
        System.out.println("Responce Message: " + connection.getResponseMessage());
    } catch (Exception e) {
        System.err.println(e.getMessage());
    }

}

Answer 3

Since all information is passed as query string which is a part of URL, you need not setRequestMethod as POST. But if you still want to set it to POST as part of your logic, then setRequestProperty("Content-Length", "0") as Http Server expect Length to be read when POST method is called. In your case nothing is written as POST information so better set it to ZERO, even thought default value is ZERO at times server may give response errorCode as 411, response Message: Required Length