Question

The following code exist on

http://docs.oracle.com/javase/tutorial/networking/urls/readingWriting.html

Which is the oracle tutorial website.

My problem is with understanding the servlet. As you can see in documentation at the bottom of the page it says:

If your ReverseServlet is located at http://example.com/servlet/ReverseServlet, then when you run the Reverse program using

http://example.com/servlet/ReverseServlet “Reverse Me”

To run this example I tested my program with this link

http://docs.oracle.com/javase/tutorial/networking/urls/examples/ReverseServlet.java “Reverse Me”

and I got this error:

Exception in thread "main" java.io.IOException: Server returned HTTP response code: 403 for URL: http://docs.oracle.com/javase/tutorial/networking/urls/examples/ReverseServlet.java
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1436)
    at DemoURL.main(DemoURL.java:28)

Is it the place that my ReverseServlet is located or I’m totally wrong. If this not the correct way how can I run this program to check this example in tutorial?

Here is the code I have changed the class name:

    import java.io.*;
    import java.net.*;
    public class DemoURL {
        public static void main(String[] args) throws Exception {

            if (args.length != 2) {
                System.err.println("Usage:  java Reverse "
                    + "http://<location of your servlet/script>"
                    + " string_to_reverse");
                System.exit(1);
            }

            String stringToReverse = URLEncoder.encode(args[1], "UTF-8");

            URL url = new URL(args[0]);
            URLConnection connection = url.openConnection();
            connection.setDoOutput(true);

            OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream());

            out.write("string=" + stringToReverse);
            out.close();



            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String decodedString;
            while ((decodedString = in.readLine()) != null) {
                System.out.println(decodedString);
            }
            in.close();

        }
    }

Answer 1

The url you use http://docs.oracle.com/javase/tutorial/networking/urls/examples/ReverseServlet.java does not contain a running version of the reverse servlet, just the source.

If you want to run the servlet you need to compile it and deploy the servlet yourself in a servlet container of your choice such as Tomcat, Jetty or similar. The servlet container handles accepting the request,parsing it and passing the request to the servlet.

Here is a description of how to (relatively) easily run a servlet Fastest way to deploy a Java servlet.