Setting user agent of a java URLConnection

Question

I\'m trying to parse a webpage using Java with URLConnection. I try to set up the user-agent like this:

java.net.URLConnection c = url.openConnection();
c.se         


        

Answer 1

Just for clarification: setRequestProperty("User-Agent", "Mozilla ...") now works just fine and doesn't append java/xx at the end! At least with Java 1.6.30 and newer.

I listened on my machine with netcat(a port listener):

$ nc -l -p 8080

It simply listens on the port, so you see anything which gets requested, like raw http-headers.

And got the following http-headers without setRequestProperty:

GET /foobar HTTP/1.1
User-Agent: Java/1.6.0_30
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

And WITH setRequestProperty:

GET /foobar HTTP/1.1
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

As you can see the user agent was properly set.

Full example:

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;


public class TestUrlOpener {

    public static void main(String[] args) throws IOException {
        URL url = new URL("http://localhost:8080/foobar");
        URLConnection hc = url.openConnection();
        hc.setRequestProperty("User-Agent", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2");

        System.out.println(hc.getContentType());
    }

}

Answer 2

HTTP Servers tend to reject old browsers and systems.

The page Tech Blog (wh): Most Common User Agents reflects the user-agent property of your current browser in section "Your user agent is:", which can be applied to set the request property "User-Agent" of a java.net.URLConnection or the system property "http.agent".

Answer 3

Off hand, setting the http.agent system property to "" might do the trick (I don't have the code in front of me).

You might get away with:

 System.setProperty("http.agent", "");

but that might require a race between you and initialisation of the URL protocol handler, if it caches the value at startup (actually, I don't think it does).

The property can also be set through JNLP files (available to applets from 6u10) and on the command line:

-Dhttp.agent=

Or for wrapper commands:

-J-Dhttp.agent=

Answer 4

its work for me set the User-Agent in the addRequestProperty.

URL url = new URL(<URL>);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
httpConn.addRequestProperty("User-Agent","Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0");