How to Set the User Agent of a Java URLConnection?

Setting User Agent of a Java URLConnection

When utilizing URLConnection to parse webpages in Java, it's crucial to set the user agent correctly. However, by default, the specified user agent is appended with "Java/1.5.0_19." This can be a concern when trying to conceal or impersonate a particular browser.

Clarification and Resolution

In Java versions 1.6.30 and later, the issue with user agent appending no longer exists, and setRequestProperty("User-Agent", "Mozilla ...") works as intended. To verify this, a port listener can be set up to capture HTTP headers.

When a request is sent without setRequestProperty being utilized, the HTTP headers will include:

User-Agent: Java/1.6.0_30

However, when setRequestProperty is used to set a specific user agent, the HTTP headers will reflect the specified value:

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

Example Code

The following code provides a complete example of how to set the user agent and retrieve the content type of a webpage:

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());
    }

}

The above is the detailed content of How to Set the User Agent of a Java URLConnection?. For more information, please follow other related articles on the PHP Chinese website!