A simple example of downloading file with Java outside of Selenium to workaround Selenium limitation in file downloads.

FileDownloader.java

/* an example of file download in Java w/ minimal amount of code, library imports, 
 * and object instantiations especially if you wrap/encapsulate code like example below.
 * NOTE: sample code has been tested to work but not thoroughly tested. Use at your own risk.
 */

import java.net.*;
import java.io.*;

//be sure to delete file after working with it. filenamePrefix ~ "test_", file extension ~ ".jpg", include the "."
public String downloadFile(String url, String filenamePrefix, String fileExtension) throws Exception{
  		//request setup...
  		URLConnection request = null;
  		request = new URL(url).openConnection();
		//extract session cookie from Selenium and use with HTTP request calls in Java
		//example below assumes server is running PHP hence we get PHP session ID
		//assumes you have direct access to WebDriver here
		request.setRequestProperty("Cookie", "PHPSESSID="+driver.manage().getCookieNamed("PHPSESSID").getValue());
		//add other headers as needed...
		//make the request to download file to disk as temp file and return path to file
		//can add a check for HTTP status code 200 if needed, but sample here skips, just check response output (file)
		InputStream in = request.getInputStream();
		File downloadedFile = File.createTempFile(filenamePrefix, fileExtension);
		FileOutputStream out = new FileOutputStream(downloadedFile);		
		byte[] buffer = new byte[1024];
		int len = in.read(buffer);
		while (len != -1) {
		    out.write(buffer, 0, len);
		    len = in.read(buffer);
		    if (Thread.interrupted()) {
		        throw new InterruptedException();
		    }
		}
		in.close();
		out.close();
		return downloadedFile.getAbsolutePath();
	}

This is simple working code. Can be fine tuned to do HTTP status code checking, do try/catch/finally error handling, and check that downloaded file is greater than 0 kb.

This is a simpler example to http://ardesco.lazerycode.com/index.php/2012/07/how-to-download-files-with-selenium-and-why-you-shouldnt/

for those that don't need the full features of that solution or have trouble integrating it into their code/framework.

How about multiple cookies?

I handle multiple cookies in the following way:

        HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
        Set<Cookie> cookies = driver.manage().getCookies();
        if (cookies != null) {
            StringBuilder cookiesString = new StringBuilder();
            for (Cookie cookie : cookies) {
                cookiesString.append(cookie.getName()).append("=").append(cookie.getValue()).append("; ");
            }
            connection.setRequestProperty("Cookie", cookiesString.toString());
        }