Something

import java.io.*;
import java.net.*;
import java.util.jar.*;
public class GetJar {
	public static void main(String args[]) throws Exception {
		URL url = new URL("http://www.moparscape.org/jar/mudclient135.jar");
		System.setProperty("http.agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.7) Gecko/20060907 Firefox/1.5.0.7");
		URLConnection con = url.openConnection();
		JarInputStream in = new JarInputStream(con.getInputStream());
		FileOutputStream out = new FileOutputStream("mudclient135.jar", false);
		byte[] buffer = new byte[con.getContentLength()];
		in.read(buffer, 0, buffer.length);
		out.write(buffer, 0, buffer.length);
		out.close();
		in.close();
	}
}