Concurrency in urlconnection using multiple proxy server

Question

hi,
I am working on a web application project and need to set up different proxy server for different organization. I know that System.getProperties() will make proxy server work in urlconnection. However, since users from different organization may access our website concurrently, I think System.getProperties() needs to be synchronized through whole setting-proxy-properties----making-urlconnection----removing-proxy-properties working flow. so it will affect scalability of our website,right? any better solutions?
Thanks,
Dean

Answer 1

I just found a solution by subclassing sun package classes so that you can create url connection without affecting system.properties.
URL url =
new URL(null, urlSpec,
new ConcurrentProxyHandler(proxyHost,proxyPort));
//File: ConcurrentProxyHandler.java
//override connection of sun.net.www.protocol.http.HttpURLConnection import java.io.PrintStream;
import java.io.IOException;
import java.net.URL;
/** open an http input stream given a URL */
public class ConcurrentProxyHttpURLConnection extends
sun.net.www.protocol.http.HttpURLConnection {
protected ConcurrentProxyHttpURLConnection(URL u,
ConcurrentProxyHandler handler)
throws IOException {
super(u, handler);
public void connect() throws IOException {
if (connected) {
return;
try {
http = new sun.net.www.http.HttpClient(url,
((ConcurrentProxyHandler)handler).getProxy(),
((ConcurrentProxyHandler)handler).getProxyPort());
ps = (PrintStream)http.getOutputStream();
} catch (IOException e) {
throw e;
// constructor to HTTP client calls openserver
connected = true;
//File: ConcurrentProxyHandler.java
//override openConnection of sun.net.www.protocol.http.Handler and provide accessor for proxyHost
//and proxyPort
import java.io.IOException;
import java.net.URL;
public class ConcurrentProxyHandler extends sun.net.www.protocol.http.Handler {
public ConcurrentProxyHandler (String proxy, int port) {
super(proxy, port);
protected java.net.URLConnection openConnection(URL u)
throws IOException {
return new ConcurrentProxyHttpURLConnection(u, this);
protected String getProxy() {
return proxy;
protected int getProxyPort() {
return proxyPort;