@Override
 protected void prepare(
     HttpMethod method, String uri, Map<String, String> extraHeaders, Map<String, String> data) {
   if (lastStatus != 302) {
     changeProxy();
   }
   super.prepare(method, uri, extraHeaders, data);
 }
 protected void changeProxy() {
   lock.readLock().lock();
   String proxyStr = proxypool.get(index.incrementAndGet() % proxypool.size());
   if (index.get() < 0) {
     index.set(0);
   }
   super.setProxy(proxyStr.split(":")[0], proxyStr.split(":")[1]);
   lock.readLock().unlock();
 }