跨域访问代理 --解决跨域访问问题

public class ProxyServlet extends HttpServlet {
@SuppressWarnings("unchecked")
@Override
protected void doGet(HttpServletRequest req,
HttpServletResponse resp) throws ServletException, IOException {
try {
StringBuffer query = new StringBuffer();
Enumeration e = req.getParameterNames();
while (e.hasMoreElements()) {
String s = e.nextElement();
if (s != null) {
query.append(s);
query.append("=");
query.append(req.getParameter(s));
query.append("&");
}
}
URL url = new URL("http://gdata.youtube.com/feeds/api/videos?" + query.toString());
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
BufferedReader in = new BufferedReader(new
InputStreamReader(connection.getInputStream()));
String decodedString;
StringBuffer sb = new StringBuffer();
while ((decodedString = in.readLine()) != null) {
sb.append(decodedString);
}
in.close();
resp.getOutputStream().print(sb.toString());
} catch (Exception e) {
}
}
}