取得客户端真实IP
String ip = request.getHeader("x-forwarded-for");
request.getHeader("Proxy-Client-IP");
ip = request.getHeader("WL-Proxy-Client-IP");
ip = request.getRemoteAddr();


////
Enumeration names = request.getHeaderNames();
while(names.hasMoreElements()){
String str = (String)names.nextElement();
out.println("key:"+str+" value:"+request.getHeader(str)+"<br/>");
}