java获取访问者主机名和IP地址

String ip = request.getHeader("x-forwarded-for"); 
if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) { 
    ip = request.getHeader("PRoxy-Client-IP"); 
} 
if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) { 
    ip = request.getHeader("WL-Proxy-Client-IP"); 
} 
if(ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) { 
    ip = request.getRemoteAddr(); 
} 
InetAddress a; 
try {  
a = InetAddress.getLocalHost(); 
System.out.println("主机名称: " + a.getHostName()+"ip:"+ip); 
} catch (Exception e) { 
}