Java 获取客户端IP

像移动网关一样，iisforward这个ISAPI过滤器也会对request对象进行再包装，附加一些WLS要用的头信息。这种情况下，直接用request.getRemoteAddr()是无法取到真正的客户IP的。

实际的iisforward附加头如下：

    WL-Proxy-Client-IP=211.161.1.239  
    Proxy-Client-IP=211.161.1.239  
    X-Forwarded-For=211.161.1.239  
    WL-Proxy-Client-Keysize=   
    WL-Proxy-Client-Secretkeysize=   
    X-WebLogic-Request-ClusterInfo=true  
    X-WebLogic-KeepAliveSecs=30  
    X-WebLogic-Force-JVMID=-327089098  
    WL-Proxy-SSL=false  

综上，正确作法如下：

private String getIpAddr() {   
     String ipAddress = null;   
     //ipAddress = this.getRequest().getRemoteAddr();   
     ipAddress = this.getRequest().getHeader("x-forwarded-for");   
     if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {   
      ipAddress = this.getRequest().getHeader("Proxy-Client-IP");   
     }   
     if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {   
         ipAddress = this.getRequest().getHeader("WL-Proxy-Client-IP");   
     }   
     if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {   
      ipAddress = this.getRequest().getRemoteAddr();   
      if(ipAddress.equals("127.0.0.1")){   
       //根据网卡取本机配置的IP   
       InetAddress inet=null;   
    try {   
     inet = InetAddress.getLocalHost();   
    } catch (UnknownHostException e) {   
     e.printStackTrace();   
    }   
    ipAddress= inet.getHostAddress();   
      }   
            
     }   
  
     //对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割   
     if(ipAddress!=null && ipAddress.length()>15){ //"***.***.***.***".length() = 15   
         if(ipAddress.indexOf(",")>0){   
             ipAddress = ipAddress.substring(0,ipAddress.indexOf(","));   
         }   
     }   
     return ipAddress;    
  }  

import javax.servlet.http.HttpServletRequest;

public class IpAddr {
    public static String getIpAddr(HttpServletRequest request) {
        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();
        }
        return ip;
    }
}