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;
    }
}