Java获取客户端的真实IP地址

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;
  }