JAVA获取请求的IP地址

private static final String[] ADDR_HEADER = { "X-Forwarded-For", "Proxy-Client-IP", "WL-Proxy-Client-IP",
            "X-Real-IP" };
    private static final String NUKNOWN = "unknown";



 /**
     * 获得真实IP地址。
     * 在使用了反向代理时，直接用HttpServletRequest.getRemoteAddr()无法获取客户真实的IP地址。
     * @param request 
     * @return
     */
    public static String getRemoteAddr(ServletRequest request) {
        String addr = null;
        if (request instanceof HttpServletRequest) {
            HttpServletRequest hsr = (HttpServletRequest) request;
            for (String header : ADDR_HEADER) {
                if (StringUtils.isBlank(addr) || NUKNOWN.equalsIgnoreCase(addr)) {
                    addr = hsr.getHeader(header);
                } else {
                    break;
                }
            }
        }
        if (StringUtils.isBlank(addr) || NUKNOWN.equalsIgnoreCase(addr)) {
            addr = request.getRemoteAddr();
        } else {
            // 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','分割
            if (addr != null) {
                int i = addr.indexOf(",");
                if (i > 0) {
                    addr = addr.substring(0, i);
                }
            }

        }
        return addr;
    }