獲取IP地址信息時，一般我們需要一個HttpServletRequest對象，然后從請求頭里獲取x-forwarded-for的(de)值，而當我們使用(yong)dubbo+netty開發rest接口時，如果希(xi)望(wang)獲取IP地(di)址(zhi)，HttpServletRequest是用(yong)不了的(de)，你需(xu)要使用(yong)netty中的(de)NettyRequestFacade對象，這(zhe)時，你之前的(de)獲取IP地(di)址(zhi)的(de)方(fang)法需(xu)要擴展(zhan)，加一(yi)個只有(you)入參不一(yi)樣，代(dai)碼邏(luo)輯完成一(yi)樣的(de)丑(chou)陋的(de)，重復的(de)代(dai)碼；這(zhe)無(wu)疑是一(yi)種代(dai)碼的(de)壞(huai)味道(dao)，應該(gai)想辦法解決它。

適配器（包裝器）

這種常用的設計模式在spring框架里用的非常多，如ServletRequestAttributes,它包裝了HttpServletRequest和HttpServletResponse，用(yong)來添加(jia)額外(wai)的(de)功能，如獲取請求參數(shu)、session等信息。

為獲取IP地址添加包裝

自己的http請求包裝(zhuang)器接口RequestWrapper

public interface RequestWrapper {

	String getHeader(String name);

	String getRemoteAddr();

}

HttpServletRequest的(de)包裝(zhuang)

public class HttpRequestWrapper implements RequestWrapper {

	private final HttpServletRequest request;

	public HttpRequestWrapper(HttpServletRequest request) {
		this.request = request;
	}

	@Override
	public String getHeader(String name) {
		return request.getHeader(name);
	}

	@Override
	public String getRemoteAddr() {
		return request.getRemoteAddr();
	}

}

NettyRequestFacade的包裝

public class NettyRequestWrapper implements RequestWrapper {

	private final NettyRequestFacade request;

	public NettyRequestWrapper(NettyRequestFacade request) {
		this.request = request;
	}
	@Override
	public String getHeader(String name) {
		return request.getHeader(name);
	}

	@Override
	public String getRemoteAddr() {
		return request.getRemoteAddr();
	}

}

獲取IP地址方法，入參是一個http包裝器

public static String getIpAddr(RequestWrapper 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();
			if (ip.equals("127.0.0.1")) {
				// 根據網卡取本機配置的IP
				InetAddress inet = null;
				try {
					inet = InetAddress.getLocalHost();
				}
				catch (UnknownHostException e) {
					e.printStackTrace();
				}
				ip = inet != null ? inet.getHostAddress() : ip;
			}
		}
		// 對于通過多個代理的情況，第一個IP為客戶端真實IP,多個IP按照','分割
		if (ip != null && ip.length() > 15) {
			if (ip.indexOf(",") > 0) {
				ip = ip.substring(0, ip.indexOf(","));
			}
		}
		if ("0:0:0:0:0:0:0:1".equals(ip)) {
			ip = "127.0.0.1";
		}
		return ip;
	}

調用示例：

// 使用HttpServletRequest
public String getIpFromHttp(HttpServletRequest request) {
    return getIpAddr(new HttpRequestWrapper(request));
}

// 使用NettyRequestFacade
public String getIpFromNetty(NettyRequestFacade request) {
    return getIpAddr(new NettyRequestWrapper(request));
}