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的值，而當我們使用dubbo+netty開發(fā)rest接口時，如果希望獲取IP地址，HttpServletRequest是用不了的，你需要使用netty中的NettyRequestFacade對象，這時，你之前的獲取IP地址的方法需要擴展，加一個只有入?yún)⒉灰粯樱a邏輯完成一樣的丑陋的，重復的代碼；這無疑是一種代碼的壞味道，應該想辦法解決它。

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，用來添加額外的功能，如獲取請求參數(shù)、session等信息。

為獲取IP地址添加包裝

自己的http請求包裝器接口RequestWrapper

public interface RequestWrapper {

	String getHeader(String name);

	String getRemoteAddr();

}

HttpServletRequest的包裝

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?yún)⑹且粋€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(jù)網(wǎng)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(diào)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));
}