Netty4.X 获取客户端IP

2017年6月8日

最近使用netty-4.0.23.Final 版本编写服务端代码，有个获取客户端代码的小需求，以前使用servlet开发时很机械的就:

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6		 String ipAddr="0.0.0.0";
if (reqest.getHeader("X-Forwarded-For") == null) {
ipAddr = reqest.getRemoteAddr();
}else{
ipAddr = req.getHeader("X-Forwarded-For");
}

ps:X-Forwarded-For 是使用了代理（如nginx）会附加在HTTP头域上的。
理解好HTTP协议基础知识很重要这里不陈述。
Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序，支持多种协议，当然也支持HTTP协议。
启动Netty服务的程序：

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33		 public void start() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.option(ChannelOption.SO_BACKLOG, 1024);
bootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ServerHandlerInitializer());
Channel ch = bootstrap.bind(8080).sync().channel();
System.err.println("Open your web browser and navigate to "
+ ("http") + "://127.0.0.1:8080/");
ch.closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public class ServerHandlerInitializer extends ChannelInitializer<SocketChannel> {@Override
protected void initChannel(SocketChannel channel) throws Exception {
ChannelPipeline p = channel.pipeline();

p.addLast(new HttpRequestDecoder());
p.addLast(new HttpResponseEncoder());
p.addLast(new ServerHandler());
}

}

看出NioServerSocketChannel类的源码可以知道是对java.nio.channels.ServerSocketChannel重新封装，所以在获取客户端IP时调用remoteAddress()强转成java.net.InetSocketAddress即可获取。

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15		 public class ServerHandler extends SimpleChannelInboundHandler<HttpObject> {
@Override
public void channelRead0(ChannelHandlerContext ctx, HttpObject msg)
throws Exception {
if (msg instanceof HttpRequest) {
HttpRequest mReq = (HttpRequest) msg;
String clientIP = mReq.headers().get("X-Forwarded-For");
if (clientIP == null) {
InetSocketAddress insocket = (InetSocketAddress) ctx.channel()
.remoteAddress();
clientIP = insocket.getAddress().getHostAddress();
}
}
}
}

这样我们就可以获取到客户端的IP了。


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