Netty 实现HttpServer

　　使用Netty 实现一个简单的Http服务器，可以接受客户端的请求，并且实现拒绝请求一些请求，比如请求favicon.ico 网站图标的时候拒绝请求。

　　服务器收到客户端请求之后回传一个简单的消息： "hello, 我是服务器"

1. 代码

1. NettyHttpServerHandler

　　处理Http请求，如果不是Http请求则拒绝处理。

package netty;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.*;
import io.netty.util.CharsetUtil;

import java.net.URI;

public class NettyHttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {

    //channelRead0 读取客户端数据
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
        System.out.println("对应的channel=" + ctx.channel() + " pipeline=" + ctx
                .pipeline() + " 通过pipeline获取channel" + ctx.pipeline().channel());
        System.out.println("当前ctx的handler=" + ctx.handler());

        //判断 msg 是不是 httprequest请求
        if (msg instanceof HttpRequest) {
            System.out.println("ctx 类型=" + ctx.getClass());
            System.out.println("pipeline hashcode" + ctx.pipeline().hashCode() + " TestHttpServerHandler hash=" + this.hashCode());
            System.out.println("msg 类型=" + msg.getClass());
            System.out.println("客户端地址" + ctx.channel().remoteAddress());

            //获取到
            HttpRequest httpRequest = (HttpRequest) msg;
            //获取uri, 过滤指定的资源
            URI uri = new URI(httpRequest.uri());
            if ("/favicon.ico".equals(uri.getPath())) {
                System.out.println("请求了 favicon.ico, 不做响应");
                return;
            }
            //回复信息给浏览器 [http协议]

            ByteBuf content = Unpooled.copiedBuffer("hello, 我是服务器", CharsetUtil.UTF_8);
            //构造一个http的相应，即 httpresponse
            FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, content);
            response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html;charset=UTF-8");
            response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());

            //将构建好 response返回
            ctx.writeAndFlush(response);
        }
    }

}

2. NettyServerInitializer 初始化器

package netty;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;

public class NettyServerInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        // 向管道加入处理器
        // 得到管道
        ChannelPipeline pipeline = ch.pipeline();

        // 加入一个netty 提供的httpServerCodec codec =>[coder - decoder]
        // HttpServerCodec 说明
        //1. HttpServerCodec 是netty 提供的处理http的 编-解码器
        pipeline.addLast("MyHttpServerCodec", new HttpServerCodec());
        //2. 增加一个自定义的handler
        pipeline.addLast("MyTestHttpServerHandler", new NettyHttpServerHandler());

        System.out.println("ok~~~~");
    }
}

3. NettyHttpServer主类

package netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class NettyHttpServer {

    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).childHandler(new NettyServerInitializer());
            ChannelFuture channelFuture = serverBootstrap.bind(6565).sync();
            System.out.println("server is ok");
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

2. 测试

浏览器发送请求：

 服务器端日志如下：

ok~~~~
对应的channel=[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045] pipeline=DefaultChannelPipeline{(MyHttpServerCodec = io.netty.handler.codec.http.HttpServerCodec), (MyTestHttpServerHandler = netty.NettyHttpServerHandler)} 通过pipeline获取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
当前ctx的handler=netty.NettyHttpServerHandler@464839a5
ctx 类型=class io.netty.channel.DefaultChannelHandlerContext
pipeline hashcode55230216 TestHttpServerHandler hash=1179138469
msg 类型=class io.netty.handler.codec.http.DefaultHttpRequest
客户端地址/127.0.0.1:56045
对应的channel=[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045] pipeline=DefaultChannelPipeline{(MyHttpServerCodec = io.netty.handler.codec.http.HttpServerCodec), (MyTestHttpServerHandler = netty.NettyHttpServerHandler)} 通过pipeline获取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
当前ctx的handler=netty.NettyHttpServerHandler@464839a5
对应的channel=[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045] pipeline=DefaultChannelPipeline{(MyHttpServerCodec = io.netty.handler.codec.http.HttpServerCodec), (MyTestHttpServerHandler = netty.NettyHttpServerHandler)} 通过pipeline获取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
当前ctx的handler=netty.NettyHttpServerHandler@464839a5
ctx 类型=class io.netty.channel.DefaultChannelHandlerContext
pipeline hashcode55230216 TestHttpServerHandler hash=1179138469
msg 类型=class io.netty.handler.codec.http.DefaultHttpRequest
客户端地址/127.0.0.1:56045
请求了 favicon.ico, 不做响应
对应的channel=[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045] pipeline=DefaultChannelPipeline{(MyHttpServerCodec = io.netty.handler.codec.http.HttpServerCodec), (MyTestHttpServerHandler = netty.NettyHttpServerHandler)} 通过pipeline获取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
当前ctx的handler=netty.NettyHttpServerHandler@464839a5