Netty 實現HttpServer

　　使用Netty 實現一個簡單的Http服務器，可以接受客戶端的請求，並且實現拒絕請求一些請求，比如請求favicon.ico 網站圖標的時候拒絕請求。

　　服務器收到客戶端請求之后回傳一個簡單的消息： "hello, 我是服務器"

1. 代碼

1. NettyHttpServerHandler

　　處理Http請求，如果不是Http請求則拒絕處理。

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 讀取客戶端數據
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
        System.out.println("對應的channel=" + ctx.channel() + " pipeline=" + ctx
                .pipeline() + " 通過pipeline獲取channel" + ctx.pipeline().channel());
        System.out.println("當前ctx的handler=" + ctx.handler());

        //判斷 msg 是不是 httprequest請求
        if (msg instanceof HttpRequest) {
            System.out.println("ctx 類型=" + ctx.getClass());
            System.out.println("pipeline hashcode" + ctx.pipeline().hashCode() + " TestHttpServerHandler hash=" + this.hashCode());
            System.out.println("msg 類型=" + msg.getClass());
            System.out.println("客戶端地址" + ctx.channel().remoteAddress());

            //獲取到
            HttpRequest httpRequest = (HttpRequest) msg;
            //獲取uri, 過濾指定的資源
            URI uri = new URI(httpRequest.uri());
            if ("/favicon.ico".equals(uri.getPath())) {
                System.out.println("請求了 favicon.ico, 不做響應");
                return;
            }
            //回復信息給瀏覽器 [http協議]

            ByteBuf content = Unpooled.copiedBuffer("hello, 我是服務器", CharsetUtil.UTF_8);
            //構造一個http的相應，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());

            //將構建好 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 {
        // 向管道加入處理器
        // 得到管道
        ChannelPipeline pipeline = ch.pipeline();

        // 加入一個netty 提供的httpServerCodec codec =>[coder - decoder]
        // HttpServerCodec 說明
        //1. HttpServerCodec 是netty 提供的處理http的 編-解碼器
        pipeline.addLast("MyHttpServerCodec", new HttpServerCodec());
        //2. 增加一個自定義的handler
        pipeline.addLast("MyTestHttpServerHandler", new NettyHttpServerHandler());

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

3. NettyHttpServer主類

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. 測試

瀏覽器發送請求：

 服務器端日志如下：

ok~~~~
對應的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)} 通過pipeline獲取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
當前ctx的handler=netty.NettyHttpServerHandler@464839a5
ctx 類型=class io.netty.channel.DefaultChannelHandlerContext
pipeline hashcode55230216 TestHttpServerHandler hash=1179138469
msg 類型=class io.netty.handler.codec.http.DefaultHttpRequest
客戶端地址/127.0.0.1:56045
對應的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)} 通過pipeline獲取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
當前ctx的handler=netty.NettyHttpServerHandler@464839a5
對應的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)} 通過pipeline獲取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
當前ctx的handler=netty.NettyHttpServerHandler@464839a5
ctx 類型=class io.netty.channel.DefaultChannelHandlerContext
pipeline hashcode55230216 TestHttpServerHandler hash=1179138469
msg 類型=class io.netty.handler.codec.http.DefaultHttpRequest
客戶端地址/127.0.0.1:56045
請求了 favicon.ico, 不做響應
對應的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)} 通過pipeline獲取channel[id: 0x0d2eb1d8, L:/127.0.0.1:6565 - R:/127.0.0.1:56045]
當前ctx的handler=netty.NettyHttpServerHandler@464839a5