Netty構建Http服務器

時間 2019-11-08

原文原文鏈接

　　Netty 是一個基於 JAVA NIO 類庫的異步通訊框架，它的架構特色是：異步非阻塞、基於事件驅動、高性能、高可靠性和高可定製性。換句話說，Netty是一個NIO框架，使用它能夠簡單快速地開發網絡應用程序，好比客戶端和服務端的協議。Netty大大簡化了網絡程序的開發過程好比TCP和UDP的 Socket的開發。Netty 已逐漸成爲 Java NIO 編程的首選框架，Netty中，通信的雙方創建鏈接後，會把數據按照ByteBuf的方式進行傳輸，所以咱們在構建Http服務器的時候就是經過HttpRequestDecoder對ByteBuf數據流進行處理，轉換成http的對象。代碼以下：html

maven依賴java

<dependency>  
    <groupId>io.netty</groupId>  
    <artifactId>netty-all</artifactId>  
    <version>4.1.0.Final</version>  
</dependency>

HttpServer類編程

package com.example.demo.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;

public class HttpServer {

    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            pipeline.addLast(new HttpServerCodec());
                            pipeline.addLast(new HttpServerHandler());
                        }
                    });
            ChannelFuture f = b.bind(8080).sync();
            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }
}

HttpServerHandler類bootstrap

package com.example.demo.netty;

import java.io.UnsupportedEncodingException;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.QueryStringDecoder;

class HttpServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws UnsupportedEncodingException {

        if (msg instanceof HttpRequest) {

            // 請求，解碼器將請求轉換成HttpRequest對象
            HttpRequest request = (HttpRequest) msg;
            
            // 獲取請求參數
            QueryStringDecoder queryStringDecoder = new QueryStringDecoder(request.uri());
            String name = "netty";
            if(queryStringDecoder.parameters().get("name") != null) {
                    name = queryStringDecoder.parameters().get("name").get(0);
            }

            // 響應HTML
            String responseHtml = "<html><body>Hello, " + name + "</body></html>";
            byte[] responseBytes = responseHtml.getBytes("UTF-8");
            int contentLength = responseBytes.length;

            // 構造FullHttpResponse對象，FullHttpResponse包含message body
            FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, Unpooled.wrappedBuffer(responseBytes));
            response.headers().set("Content-Type", "text/html; charset=utf-8");
            response.headers().set("Content-Length", Integer.toString(contentLength));

            ctx.writeAndFlush(response);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}