Netty acquaintance

What is Netty

　　References: Time Geeks Fu Jian teacher "Netty source code analysis and practical" Talk is cheap.show me the code!

　　Official website ( https://netty.io/ ) indicates that: "Netty is an asynchronous event- driven network application framework for rapid development of maintainable high performance protocol servers & clients.", Translates to: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high-performance protocol servers and clients. Simple split can be understood:

① nature: web application framework

② implementation: asynchronous, event-driven

③ characteristics: high performance, maintenance, rapid development

④ purposes: to develop server and client

 　　This is the official website of a structure to chart:

 

Nettty difficult to see a total of three parts, the bottom layer is the core, from the bottom up, the bottom is "zero copy Buffer", a grid is up "the API communication layer", and then the grid is a "expansion the event model ", top left is the transport layer services, including the Http Tunnel, TCP's Socket, UDP Datagram so on the upper right is Netty support a variety of protocols, such as we often say that the HTTP protocol, WebSocket protocol, Google's ProtoBuf agreement and so on.

The first HelloWorld

　　Build a project with Maven InterlliJ IDEA, Netty added in pom.xml configuration file dependency

　　　　<dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.10.Final</version>
        </dependency>

 

Server-side MyService.java

package com.lql.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.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

/**
 * @author: lql
 * @date: 2019.10.14
 * Description:     第一个Netty程序     服务器
 */
public class MyServer {


    public static void main(String[] args) throws Exception {

        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap sb = new ServerBootstrap();
            sb.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ChannelPipeline p = ch.pipeline();
                    p.addLast(new LoggingHandler(LogLevel.INFO));
                    p.addLast(new MyServerHandler());
                }
            });

            ChannelFuture f = sb.bind(8090).sync();
            f.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }
}

 

Write MyServerHandler.java

package com.lql.netty;

import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

/**
 * @author: lql
 * @date: 2019.10.14
 * Description:
 */
@Sharable
public class MyServerHandler extends ChannelInboundHandlerAdapter {


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

        ctx.write(msg);
    }


    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {

        cause.printStackTrace();
        ctx.close();
    }
}

 

Again write a client MyClient.java

package com.lql.netty;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

/**
 * @author: lql
 * @date: 2019.10.14
 * Description: 第一个Netty程序     客户端
 */
public class MyClient {

    public static void main(String[] args) throws Exception {
        //客户端只需要一个事件循环组
        EventLoopGroup group = new NioEventLoopGroup();

        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline p =socketChannel.pipeline (); 
                            p.addLast ( new new LoggingHandler (LogLevel.INFO)); 
                            p.addLast ( new new MyClientHandle ()); 
                        } 
                    }); 

            // start client 
            ChannelFuture f = b.connect ( "127.0.0.1" , 8090 ) .sync ();
             // wait for the connection is closed 
            f.channel () closeFuture () Sync ();.. 

        } the finally {
             // elegant closed 
            group.shutdownGracefully (); 
        } 

    } 
}

 

Similarly, create MyClientHandle.java

package com.lql.netty;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.util.concurrent.TimeUnit;

/**
 * @author: lql
 * @date: 2019.10.14
 * Description:
 */
public class MyClientHandle extends ChannelInboundHandlerAdapter{

    private final ByteBuf firstMessage;

    public MyClientHandle() {
        firstMessage = Unpooled.wrappedBuffer("I am echo message".getBytes());
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(firstMessage);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ctx.write(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        ctx.flush();
    }

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

 

Start the server, start the client, the result is feasible!

Netty and Spring mvc also be the same. As follows:

Establish HttpServer.java

package com.lql.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.HttpServerExpectContinueHandler;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

/**
 * @author: lql
 * @date: 2019.10.14
 * Description:
 * Created with IntelliJ IDEA
 */
public class HttpServer {


    public static void main(String[] args) throws Exception {

        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer() {
                        protected void initChannel(Channel ch) throws Exception {
                            ChannelPipeline p = ch.pipeline();
                            p.addLast(new HttpServerCodec());
                            p.addLast(new HttpServerExpectContinueHandler());
                            p.addLast(new HttpServerHandler());
                        }
                    });

            ChannelFuture channelFuture = b.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();

        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

 

Re-establish HttpServerHandler.java

 

package com.lql.netty;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.*;

/**
 * @author: lql
 * @date: 2019.10.14
 * Description:
 * Created with IntelliJ IDEA
 */
public class HttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {


    private static final byte[] CONTENT = "helloworld".getBytes();

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    @Override
    public void channelRead0(ChannelHandlerContext ctx, HttpObject msg) {
        if (msg instanceof HttpRequest) {
            HttpRequest req = (HttpRequest) msg;

            FullHttpResponse response = new DefaultFullHttpResponse(req.protocolVersion(), HttpResponseStatus.OK,
                    Unpooled.wrappedBuffer(CONTENT));
            response.headers()
                    .set(HttpHeaderNames.CONTENT_TYPE, "text/plain")
                    .setInt(HttpHeaderNames.CONTENT_LENGTH, response.content().readableBytes());
            ctx.write(response);
        }
    }

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

Start HttpServer: URL input " HTTP: // localhost: 8899 / ", shown below:

At this point, Netty's HelloWorld has finished!