Netty简单入门代码案例

于 2019-06-30 16:56:14 发布
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分类专栏： Netty 文章标签： netty
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本文链接：https://blog.youkuaiyun.com/kkagr/article/details/94293500
本文通过五个具体的案例，逐步介绍Netty的基础使用，包括Http编程、Socket编程、聊天室实现、读写检测以及长连接的创建。每个案例都包含服务端和客户端的实现，详细展示了Netty在不同场景下的应用。

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首先我们用maven来构建Netty
引入pom配置

<dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
        <version>4.1.36.Final</version>
    </dependency>

目录结构
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案例1 Netty Http编程
首先新建一个TestService

package com.kkagr.netty.firstExample;

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

        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workGroup).channel(NioServerSocketChannel.class)
            .childHandler(new TestServerinitializer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
}

TestHttpServerHandler

package com.kkagr.netty.firstExample;


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.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpObject;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.CharsetUtil;
public class TestHttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, HttpObject msg) throws Exception {
        if(msg instanceof HttpRequest){
            HttpRequest httpRequest = (HttpRequest)msg;
            System.out.println("请求方法名"+httpRequest.method().name());
            ByteBuf content = Unpooled.copiedBuffer("hello word", CharsetUtil.UTF_8);
            FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,HttpResponseStatus.OK,content);
            response.headers().set(HttpHeaderNames.CONTENT_TYPE,"text/plain");
            response.headers().set(HttpHeaderNames.CONTENT_LENGTH,content.readableBytes());
            channelHandlerContext.writeAndFlush(response);
        }

    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelActive");
        super.channelActive(ctx);
    }

    @Override
    public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelRegistered");
        super.channelRegistered(ctx);
    }

    @Override
    public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelUnregistered");
        super.channelUnregistered(ctx);
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelInactive");
        super.channelInactive(ctx);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelReadComplete");
        super.channelReadComplete(ctx);
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        System.out.println("userEventTriggered");
        super.userEventTriggered(ctx, evt);
    }

    @Override
    public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
        System.out.println("channelWritabilityChanged");
        super.channelWritabilityChanged(ctx);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        System.out.println("exceptionCaught");
        super.exceptionCaught(ctx, cause);
    }
}

TestServerinitializer

package com.kkagr.netty.firstExample;

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 TestServerinitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline =socketChannel.pipeline();
        //编码解码合二为一
        pipeline.addLast("httpServerCodec",new HttpServerCodec());
        pipeline.addLast("testHttpServerHandler",new TestHttpServerHandler());
    }
}

启动main方法，在浏览器输入http://localhost:8899/
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服务端返回
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案例二:Netty Socket编程

MyServer

package com.kkagr.netty.secondExample;

import sun.rmi.server.LoaderHandler;

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 MyServer {
    public static void main(String[] args) {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workGroup).channel(NioServerSocketChannel.class).
                    childHandler(new MyServerInitailizer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (Exception e){
            e.printStackTrace();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }

}

MyServerInitailizer

package com.kkagr.netty.secondExample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class MyServerInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel socketChannel) {
        ChannelPipeline pipeline = socketChannel.pipeline();
        pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
        pipeline.addLast(new LengthFieldPrepender(4));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyServerHandler());
    }
}

MyServerHandler

package com.kkagr.netty.secondExample;

import java.util.UUID;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class MyServerHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception {
        System.out.println(channelHandlerContext.channel().remoteAddress()+","+s);
        channelHandlerContext.channel().writeAndFlush("from service"+UUID.randomUUID());
    }
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("来自服务端的问候");
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

MyClient

package com.kkagr.netty.secondExample;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

public class MyClient {
    public static void main(String[] args){
        EventLoopGroup  eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class).handler(new MyClientInitailizer());
            ChannelFuture channelFuture = bootstrap.connect("localhost",8899).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (Exception e){
            e.printStackTrace();
        }
        finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

MyClientInitailizer

package com.kkagr.netty.secondExample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class MyClientInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE,0,4,0,4));
        pipeline.addLast(new LengthFieldPrepender(4));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyClientHandler());
    }
}

MyClientHandler

package com.kkagr.netty.secondExample;

import java.util.Date;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class MyClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
        System.out.println(ctx.channel().remoteAddress());
        System.out.println("client output"+s);
        ctx.writeAndFlush("from client:"+new Date());

    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("来自客户端的问候");
        ctx.writeAndFlush("from client:"+new Date());
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

启动service和client
返回
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案例三 聊天室

MyChatServer

package com.kkagr.netty.thirtyExample;

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;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public class MyChatServer {
    public static void main(String[] args) throws Exception{
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workGroup).channel(NioServerSocketChannel.class).
                    childHandler(new MyChatServerInitailizer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
}

MyChatServerInitailizer

package com.kkagr.netty.thirtyExample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class MyChatServerInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096,Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyChatServerHandler());
    }
}

MyChatServerHandler

package com.kkagr.netty.thirtyExample;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;

public class MyChatServerHandler extends SimpleChannelInboundHandler<String> {

    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        final Channel channel = ctx.channel();
        channelGroup.forEach(ch->{
            if(channel != ch){
                ch.writeAndFlush(channel.remoteAddress()+"发送消息："+msg+"\n");
            }else{
                ch.writeAndFlush("【自己】"+msg+"\n");
            }
        });


    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("【服务器】-"+channel.remoteAddress()+"加入\n");
        channelGroup.add(channel);
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("【服务器】-"+channel.remoteAddress()+"离开\n");
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress()+"上线");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress()+"下线");
    }

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

    }
}

MyCahtClient

package com.kkagr.netty.thirtyExample;

import com.kkagr.netty.secondExample.MyClientInitailizer;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

public class MyCahtClient {
    public static void main(String[] args) throws Exception{
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    .handler(new MyCahtClientInitailizer());
            Channel channel = bootstrap.connect("localhost",8899).channel();
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            for(;;){
                channel.writeAndFlush(br.readLine()+"\r\n");
            }
        }finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

MyCahtClientInitailizer

package com.kkagr.netty.thirtyExample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class MyCahtClientInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096,Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyChatClientHandler());
    }
}

MyChatClientHandler

public class MyChatClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }
}

在这里插入图片描述
在这里插入图片描述
如果打不开两个客户端
在这里插入图片描述
案例四：读写检测
MyServer

package com.kkagr.netty.fourExample;

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;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public class MyServer {
    public static void main(String[] args) throws Exception{
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workGroup).channel(NioServerSocketChannel.class).
                    handler(new LoggingHandler(LogLevel.INFO)).
                    childHandler(new MyServerInitailizer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
}

MyServerInitailizer

package com.kkagr.netty.fourExample;

import java.util.concurrent.TimeUnit;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import io.netty.util.CharsetUtil;

public class MyServerInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new IdleStateHandler(5,7,10,TimeUnit.SECONDS));
        pipeline.addLast(new MyServerHandler());
    }
}

MyServerHandler

package com.kkagr.netty.fourExample;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.timeout.IdleStateEvent;
import io.netty.util.concurrent.GlobalEventExecutor;

public class MyServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if(evt instanceof IdleStateEvent){
            IdleStateEvent event = (IdleStateEvent)evt;
            String eventType = null;
            switch (event.state()){
                case READER_IDLE:
                    eventType="读空闲";
                    break;
                case WRITER_IDLE:
                    eventType="写空闲";
                    break;
                case ALL_IDLE:
                    eventType="读写空闲";
                    break;
            }
            System.out.println(ctx.channel().remoteAddress()+"超时时间"+eventType);
        }

    }
}

MyClient

package com.kkagr.netty.fourExample;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

public class MyClient {
    public static void main(String[] args) throws Exception{
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class)
                    .handler(new MyClientInitailizer());
            Channel channel = bootstrap.connect("localhost",8899).channel();
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            for(;;){
                channel.writeAndFlush(br.readLine()+"\r\n");
            }
        }finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

MyClientInitailizer

package com.kkagr.netty.fourExample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class MyClientInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096,Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        pipeline.addLast(new MyClientHandler());
    }
}

MyClientHandler

package com.kkagr.netty.fourExample;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class MyClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }
}

启动后效果如下
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案例五：netty实现客户端与服务端长连接
MyServer

package com.kkagr.netty.fifthExample;

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;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public class MyServer {
    public static void main(String[] args) throws Exception{
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workGroup).channel(NioServerSocketChannel.class).
                    handler(new LoggingHandler(LogLevel.INFO)).
                    childHandler(new MyServerInitailizer());
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
}

MyServerInitailizer

package com.kkagr.netty.fifthExample;

import java.util.concurrent.TimeUnit;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.stream.ChunkedWriteHandler;
import io.netty.handler.timeout.IdleStateHandler;

public class MyServerInitailizer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new HttpServerCodec());
        pipeline.addLast(new ChunkedWriteHandler());
        pipeline.addLast(new HttpObjectAggregator(8192));
        pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
        pipeline.addLast(new TextWebSocketFrameHandler());
    }
}

TextWebSocketFrameHandler

package com.kkagr.netty.fifthExample;

import java.time.LocalDateTime;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;

public class TextWebSocketFrameHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
        System.out.println("收到消息"+msg.text());
        ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器时间"+ LocalDateTime.now()));
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        System.out.println("handlerAdded"+ctx.channel().id().asLongText());
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        System.out.println("handlerRemoved"+ctx.channel().id().asLongText());
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        System.out.println("异常发生");
        ctx.close();
    }
}

在这里插入图片描述
test.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>websocket客户端</title>
</head>
<body>
<script type="text/javascript">
    var socket;
    if(window.WebSocket){
        socket = new WebSocket("ws://localhost:8899/ws");
        socket.onmessage = function (ev) {
            var ta = document.getElementById("responseText");
            ta.value=ta.value+"\n"+ev.data;
        }
        socket.onopen = function (ev) {
            var ta = document.getElementById("responseText");
            ta.value="连接开启！";
        }
        socket.onclose = function (ev) {
            var ta = document.getElementById("responseText");
            ta.value=ta.value+"\n"+"连接关闭";
        }

    }else{
        alert("浏览器不支持websocket");
    }

    function send(message) {
        if(!window.WebSocket){
            return;
        }
        if(socket.readyState == WebSocket.OPEN){
            socket.send(message);
        } else{
            alert("连接未开启");
        }
    }

</script>

<form onsubmit="return false">
    <textarea name="message" style="width: 400px;height: 200px"></textarea>
    <input type="button" value="发消息" onclick="send(this.form.message.value)">
    <h3>服务器输出：</h3>
    <textarea id="responseText" style="width: 400px;height: 200px"></textarea>
    <input type="button" onclick="javascript:document.getElementById('responseText').value=''" value="清空消息">
</form>

</body>
</html>

在这里插入图片描述
展示的到结果
在这里插入图片描述

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