《精通并发与Netty》学习笔记（02

上节我们介绍了开发netty项目所必需的开发环境及工具的使用，这节我们来写第一个netty项目

开发步骤

第一步：打开https://search.maven.org 找到netty依赖库

第二步：打开上节创建的项目，修改build.gradle文件如下图：

第三步：新建类com.ssy.netty.MyServer.class

package com.ssy.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;

/**
 * netty作为长连接的服务器基于websoket，实现客户端与服务器端长连接。
 */
public class MyServer {
    public static void main(String[] args) {
        //负责接收客户端连接
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        //处理连接
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup,workerGroup) // 绑定线程池
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ServerInitializer());

            //绑定端口号
            ChannelFuture channelFuture = serverBootstrap.bind(8888).sync();
            channelFuture.channel().closeFuture().sync();
        } catch (Exception e) {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

View Code

第四步：新建ServerInitializer类

package com.ssy.netty;

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

/**
 * 绑定客户端连接时候触发操作
 */
public class ServerInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        //负载http 请求编码解码
        pipeline.addLast("httpServerCodec",new HttpServerCodec());
        //实际处理请求
        pipeline.addLast("httpServerHandler",new HttpServerHandler());
    }
}

第五步：

package com.ssy.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;

/**
 * 给客户端返回字符串信息"hello world"
 */
public class HttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {
    /**
     * 该方法用于接收从客户端接收的信息
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
        if(msg instanceof HttpRequest){
            //设置返回内容,ByteBuf是一个引用计数对象实现ReferenceCounted，他就是在有对象引用的时候计数+1，无的时候计数-1，当为0对象释放内存
            ByteBuf content = Unpooled.copiedBuffer("hello world", CharsetUtil.UTF_8);
            //创建响应
            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());

            ctx.writeAndFlush(response);
        }

    }
}