Netty（2） - HelloWorld-白红宇

Netty（2） - HelloWorld

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发布时间：2019-06-14

本文共 4556 字，大约阅读时间需要 15 分钟。

Netty：作用场景。

1）Netty可以基于socket实现远程过程调用（RPC）。

2）Netty可以基于WebSocket实现长连接。

3）Netty可以实现Http的服务器，类似于Jetty，Tomcat等Servlet容器。

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Netty充当Http服务器，我们通过浏览器去访问服务器的资源，服务器端处理完之后给我们返回响应-----Helloworld。

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1）定义一个Server

1 package com.foreign.netty.helloworld; 2  3 import io.netty.bootstrap.ServerBootstrap; 4 import io.netty.channel.ChannelFuture; 5 import io.netty.channel.EventLoopGroup; 6 import io.netty.channel.nio.NioEventLoopGroup; 7 import io.netty.channel.socket.nio.NioServerSocketChannel; 8 9 /** 10 * Created with IDEA 11 * author:foreign 12 * Date:2018/12/25 13 * Time:23:21 14 */ 15 public class TestServer { 16 public static void main(String[] args) throws InterruptedException { 17 /** 18 * 两个事件循环组(死循环) boos接受连接并发送给worker 19 */ 20 EventLoopGroup bossLooper = new NioEventLoopGroup(); 21 EventLoopGroup workerLooper = new NioEventLoopGroup(); 22 23 try { 24 /** 25 * ServerBootstrap 服务端启动 26 * NioServerSocketChannel 通道（反射） 27 */ 28 ServerBootstrap serverBootstrap = new ServerBootstrap(); 29 serverBootstrap.group(bossLooper, workerLooper).channel(NioServerSocketChannel.class).childHandler(new TestServerInitializer()); 30 31 ChannelFuture channelFuture = serverBootstrap.bind(8899).sync(); 32  channelFuture.channel().closeFuture().sync(); 33 } finally { 34  bossLooper.shutdownGracefully(); 35  workerLooper.shutdownGracefully(); 36  } 37  } 38 }

2）定义一个Initializer

1 package com.foreign.netty.helloworld; 2  3 import io.netty.channel.ChannelInitializer; 4 import io.netty.channel.ChannelPipeline; 5 import io.netty.channel.socket.SocketChannel; 6 import io.netty.handler.codec.http.HttpServerCodec; 7  8 /** 9  * Created with IDEA10  * author:foreign11  * Date:2018/12/2512  * Time:23:3213  */14 public class TestServerInitializer extends ChannelInitializer
     
       { 15 16 /** 17 * 子处理器， channel被注册好，会被自动创建 18 * @param ch 19 * @throws Exception 20 */ 21  @Override 22 protected void initChannel(SocketChannel ch) throws Exception { 23 ChannelPipeline pipeline = ch.pipeline(); 24 //编解码 25 pipeline.addLast("httpServerCodec",new HttpServerCodec()); 26 //自己定义的handler 27 pipeline.addLast("testHttpServerHandler",new TestHttpServerHandler()); 28 29  } 30 }

3）定义一个Handler

1 package com.foreign.netty.helloworld; 2  3 import io.netty.buffer.ByteBuf; 4 import io.netty.buffer.Unpooled; 5 import io.netty.channel.ChannelHandlerContext; 6 import io.netty.channel.SimpleChannelInboundHandler; 7 import io.netty.handler.codec.http.*; 8 import io.netty.util.CharsetUtil; 9 10 import java.net.URI;11 12 /**13  * Created with IDEA14  * author:foreign15  * Date:2018/12/2516  * Time:23:3417  */18 public class TestHttpServerHandler extends SimpleChannelInboundHandler
     
       {19     /**20      * 把结果返回给客户端（回调）21      */22     @Override23     protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {24         if (msg instanceof HttpRequest) {25 26             HttpRequest httpRequest = (HttpRequest) msg;27 28             //获取请求的方法类型29             System.out.println(httpRequest.method().name());30 31             URI uri = new URI(httpRequest.uri());32             if("/favicon.io".equals(uri)) {33                 System.out.println("请求了favicon.io 图标");34                 return;35             }36 37             ByteBuf content = Unpooled.copiedBuffer("Hello Netty", CharsetUtil.UTF_8);38             FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, content);39             response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain");40             response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());41 42             ctx.writeAndFlush(response);43 44             ctx.channel().close();45         }46     }47 }

4）gradle的配置

plugins {    id 'java'}group 'com.foreign'version '1.0-SNAPSHOT'apply plugin: 'java'sourceCompatibility = 1.8targetCompatibility = 1.8repositories {    mavenCentral()}dependencies {    implementation 'io.netty:netty-all:4.1.10.Final'    testCompile (            "junit:junit:4.11"    )}

5）运行结果：运行server，并访问该地址。