Netty（2） - HelloWorld

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 IDEA

10  * author:foreign

11  * Date:2018/12/25

12  * Time:23:32

13  */

14 public class TestServerInitializer extends ChannelInitializer<SocketChannel> {

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 IDEA

14  * author:foreign

15  * Date:2018/12/25

16  * Time:23:34

17  */

18 public class TestHttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {

19     /**

20      * 把结果返回给客户端（回调）

21      */

22     @Override

23     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 = 1.8

targetCompatibility = 1.8

repositories {

    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。

6）总结：

1）在TestServer类中，启动一个ServerBootStrap的服务器，里面有两个事件循环组，并且通childHandler关联处理器。

2）在TestServerInitializer中加载netty内置的handler和自己的handler。

3）在TestHttpServerHandler中返回数据到客户端。

7）项目代码：https://github.com/fk123456/Netty/

巴特西

Netty（2） - HelloWorld

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