看了好几天的netty实战,慢慢摸索,虽然还没有摸着很多门道,但今天还是把之前想加入到项目里的

一些想法实现了,算是有点信心了吧(讲真netty对初学者还真的不是很友好......)

 

首先,当然是在SpringBoot项目里添加netty的依赖了,注意不要用netty5的依赖,因为已经废弃了

             
                 
      
       io.netty
                  
      
       netty-all
                  
      
       4.1.32.Final
              
     

　　

将端口和IP写入application.yml文件里,我这里是我云服务器的内网IP,如果是本机测试,用127.0.0.1就ok

netty:  port: 7000  url: 172.16.0.7

　　

在这之后,开始写netty的服务器,这里服务端的逻辑就是将客户端发来的信息返回回去

因为采用依赖注入的方法实例化netty,所以加上@Component注解

1 package com.safelocate.app.nettyServer; 2  3 import io.netty.bootstrap.ServerBootstrap; 4 import io.netty.channel.*; 5 import io.netty.channel.nio.NioEventLoopGroup; 6 import io.netty.channel.socket.nio.NioServerSocketChannel; 7 import org.apache.log4j.Logger; 8 import org.springframework.stereotype.Component; 9 10 import java.net.InetSocketAddress;11 12 @Component13 public class NettyServer {14     //logger15     private static final Logger logger  = Logger.getLogger(NettyServer.class);16     public void start(InetSocketAddress address){17         EventLoopGroup bossGroup = new NioEventLoopGroup(1);18         EventLoopGroup workerGroup = new NioEventLoopGroup();19         try {20             ServerBootstrap bootstrap = new ServerBootstrap()21                     .group(bossGroup,workerGroup)22                     .channel(NioServerSocketChannel.class)23                     .localAddress(address)24                     .childHandler(new ServerChannelInitializer())25                     .option(ChannelOption.SO_BACKLOG, 128)26                     .childOption(ChannelOption.SO_KEEPALIVE, true);27             // 绑定端口，开始接收进来的连接28             ChannelFuture future = bootstrap.bind(address).sync();29             logger.info("Server start listen at " + address.getPort());30             future.channel().closeFuture().sync();31         } catch (Exception e) {32             e.printStackTrace();33             bossGroup.shutdownGracefully();34             workerGroup.shutdownGracefully();35         }36     }37 38 }

 

当然,这里的ServerChannelInitializer是我自己定义的类,这个类是继承ChannelInitializer<SocketChannel>的,里面设置出站和入站的编码器和解码器

package com.safelocate.app.nettyServer;import io.netty.channel.ChannelInitializer;import io.netty.channel.socket.SocketChannel;import io.netty.handler.codec.string.StringDecoder;import io.netty.handler.codec.string.StringEncoder;import io.netty.util.CharsetUtil;public class ServerChannelInitializer extends ChannelInitializer
      
        {    @Override    protected void initChannel(SocketChannel channel) throws Exception {        channel.pipeline().addLast("decoder",new StringDecoder(CharsetUtil.UTF_8));        channel.pipeline().addLast("encoder",new StringEncoder(CharsetUtil.UTF_8));        channel.pipeline().addLast(new ServerHandler());    }}
      

最好注意被别decoder和encoder写成了一样的,不然会出问题(我之前就是不小心都写成了StringDecoder...)

在这之后就是设置ServerHandler来处理一些简单的逻辑了

package com.safelocate.app.nettyServer;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;import io.netty.channel.SimpleChannelInboundHandler;import java.io.IOException;import java.io.OutputStream;import java.io.PrintWriter;import java.net.InetAddress;import java.net.Socket;public class ServerHandler extends ChannelInboundHandlerAdapter {    @Override    public void channelActive(ChannelHandlerContext ctx) {        System.out.println("channelActive----->");    }    @Override    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {        System.out.println("server channelRead......");        System.out.println(ctx.channel().remoteAddress()+"----->Server :"+ msg.toString());        //将客户端的信息直接返回写入ctx        ctx.write("server say :"+msg);        //刷新缓存区        ctx.flush();    }    @Override    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {        cause.printStackTrace();        ctx.close();    }}

准备工作到这里,现在要做到就是去启动这个程序

将AppApplication实现CommandLineRunner这个接口,这个接口可以用来再启动SpringBoot时同时启动其他功能,比如配置,数据库连接等等

然后重写run方法,在run方法里启动netty服务器,Server类用@AutoWired直接实例化

package com.safelocate.app;import com.safelocate.app.nettyServer.NettyServer;import io.netty.channel.ChannelFuture;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Value;import org.springframework.boot.CommandLineRunner;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import java.net.InetAddress;import java.net.InetSocketAddress;@SpringBootApplicationpublic class AppApplication implements CommandLineRunner {    @Value("${netty.port}")    private int port;    @Value("${netty.url}")    private String url;    @Autowired    private NettyServer server;    public static void main(String[] args) {        SpringApplication.run(AppApplication.class, args);    }    @Override    public void run(String... args) throws Exception {        InetSocketAddress address = new InetSocketAddress(url,port);        System.out.println("run  .... . ... "+url);        server.start(address);    }}

ok,到这里服务端已经写完,本地我也已经测试完,现在需要打包部署服务器,当然这个程序只为练手...

控制台输入mvn clean package -D skipTests 然后将jar包上传服务器,在这之后,需要在腾讯云/阿里云那边配置好安全组,将之前yml文件里设定的端口的入站

规则设置好,不然访问会被拒绝

之后java -jar命令运行,如果需保持后台一直运行 就用nohup命令,可以看到程序已经跑起来了,等待客户端连接交互

 

之后就是写客户端了,客户端其实是依葫芦画瓢,跟上面类似

Handler

package client;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;public class ClientHandler extends ChannelInboundHandlerAdapter {    @Override    public void channelActive(ChannelHandlerContext ctx) {        System.out.println("ClientHandler Active");    }    @Override    public void channelRead(ChannelHandlerContext ctx, Object msg) {        System.out.println("--------");        System.out.println("ClientHandler read Message:"+msg);    }    @Override    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {        cause.printStackTrace();        ctx.close();    }}

ChannelInitializer

package client;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelPipeline;import io.netty.channel.socket.SocketChannel;import io.netty.handler.codec.string.StringDecoder;import io.netty.handler.codec.string.StringEncoder;import io.netty.util.CharsetUtil;public class ClientChannelInitializer extends ChannelInitializer
      
        {    protected void initChannel(SocketChannel channel) throws Exception {        ChannelPipeline p = channel.pipeline();        p.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));        p.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));        p.addLast(new ClientHandler());    }}
      

主函数所在类,即客户端

package client;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.codec.string.StringDecoder;import io.netty.handler.codec.string.StringEncoder;public class Client {    static final String HOST = System.getProperty("host", "服务器的IP地址");    static final int PORT = Integer.parseInt(System.getProperty("port", "7000"));    static final int SIZE = Integer.parseInt(System.getProperty("size", "256"));    public static void main(String[] args) throws Exception {        sendMessage("hhhh");    }    public static void sendMessage(String content) throws InterruptedException{        // Configure the client.        EventLoopGroup group = new NioEventLoopGroup();        try {            Bootstrap b = new Bootstrap();            b.group(group)                    .channel(NioSocketChannel.class)                    .option(ChannelOption.TCP_NODELAY, true)                    .handler(new ChannelInitializer
      
       () {                        @Override                        public void initChannel(SocketChannel ch) throws Exception {                            ChannelPipeline p = ch.pipeline();                            p.addLast("decoder", new StringDecoder());                            p.addLast("encoder", new StringEncoder());                            p.addLast(new ClientHandler());                        }                    });            ChannelFuture future = b.connect(HOST, PORT).sync();            future.channel().writeAndFlush(content);            future.channel().closeFuture().sync();        } finally {            group.shutdownGracefully();        }    }}
      

 

启动客户端,这里就是简单发送一条"hhhh",可以看到客户端已经收到服务器发来的信息

然后再看服务端,也有相应的信息打印

 

推荐一个挺好的学netty的博客,https://blog.csdn.net/linuu/article/details/51306480,搭配netty实战这本书一起学习效果很好

 

实战：根据上面完成一个简（la）单（ji）的聊天室应用（无界面，基于CMD）

这里服务端可以单独分出来可以单独作为一个工程打包为jar，万万没必要Springboot，但这里懒得改了，就还是当后台用吧hhh

首先，服务端需要展示的就是每个人所发出来的信息，和对上线人数下线人数进行实时的更新，之前更新是利用一个静态变量,

但是这样硬核了一点,这里正好要用到群发的功能,所以我们需要一个list来存放Channel,然后将这个list的size作为在线人数就好了

群发就遍历这个数组,然后writeAndFlush

package com.safelocate.app.nettyServer;import io.netty.channel.*;import io.netty.channel.group.ChannelGroup;import io.netty.channel.group.DefaultChannelGroup;import io.netty.util.concurrent.GlobalEventExecutor;public class ServerHandler extends ChannelInboundHandlerAdapter {    private static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);    @Override    public void handlerAdded(ChannelHandlerContext ctx) throws Exception{        channels.add(ctx.channel());//加入ChannelGroup        System.out.println(ctx.channel().id()+" come into the chattingroom,"+"Online: "+channels.size());    }    @Override    public void handlerRemoved(ChannelHandlerContext context){        System.out.println(context.channel().id()+" left the chattingroom,"+"Online: "+channels.size());    }    @Override    public void channelActive(ChannelHandlerContext ctx) {    }    @Override    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {        //打印消息然后群发        System.out.println(msg.toString());        for (Channel channel:channels){            channel.writeAndFlush(msg.toString());        }    }    @Override    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {        System.out.println(ctx.channel().id()+" occurred into error,"+"Online: "+channels.size());        ctx.close();    }}

照样，打包成jar，java -jar命令运行就行，哦对由于这里是本地测试，所以yml文件中的IP应该换成127.0.0.1

接下来是客户端，首先明确的就是用户需要输入信息，所以肯定要用到输入函数，比如Scanner，另外，服务端需要知道每一个人的身份，这里

简单的用昵称来代替，在发送的时候将名字也一并发过去，这样就能简单分辨是谁发的信息（其实这样做主要是因为没来得及写数据库升级复杂一点的逻辑）

所以，在之前发信息的函数里稍微处理一下就行，即增加信息输入模块

public static void sendMessage() throws InterruptedException{        // Configure the client.        EventLoopGroup group = new NioEventLoopGroup();        try {            Bootstrap b = new Bootstrap();            b.group(group)                    .channel(NioSocketChannel.class)                    .option(ChannelOption.TCP_NODELAY, true)                    .handler(new ChannelInitializer
      
       () {                        @Override                        public void initChannel(SocketChannel ch) throws Exception {                            ChannelPipeline p = ch.pipeline();                            p.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));                            p.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));                            p.addLast(new ClientHandler());                        }                    });            ChannelFuture future = b.connect(HOST, PORT).sync();            Scanner sca=new Scanner(System.in);            while (true){                String str=sca.nextLine();//输入的内容                if (str.equals("exit"))                    break;//如果是exit则退出                future.channel().writeAndFlush(name+"-: "+str);//将名字和信息内容一起发过去            }            future.channel().closeFuture().sync();        } finally {            group.shutdownGracefully();        }    }
      

之后把IP改成127.0.0.1就行，打包的时候，需要在pom文件中添加打包插件，特别注意的是要制定mainClass，不然运行时会报“没有主清单属性”

这里贴上插件配置，这个插件其实对于所有Java程序都适用，因为他会把依赖全带上

                  
                      
       
        org.apache.maven.plugins
                       
       
        maven-compiler-plugin
                       
                           
        1.8                    
        
         1.8
                            
        
         UTF-8
                        
                   
                  
                      
       
        org.apache.maven.plugins
                       
       
        maven-jar-plugin
                       
                           
                                
                                     
          
           true
                                      
          
           lib/
                                      
          
           client.Client
                                  
                             
                        
                   
                  
                      
       
        org.apache.maven.plugins
                       
       
        maven-dependency-plugin
                       
                           
                                
         
          copy
                                 
         
          install
                                 
                                     
          
           copy-dependencies
                                  
                                 
                                     
          
           ${project.build.directory}/lib
                                  
                             
                        
                   
      

打包后之后就是运行了，效果大概是这样.。。。。。。

哈哈哈哈有时间再完善一下