SpringBoot集成netty实现客户端服务端交互和做一个简单的IM

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

        <!--netty-->
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.32.Final</version>
        </dependency>

　　

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

package com.safelocate.app.nettyServer;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import org.apache.log4j.Logger;
import org.springframework.stereotype.Component;

import java.net.InetSocketAddress;

@Component
public class NettyServer {
    //logger
    private static final Logger logger  = Logger.getLogger(NettyServer.class);
    public void start(InetSocketAddress address){
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap = new ServerBootstrap()
                    .group(bossGroup,workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .localAddress(address)
                    .childHandler(new ServerChannelInitializer())
                    .option(ChannelOption.SO_BACKLOG, 128)
                    .childOption(ChannelOption.SO_KEEPALIVE, true);
            // 绑定端口，开始接收进来的连接
            ChannelFuture future = bootstrap.bind(address).sync();
            logger.info("Server start listen at " + address.getPort());
            future.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

}

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<SocketChannel> {
    @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;
@SpringBootApplication
public 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<SocketChannel> {
    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<SocketChannel>() {
                        @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<SocketChannel>() {
                        @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

<!-- java编译插件 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>lib/</classpathPrefix>
                            <mainClass>client.Client</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <executions>
                    <execution>
                        <id>copy</id>
                        <phase>install</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.directory}/lib</outputDirectory>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

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