SpringBoot整合Netty

总体来说只需要三个步骤，下面详细介绍

第一步 创建SpringBoot工程snetty

第二步 创建子模块也就是ModuleClient,Server,均为SpringBoot工程
第三步 将服务器端和客户端的代码分别打成Jar包，运行Jar包。因为Netty需要客户端与服务器端两个端口才能看到效果，但是IDE的console只有一个窗口，所以需要将两个端口代码分别打成Jar包,这样再运行的话，就有两个窗口了。

先说一下遇到的问题,具体代码在下边。

打包运行

因为我运行Jar包使用的是mvn exec:java这个命令，是将主函数main的参数构建在pom.xml文件中。

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.2.1</version>
            <executions>
                <execution>
                    <id>run-server</id>
                    <goals>
                        <goal>java</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <mainClass>com.bihang.server.server2.EchoServer</mainClass>
                <arguments>
                    <argument>${echo-server.port}</argument>
                </arguments>
            </configuration>
        </plugin>
    </plugins>
</build>

也就是说当我用mvn clean package这个命令将服务器端的代码打成Jar包之后，再运行mvn exec:java命令，此时服务器端就启动了。

<mainClass>com.bihang.server.server2.EchoServer</mainClass>这里放的就是主函数。

<arguments>
    <argument>${echo-server.port}</argument>
</arguments>

这里放的是主函数的参数。

获取父级pom.xml的信息

${echo-server.port}这个值是从父级pom.xml中的properties中获取的，很关键的就是，在子模块Server的pom.xml中的<parent>标签中要这么写才能获得父级pom.xml中的信息。

<parent>
    <groupId>com.bihang</groupId>
    <artifactId>snetty</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <relativePath>../pom.xml</relativePath> <!-- lookup parent from repository -->
</parent>

父级中的properties:

<properties>
    <java.version>1.8</java.version>
    <echo-server.hostname>127.0.0.1</echo-server.hostname>
    <echo-server.port>8888</echo-server.port>
</properties>

并且父级中的<packaging>标签要改成pom形式

<packaging>pom</packaging>

具体代码

引入依赖

<!--Netty-->
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.0.36.Final</version>
</dependency>
<!--Netty END-->
<!-- 日志文件管理包 -->
<!-- log start -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

服务器端和客户端都只需要两部分代码，一个是处理器程序，一个是引导程序。

服务器端的EchoServerHandler

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

@ChannelHandler.Sharable
public class EchoServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf in = (ByteBuf) msg;
        System.out.println(
                "Server received: " + in.toString(CharsetUtil.UTF_8));
        ctx.write(in);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
                .addListener(ChannelFutureListener.CLOSE);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

服务器端的EchoServer

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

import java.net.InetSocketAddress;

public class EchoServer {
    private final int port;

    public EchoServer(int port) {
        this.port = port;
    }

    public static void main(String[] args) throws Exception {
        if (args.length != 1) {
            System.err.println(
                    "Usage: " + EchoServer.class.getSimpleName() +
                            " <port>");
        }
        int port = Integer.parseInt(args[0]);
        new EchoServer(port).start();
    }

    public void start() throws Exception {
        final EchoServerHandler serverHandler = new EchoServerHandler();
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(group)
                    .channel(NioServerSocketChannel.class)
                    .localAddress(new InetSocketAddress(port))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(serverHandler);
                        }
                    });
            ChannelFuture f = b.bind().sync();
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully().sync();
        }
    }
}

客户端的EchoClientHandler

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;

public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {

    //在到服务器的连接已经建立之后将被调用
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("Netty rocks!",
                CharsetUtil.UTF_8));
    }
    //当从服务器接收到一条消息时被调用
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, ByteBuf in) throws Exception {
        System.out.println(
                "Client received: " + in.toString(CharsetUtil.UTF_8));
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

客户端的EchoClient

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.net.InetSocketAddress;

public class EchoClient {
    private final String host;
    private final int port;

    public EchoClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void start() throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .remoteAddress(new InetSocketAddress(host, port))
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch)
                                throws Exception {
                            ch.pipeline().addLast(
                                    new EchoClientHandler());
                        }
                    });
            ChannelFuture f = b.connect().sync();
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args) throws Exception {
        if (args.length != 2) {
            System.err.println(
                    "Usage: " + EchoClient.class.getSimpleName() +
                            " <host> <port>");
            return;
        }
        String host = args[0];
        int port = Integer.parseInt(args[1]);
        new EchoClient(host, port).start();
    }
}