SpringBoot整合Netty

總體來說只需要三個步驟，下面詳細介紹

第一步 創建SpringBoot工程snetty

第二步 創建子模塊也就是ModuleClient,Server,均為SpringBoot工程
第三步 將服務器端和客戶端的代碼分別打成Jar包，運行Jar包。因為Netty需要客戶端與服務器端兩個端口才能看到效果，但是IDE的console只有一個窗口，所以需要將兩個端口代碼分別打成Jar包,這樣再運行的話，就有兩個窗口了。

先說一下遇到的問題,具體代碼在下邊。

打包運行

因為我運行Jar包使用的是mvn exec:java這個命令，是將主函數main的參數構建在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>

也就是說當我用mvn clean package這個命令將服務器端的代碼打成Jar包之后，再運行mvn exec:java命令，此時服務器端就啟動了。

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

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

這里放的是主函數的參數。

獲取父級pom.xml的信息

${echo-server.port}這個值是從父級pom.xml中的properties中獲取的，很關鍵的就是，在子模塊Server的pom.xml中的<parent>標簽中要這么寫才能獲得父級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>

父級中的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>

並且父級中的<packaging>標簽要改成pom形式

<packaging>pom</packaging>

具體代碼

引入依賴

<!--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>

服務器端和客戶端都只需要兩部分代碼，一個是處理器程序，一個是引導程序。

服務器端的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();
    }
}

服務器端的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();
        }
    }
}

客戶端的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> {

    //在到服務器的連接已經建立之后將被調用
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.copiedBuffer("Netty rocks!",
                CharsetUtil.UTF_8));
    }
    //當從服務器接收到一條消息時被調用
    @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();
    }
}

客戶端的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();
    }
}