netty框架

在网络编程领域，Netty是Java的一个优秀的框架，他将java的复杂和难以使用的关于OIO和NIO的一些框架
进行了封装，使其隐藏在易用的api后面。总之，如果你想编写高性能的网络服务，那么使用Netty就没错了。
目前各个大公司比如google,facebook等公司都在使用Netty框架，很多项目比如dubbo和Elasticsearch等就使用了Netty.

netty和springboot的整合

之前一直使用的都是springboot框架，习惯了spring的容器，于是就想着把netty也放到容器中以便于方便使用。
这次先用个demo先实现下，以后有更好的方式的时候再来更新。
首先是 pom.xml 文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>liqiangz</groupId>
    <artifactId>netty-test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId> <!-- Use 'netty-all' for 4.0 or above -->
            <version>4.1.32.Final</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-log4j</artifactId>
            <version>1.3.8.RELEASE</version>
        </dependency>
    </dependencies>
    <repositories>
        <repository>
            <id>aliyunmaven</id>
            <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
        </repository>
    </repositories>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

然后是 启动main方法
在这里实现了CommandLineRunner接口，并重写了run方法，以便在springboot启动后就立即启动netty服务。

package io.liqiangz.server;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * The type Netty application.
 * @author liqiangz
 */
@SpringBootApplication
public class NettyApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(NettyApplication.class, args);
    }

    @Override
    public void run(String... strings) throws Exception {
        EchoServer echoServer = new EchoServer(8080);
        echoServer.start();
    }
}

接下来就是netty服务启动引导类,很简单的一个echo服务

package io.liqiangz.server;

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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetSocketAddress;

/**
 * @author     ：liqiangz.
 * @date       ：Created in 21:03 2018/12/15
 */
public class EchoServer {
    private final int port;
    private Logger log = LoggerFactory.getLogger(this.getClass());
    public EchoServer(int port) {
        this.port = port;
    }

    public void start() throws Exception {
        final EchoServerHandler serverHandler = new EchoServerHandler();
        log.info("启动服务");
        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();
        }
    }
}

serverHandler类

package io.liqiangz.server;

import io.netty.buffer.ByteBuf;
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;

/**
 * @author     ：liqiang.
 * @date       ：Created in 21:04 2018/12/15
 */
@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(ChannelFutureListener.CLOSE);
    }

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

}