构建异步高并发服务器：Netty与Spring Boot的完美结合 - ToB企服应用市场:ToB评测及商务社交产业平台

<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.76.Final</version>
</dependency>

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@Slf4j
public class NettyServer {
private final static int PORT = 9012;
public static void main(String[] args) throws InterruptedException {
/**
* 包含childGroup，childHandler，config，继承的父类AbstractBootstrap包括了parentGroup
* */
ServerBootstrap bootstrap = new ServerBootstrap();
/**
* EventLoopGroup用于处理所有ServerChannel和Channel的所有事件和IO
* */
EventLoopGroup parentGroup = new NioEventLoopGroup();
EventLoopGroup childGroup = new NioEventLoopGroup();
try {
/**
* 绑定两个事件组
* */
bootstrap.group(parentGroup, childGroup)
/**
* 初始化socket，定义tcp连接的实例
* 内部调用ReflectiveChannelFactory实现对NioServerSocketChannel实例化
* channelFactory是在AbstractBootstrap，也就是bootstrap的父类
* */
.channel(NioServerSocketChannel.class)
/**
* 添加处理器
* ChannelInitializer包括了Set<ChannelHandlerContext> initMap
*
* 这里比较有趣的事情就是使用被注册的channel去初始化其他的channel，
* 等初始化结束后移除该channel
* 所以SocketChannel是一个工具，
*
* 在bind绑定端口的时候，进行初始化和注册initAndRegister，
* 通过channel = channelFactory.newChannel()得到初始化channel
* init(channel)真正开始初始化，
* p = channel.pipeline()得到ChannelPipeline，
* p.addLast开始添加
* ch.eventLoop().execute将childHandler赋值并开启一个任务setAutoRead
* 所以最后在监听读取的时候将会按照下面添加的channel进行读取
*
* ChannelInitializer继承了ChannelInboundHandlerAdapter
* 间接继承ChannelHandlerAdapter，ChannelInboundHandler，
* */
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
/**
* ByteBuf和String之间的转换
*
* Decoders解密
* pipeline.addLast("frameDecoder", new {@link LineBasedFrameDecoder}(80))
* pipeline.addLast("stringDecoder", new {@link StringDecoder}(CharsetUtil.UTF_8))
*
* Encoder加密
* pipeline.addLast("stringEncoder", new {@link StringEncoder}(CharsetUtil.UTF_8))
*
* 使用上面的加密解密后就可以直接读取字符串
* void channelRead({@link ChannelHandlerContext} ctx, String msg) {
* ch.write("Did you say '" + msg + "'?\n")
* }
*
* */
pipeline.addLast(new StringDecoder());
pipeline.addLast(new StringEncoder());
//自定义处理器
pipeline.addLast(new ServerHandler1());
}
});
ChannelFuture future = bootstrap.bind(PORT).sync();
log.info("服务器已启动");
future.channel().closeFuture().sync();
} finally {
parentGroup.shutdownGracefully();
childGroup.shutdownGracefully();
}
}
}

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@Slf4j
public class ServerHandler1 extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
log.info("Client Address ====== {}，读取的信息：{}", ctx.channel().remoteAddress(),msg);
ctx.channel().writeAndFlush("服务端writeAndFlush：我是服务端");
ctx.fireChannelActive();
//睡眠
TimeUnit.MILLISECONDS.sleep(500);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
//打印异常
cause.printStackTrace();
//关闭Channel连接，并通知ChannelFuture，通常是出现异常或者是完成了操作
ctx.close();
}
}

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@Slf4j
public class NettyClient {
private final static int PORT = 9012;
private final static String IP = "localhost";
public static void main(String[] args) throws InterruptedException {
/**
* 服务端是ServerBootstrap，客户端是Bootstrap
* Bootstrap引导channel连接，UDP连接用bind方法，TCP连接用connect方法
* */
Bootstrap bootstrap = new Bootstrap();
/**
* 服务端是EventLoopGroup，客户端是NioEventLoopGroup
* 这里创建默认0个线程，一个线程工厂，一个选择器提供者
* */
NioEventLoopGroup eventLoopGroup = new NioEventLoopGroup();
try {
bootstrap.group(eventLoopGroup)
/**
* 初始化socket，定义tcp连接的实例
* */
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
/**
* 进行字符串的转换
* */
pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
/**
* 自定义处理器
* */
pipeline.addLast(new ClientHandler1());
}
});
ChannelFuture future = bootstrap.connect(IP, PORT).sync();
log.info("客户端访问");
future.channel().closeFuture().sync();
} finally {
eventLoopGroup.shutdownGracefully();
}
}
}

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@Slf4j
public class ClientHandler1 extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
log.info("客户端读取的信息：{}", msg);
ctx.channel().writeAndFlush("客户端writeAndFlush：我是客户端");
TimeUnit.MILLISECONDS.sleep(5000);
}
/**
* 当事件到达pipeline时候触发
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
ctx.channel().writeAndFlush("客户端：开始聊天");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
//关闭Channel连接
ctx.close();
}
}

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Client Address ====== /127.0.0.1:63740，读取的信息：客户端：开始聊天
Client Address ====== /127.0.0.1:63740，读取的信息：客户端writeAndFlush：我是客户端
Client Address ====== /127.0.0.1:63740，读取的信息：客户端writeAndFlush：我是客户端

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客户端读取的信息：服务端writeAndFlush：我是服务端
客户端读取的信息：服务端writeAndFlush：我是服务端

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