maven导包
<dependency>
四个类：
package learn.io.netty;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
public class Server {
private int port;
public Server(int port) {
this.port = port;
}
public void run() {
EventLoopGroup bossGroup = new NioEventLoopGroup(); //用于处理服务器端接收客户端连接
EventLoopGroup workerGroup = new NioEventLoopGroup(); //进行网络通信（读写）
try {
ServerBootstrap bootstrap = new ServerBootstrap(); //辅助工具类，用于服务器通道的一系列配置
bootstrap.group(bossGroup, workerGroup) //绑定两个线程组
.channel(NioServerSocketChannel.class) //指定NIO的模式
.childHandler(new ChannelInitializer() { //配置具体的数据处理方式
protected void initChannel(SocketChannel socketChannel) throws Exception {
socketChannel.pipeline().addLast(new ServerHandler());
}
})
/**
* 对于ChannelOption.SO_BACKLOG的解释：
* 服务器端TCP内核维护有两个队列，我们称之为A、B队列。客户端向服务器端connect时，会发送带有SYN标志的包（第一次握手），服务器端
* 接收到客户端发送的SYN时，向客户端发送SYN ACK确认（第二次握手），此时TCP内核模块把客户端连接加入到A队列中，然后服务器接收到
* 客户端发送的ACK时（第三次握手），TCP内核模块把客户端连接从A队列移动到B队列，连接完成，应用程序的accept会返回。也就是说accept
* 从B队列中取出完成了三次握手的连接。
* A队列和B队列的长度之和就是backlog。当A、B队列的长度之和大于ChannelOption.SO_BACKLOG时，新的连接将会被TCP内核拒绝。
* 所以，如果backlog过小，可能会出现accept速度跟不上，A、B队列满了，导致新的客户端无法连接。要注意的是，backlog对程序支持的
* 连接数并无影响，backlog影响的只是还没有被accept取出的连接
*/
.option(ChannelOption.SO_BACKLOG, 128) //设置TCP缓冲区
.option(ChannelOption.SO_SNDBUF, 32 * 1024) //设置发送数据缓冲大小
.option(ChannelOption.SO_RCVBUF, 32 * 1024) //设置接受数据缓冲大小
.childOption(ChannelOption.SO_KEEPALIVE, true); //保持连接
ChannelFuture future = bootstrap.bind(port).sync();
future.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) {
new Server(8379).run();
}
}
package learn.io.netty;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class ServerHandler extends ChannelHandlerAdapter {
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
//do something msg
ByteBuf buf = (ByteBuf)msg;
byte[] data = new byte[buf.readableBytes()];
buf.readBytes(data);
String request = new String(data, "utf-8");
System.out.println("Server: " + request);
//写给客户端
String response = "我是反馈的信息";
ctx.writeAndFlush(Unpooled.copiedBuffer("888".getBytes()));
//.addListener(ChannelFutureListener.CLOSE);
}
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
package learn.io.netty;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
public class Client {
public static void main(String[] args) throws InterruptedException {
NioEventLoopGroup workerGroup = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(workerGroup)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer() {
protected void initChannel(SocketChannel socketChannel) throws Exception {
socketChannel.pipeline().addLast(new ClientHandler());
}
});
ChannelFuture future = bootstrap.connect("127.0.0.1", 8379).sync();
future.channel().writeAndFlush(Unpooled.copiedBuffer("777".getBytes()));
future.channel().closeFuture().sync();
workerGroup.shutdownGracefully();
}
}
package learn.io.netty;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;
public class ClientHandler extends ChannelHandlerAdapter {
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
ByteBuf buf = (ByteBuf) msg;
byte[] data = new byte[buf.readableBytes()];
buf.readBytes(data);
System.out.println("Client：" + new String(data).trim());
} finally {
ReferenceCountUtil.release(msg);
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}