在Netty学习笔记(一) 实现DISCARD服务中，我们使用Netty和Python实现了简单的丢弃DISCARD服务，这篇，我们使用Netty实现服务端和客户端交互的需求。
前置工作
开发环境
- JDK8
- Netty版本:5.0.0.Alpha2
- 集成环境:IDEA
- 构建工具：Gradle
依赖
compile group: 'io.netty', name: 'netty-all', version: '5.0.0.Alpha2'
compile group: 'org.projectlombok', name: 'lombok', version: '1.18.0'
服务端
Netty服务器主要由两部分组成:
- 配置服务器功能，如线程、端口
- 实现服务器处理程序
服务端HandleAdapter
我们是首先实现服务端处理程序，实现Handle要求继承HandleAdapter,这里我们继承SimpleChannelInboundHandler<T>,下面是具体实现的代码信息,其每个函数的作用，我们只需要重写我们所需要的方法即可。
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
/**
* Netty 服务Handle
*
* @author tao
*/
@ChannelHandler.Sharable
public class EchoServiceHandle extends SimpleChannelInboundHandler<String> {
/**
* 接收到新的消息
* @param ctx
* @param msg
* @throws Exception
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// 打印接收到的消息
System.out.println("Netty服务端接收到消息 " + msg);
// 回复消息
ctx.channel().writeAndFlush("Send ----> 客户端" + ctx.channel().id() + "你好，我已经接收到你发送的消息");
}
/**
* 有新的连接加入
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("接入新的Channel,id = " + ctx.channel().id());
}
/**
* 服务端发生异常信息的时候
* @param ctx
* @param cause
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// 服务端发生异常
System.out.println("Netty 服务端发生异常 ,异常信息：" + cause);
ctx.close();
}
@Override
protected void messageReceived(ChannelHandlerContext ctx, String msg) {}
}
服务端启动
在服务端的EchoServiceHandle完成之后，我们需要配置服务器的参数信息，比如端口等
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import lombok.Data;
/**
* @author tao
*/
@Data
public class EchoService {
private int port;
public void start() throws Exception {
EventLoopGroup boosGroup = new NioEventLoopGroup();
EventLoopGroup workGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap
.group(boosGroup, workGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128)
.childHandler(
new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//字符串解码器
pipeline.addLast(new StringDecoder());
//字符串编码器
pipeline.addLast(new StringEncoder());
//服务端处理器
pipeline.addLast(new EchoServiceHandle());
}
});
ChannelFuture sync = bootstrap.bind(port).sync();
System.out.println("Netty Service start with " + port + "...");
sync.channel().closeFuture().sync();
} finally {
workGroup.shutdownGracefully();
boosGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
EchoService service = new EchoService();
service.setPort(8080);
service.start();
}
}
启动后，我们可以看到启动信息如下:
Netty Service start with 8080...
客户端
客户端和服务端类似,可以相互参考学习.
客户端HandleAdapter
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;
@ChannelHandler.Sharable
public class EchoClientHandle extends SimpleChannelInboundHandler<String> {
/**
* 连接创建成功的时候
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("channelActive");
//连接成功后向服务端发送问候消息
ctx.channel().writeAndFlush(Unpooled.copiedBuffer("你好，这里是Netty客户端", CharsetUtil.UTF_8));
}
/**
* 发生异常
* @param ctx
* @param cause
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
System.out.println("exceptionCaught");
cause.printStackTrace();
ctx.close();
}
/**
* 接收到服务端发过来的数据
* @param ctx
* @param msg
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
//打印接收到的数据信息
System.out.println("channelRead = " + msg);
}
@Override
protected void messageReceived(ChannelHandlerContext ctx, String msg) {}
}
客户端启动
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
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 io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import lombok.Data;
import lombok.experimental.Accessors;
import lombok.extern.slf4j.Slf4j;
import java.net.InetSocketAddress;
/** @author tao */
@Data
@Accessors(chain = true)
@Slf4j
public class EchoClient {
private int port;
private String host;
public void start() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap
.group(group)
.channel(NioSocketChannel.class)
.handler(
new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
// 字符串解码器
pipeline.addLast(new StringDecoder());
// 字符串编码器
pipeline.addLast(new StringEncoder());
pipeline.addLast(new EchoClientHandle());
}
});
ChannelFuture sync = bootstrap.connect(new InetSocketAddress(host, port)).sync();
sync.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
group.shutdownGracefully().sync();
}
}
public static void main(String[] args) throws Exception {
EchoClient client = new EchoClient();
client.setHost("127.0.0.1").setPort(8080);
client.start();
}
}
效果
服务端效果
Netty Service start with 8080...
接入新的Channel,id = c0d4f037
Netty服务端接收到消息 你好，这里是Netty客户端
客户端效果
channelActive
channelRead = Send ----> 客户端c0d4f037你好，我已经接收到你发送的消息