目录
案例要求:
- 编写一个 Netty 群聊系统，实现服务器端和客户端之间的数据简单通讯
- 实现多人群聊
- 服务器端：可以监测用户上线，离线，并实现消息转发功能
- 客户端：可以发送消息给其它所有用户，同时可以接受其它用户发送的消息
思路：
基于SimpleChannelInboundHandler来编写服务器和客户端的Handler，前面说过，SimpleChannelInboundHandler能自动管理消息对象的引用计数，简化数据读取事件的处理。
使用SimpleChannelInboundHandler时需要指定泛型为String，并实现channelRead0方法，用于读取消息，那么就能自动管理消息对象的引用计数了。
服务端维护一个所有客户端连接的列表，当收到客户端消息时，在Handler里channelRead0方法里读取内容，并发送给出了当前客户端的其他客户端。
聊天室服务端编写
- 服务器Handler
java
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import java.util.ArrayList;
import java.util.List;
public class NettyChatServerHandler extends SimpleChannelInboundHandler<String> {
/**
* 通道集合，用于放置所有的连接对象的通道
*/
public static List<Channel> channelList = new ArrayList<>();
/**
* 通道就绪事件
*
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
Channel channel = ctx.channel();
//当有新的客户端连接的时候, 将通道放入集合
channelList.add(channel);
System.out.println("[Server]:" +
channel.remoteAddress().toString().substring(1) + "在线.");
}
/**
* 通道未就绪--channel下线
*
* @param ctx
* @throws Exception
*/
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
Channel channel = ctx.channel();
//当有客户端断开连接的时候,就移除对应的通道
channelList.remove(channel);
System.out.println("[Server]:" +
channel.remoteAddress().toString().substring(1) + "下线.");
}
/**
* 通道读取事件
*
* @param channelHandlerContext
* @param msg
* @throws Exception
*/
@Override
protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
//通过当前发送消息的通道, 获取当前发送的客户端连接
Channel curChannel = channelHandlerContext.channel();
//遍历所有的客户端连接通道
for (Channel channel : channelList) {
// 如果当前通道不是自己，才发发消息
if (channel != curChannel) {
channel.writeAndFlush("[" + channel.remoteAddress().toString().substring(1) + "]说:" + msg);
}
}
}
/**
* 异常处理事件
*
* @param ctx
* @param cause
* @throws Exception
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
Channel channel = ctx.channel();
//移除集合
channelList.remove(channel);
System.out.println("[Server]:" +
channel.remoteAddress().toString().substring(1) + "异常.");
}
}- 服务器代码
java
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;
/**
* 聊天室服务端
* @author test
*/
public class NettyChatServer {
//端口号
private int port;
public NettyChatServer(int port) {
this.port = port;
}
public void run() throws InterruptedException {
//1. 创建bossGroup线程组: 处理网络事件--连接事件
EventLoopGroup bossGroup = null;
//2. 创建workerGroup线程组: 处理网络事件--读写事件 2*处理器线程数
EventLoopGroup workerGroup = null;
try {
bossGroup = new NioEventLoopGroup(1);
workerGroup = new NioEventLoopGroup();
//3. 创建服务端启动助手
ServerBootstrap serverBootstrap = new ServerBootstrap();
//4. 设置bossGroup线程组和workerGroup线程组
serverBootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class) //5. 设置服务端通道实现为NIO
.option(ChannelOption.SO_BACKLOG, 128)//6. 参数设置
.childOption(ChannelOption.SO_KEEPALIVE, Boolean.TRUE)//6. 参数设置
.childHandler(new ChannelInitializer<SocketChannel>() { //7. 创建一个通道初始化对象
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//8. 向pipeline中添加自定义业务处理handler
//添加编解码器
ch.pipeline().addLast(new StringDecoder());
ch.pipeline().addLast(new StringEncoder());
ch.pipeline().addLast(new NettyChatServerHandler());
}
});
//9. 启动服务端并绑定端口,同时将异步改为同步
ChannelFuture future = serverBootstrap.bind(port);
future.addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (future.isSuccess()) {
System.out.println("端口绑定成功!");
} else {
System.out.println("端口绑定失败!");
}
}
});
System.out.println("聊天室服务端启动成功.");
//10. 关闭通道(并不是真正意义上关闭,而是监听通道关闭的状态)和关闭连接池
future.channel().closeFuture().sync();
} finally {
if (bossGroup != null) {
bossGroup.shutdownGracefully();
}
if (workerGroup != null) {
workerGroup.shutdownGracefully();
}
}
}
public static void main(String[] args) throws InterruptedException {
new NettyChatServer(9998).run();
}
}聊天室客户端编写
- 客户端Handler
java
package com.cys.netty.chat;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
/**
* 聊天室处理类
* @author test
*/
public class NettyChatClientHandler extends SimpleChannelInboundHandler<String> {
/**
* 通道读取就绪事件
*
* @param ctx
* @param msg
* @throws Exception
*/
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(msg);
}
}- 客户端服务
java
package com.cys.netty.chat;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
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 io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import java.util.Scanner;
/**
* 聊天室的客户端
*/
public class NettyChatClient {
/**
* 服务端IP
*/
private String ip;
/**
* 服务端端口号
*/
private int port;
public NettyChatClient(String ip, int port) {
this.ip = ip;
this.port = port;
}
public void run() throws InterruptedException {
//1. 创建线程组
EventLoopGroup group = null;
try {
group = new NioEventLoopGroup();
//2. 创建客户端启动助手
Bootstrap bootstrap = new Bootstrap();
//3. 设置线程组
bootstrap.group(group)
.channel(NioSocketChannel.class)//4. 设置客户端通道实现为NIO
.handler(new ChannelInitializer<SocketChannel>() { //5. 创建一个通道初始化对象
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//6. 向pipeline中添加自定义业务处理handler
//添加编解码器
ch.pipeline().addLast(new StringDecoder());
ch.pipeline().addLast(new StringEncoder());
//添加客户端的处理类
ch.pipeline().addLast(new NettyChatClientHandler());
}
});
//7. 启动客户端,等待连接服务端,同时将异步改为同步
ChannelFuture channelFuture = bootstrap.connect(ip, port).sync();
Channel channel = channelFuture.channel();
System.out.println("-------" + channel.localAddress().toString().substring(1) + "--------");
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String msg = scanner.nextLine();
//向服务端发送消息
channel.writeAndFlush(msg);
}
//8. 关闭通道和关闭连接池
channelFuture.channel().closeFuture().sync();
} finally {
if (group != null) {
group.shutdownGracefully();
}
}
}
public static void main(String[] args) throws InterruptedException {
new NettyChatClient("127.0.0.1", 9998).run();
}
}