从入门到超神进阶的Netty群聊系统
作者：墨家巨子@俏如来
本篇文章基于Netty做一个聊天室案例加强Netty的熟练度，案例的效果是服务端可以广播某客户端的消息给所有客户端。每个客户端监听键盘输入来获取消息，然后发送给服务端
服务端
服务端一样的需要创建BossGroup 和 WorkGroup , 然后使用ServerBootStrap 来配置Netty和启动Netty。
public class NettyGroupChatServer {
public static void main(String[] args) {
new NettyGroupChatServer().start();
}
//监听
public void start(){
//循环组
NioEventLoopGroup bossGroup = new NioEventLoopGroup();
NioEventLoopGroup workGroup = new NioEventLoopGroup();
//启动引导
ServerBootstrap bootstrap = new ServerBootstrap();
//Netty配置
bootstrap.group(bossGroup,workGroup)
.option(ChannelOption.SO_BACKLOG,32)
.childOption(ChannelOption.SO_KEEPALIVE,true)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel channel) throws Exception {
//解码器
channel.pipeline().addLast("decoder", new StringDecoder());
//编码器
channel.pipeline().addLast("encoder",new StringEncoder());
//处理器
channel.pipeline().addLast("nettyGroupChatHandler",new NettyGroupChatServerHandler());
}
});
try {
//启动服务
ChannelFuture future = bootstrap.bind(new InetSocketAddress("127.0.0.1", 8888)).sync();
future.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
}finally {
//关闭资源
bossGroup.shutdownGracefully();
workGroup.shutdownGracefully();
}
}
}
服务端处理器我们通过继承 SimpleChannelInboundHandler 入站Handler来处理消息。
其中提供了几个方法
- channelRead0 ()：读取消息
- handlerRemoved ()：客户端断开
- handlerAdded ()：客户端建立连接
- exceptionCaught ()：出现异常
具体代码如下
public class NettyGroupChatServerHandler extends SimpleChannelInboundHandler<String> {
//把所有客户端的channel保存起来
private static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
String message = dateFormat.format(new Date())+":%s:"+msg;
//消息转发给所有的客户端
channels.forEach(channel -> {
if(channel == ctx.channel()){
String sendMsg = String.format(message, "我");
channel.writeAndFlush(sendMsg);
System.out.println(sendMsg);
}else{
String sendMsg = String.format(message, ctx.channel().remoteAddress());
channel.writeAndFlush(sendMsg);
System.out.println(sendMsg);
}
});
}
//断开连接 , 把消息广播给其他客户端
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":断开连接";
channels.writeAndFlush(message);
System.out.println(message);
}
//建立连接
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":加入聊天室";
//自动把消息广播给其客户端
channels.writeAndFlush(message);
//客户端加入组
channels.add(ctx.channel());
System.out.println(message);
}
//出现异常
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.channel().close();
}
//客户端退出
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":退出聊天室";
System.out.println(message);
}
//客户端出于活动
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
String message = dateFormat.format(new Date())+":"+ctx.channel().remoteAddress()+":上线啦";
System.out.println(message);
}
}
客户端
客户端需要创建一个循环事件组，然后通过BootStrap去启动,然后扫描键盘输入作为数据源来把信息发送给服务端
public class NettyGroupChatClient {
public static void main(String[] args) {
new NettyGroupChatClient().start();
}
public void start(){
NioEventLoopGroup eventLoopGroup = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(eventLoopGroup)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel channel) throws Exception {
//解码器
channel.pipeline().addLast("decoder", new StringDecoder());
//编码器
channel.pipeline().addLast("encoder",new StringEncoder());
//处理器
channel.pipeline().addLast("nettyGroupChatClientHandler",new NettyGroupChatClientHandler());
}
});
try {
ChannelFuture future = bootstrap.connect(new InetSocketAddress("127.0.0.1", 8888)).sync();
//通道
Channel channel = future.channel();
//扫描键盘输入
Scanner scanner = new Scanner(System.in);
while(scanner.hasNextLine()){
String message = scanner.nextLine();
//发送数据
channel.writeAndFlush(message);
}
} catch (InterruptedException e) {
}finally {
eventLoopGroup.shutdownGracefully();
}
}
}
对于处理器只需要接收服务端转发过来的消息即可
public class NettyGroupChatClientHandler extends SimpleChannelInboundHandler<String> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(msg);
}
}
启动服务端和多个客户端，效果如下
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