前言
在前面我们讲解了Netty的基本使用，本次我们将使用Netty来完成一个群聊系统，实现服务器端和客户端之间的数据简单通讯;
群聊系统基本要求：
- 服务器端可监测客户端上线、离线、并转发客户端消息；
- 客户端可群发消息给其它用户，也可接收其它客户发送的消息；
代码示例
服务端：
public class GroupChatServer {
private String host;
private int port;
public GroupChatServer(String host, int port) {
this.host = host;
this.port = port;
}
public void start() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128) // 设置线程队列的连接个数
.childOption(ChannelOption.SO_KEEPALIVE, true) // 设置保持活动连接状态
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
// 获取pipeline
ChannelPipeline pipeline = socketChannel.pipeline();
// 添加解码器
pipeline.addLast(new StringDecoder());
// 添加编码器
pipeline.addLast(new StringEncoder());
// 添加自定义业务处理handler
pipeline.addLast(new GroupChatServerHandler());
}
});
System.out.println("Netty群聊服务器已启动~");
ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
channelFuture.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new GroupChatServer("127.0.0.1", 8899).start();
}
}
服务端自定义handler：
public class GroupChatServerHandler extends SimpleChannelInboundHandler<String> {
private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
private static SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
/**
* 连接建立事件
*
* @param ctx
* @throws Exception
*/
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
Channel channel = ctx.channel();
String msg = channel.remoteAddress() + "加入了聊天~";
channelGroup.writeAndFlush(msg);
// 将channel加入到channelGroup
channelGroup.add(channel);
}
/**
* 断开连接事件
*
* @param ctx
* @throws Exception
*/
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
Channel channel = ctx.channel();
String msg = "[Server]：" + channel.remoteAddress() + "下线啦~";
channelGroup.writeAndFlush(msg);
}
/**
* channel处理活动状态事件
*
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println(simpleDateFormat.format(new Date()) + "/" + ctx.channel().remoteAddress() + "上线啦~");
}
/**
* channel处于不活动状态
*
* @param ctx
* @throws Exception
*/
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println(simpleDateFormat.format(new Date()) + "/" + ctx.channel().remoteAddress() + " 离线了~");
}
/**
* 读取数据事件
*
* @param ctx
* @param s
* @throws Exception
*/
@Override
protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
Channel channel = ctx.channel();
System.out.println(simpleDateFormat.format(new Date()) + "/" + "服务器接收到来自[" + channel.remoteAddress() + "]的消息，内容为[" + s + "]");
System.out.println("服务器开始进行消息转发。。。");
for (Channel ch : channelGroup) {
if (channel != ch) {
ch.writeAndFlush(channel.remoteAddress() + "说：" + s);
}
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
客户端：
public class GroupChatClient {
private String serverHost;
private int serverPort;
public GroupChatClient(String serverHost, int serverPort) {
this.serverHost = serverHost;
this.serverPort = serverPort;
}
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 socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
// 添加解码器
pipeline.addLast(new StringDecoder());
// 添加编码器
pipeline.addLast(new StringEncoder());
// 添加自定义业务处理handler
pipeline.addLast(new GroupChatClientHandler());
}
});
ChannelFuture channelFuture = bootstrap.connect(serverHost, serverPort).sync();
Channel channel = channelFuture.channel();
System.out.println("---" + channel.localAddress() + "---");
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String msg = scanner.nextLine();
channel.writeAndFlush(msg);
}
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new GroupChatClient("127.0.0.1", 8899).start();
}
}
客户端自定义handler：
public class GroupChatClientHandler extends SimpleChannelInboundHandler<String> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
// 输出打印消息
System.out.println(s);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
通讯演示：
服务端：
Netty群聊服务器已启动~
2020-02-04 12:22:11//127.0.0.1:4099上线啦~
2020-02-04 12:22:14//127.0.0.1:4141上线啦~
2020-02-04 12:22:24/服务器接收到来自[/127.0.0.1:4099]的消息，内容为[我是4099]
服务器开始进行消息转发。。。
2020-02-04 12:22:31/服务器接收到来自[/127.0.0.1:4141]的消息，内容为[我是4141]
服务器开始进行消息转发。。。
client1：
---/127.0.0.1:4099---
/127.0.0.1:4141加入了聊天~
我是4099
/127.0.0.1:4141说：我是4141
client2：
---/127.0.0.1:4141---
/127.0.0.1:4099说：我是4099
我是4141
