实例要求:
- 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（非阻塞）
- 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：通过channel 可以无阻塞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(有服务器转发得到)
- 目的：进一步理解Netty非阻塞网络编程机制
代码如下：
服务器
public class GroupChatServer {
// 监听端口
private int port;
public GroupChatServer(int port) {
this.port = port;
}
// 编写start方法，监听客户端请求
public void run() throws InterruptedException {
// 创建2个线程组
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
// -------------------------------------------------
// 编写引导类，配置启动配置
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true)
// 配置处理类
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
// 获取到pipeline
ChannelPipeline pipeline = socketChannel.pipeline();
// 加入编解码器
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
// 加入自己的业务处理类
pipeline.addLast(new GroupChaServerHandler());
}
});
System.out.println("服务器启动...");
ChannelFuture channelFuture = serverBootstrap.bind(port).sync();
// 监听关闭
channelFuture.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws InterruptedException {
GroupChatServer groupChatServer = new GroupChatServer(7000);
groupChatServer.run();
}
}
服务器端处理器
public class GroupChaServerHandler extends SimpleChannelInboundHandler<String> {
// 将所有连接的客户端通道都加入到此group中
private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
/**
*handlerAdded表示连接事件，一旦有客户端连接，第一个执行
* @param ctx
* @throws Exception
*/
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
// 将该客户端加入聊天的信息发送给其他客户端
Channel channel = ctx.channel();
channelGroup.writeAndFlush("[客户端]" + channel.remoteAddress() + "加入聊天");
// 将该客户端加入到Group
channelGroup.add(channel);
}
/**
* 断开连接，有客户端断开连接，将执行此方法
* @param ctx
* @throws Exception
*/
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
// 将该客户端断开连接的信息发送给其他客户端
Channel channel = ctx.channel();
channelGroup.writeAndFlush("[客户端]" + channel.remoteAddress() + "离开聊天");
}
@Override
protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
// 获取当前的channel
Channel channel = channelHandlerContext.channel();
// 遍历channnelGroup
channelGroup.forEach(ch -> {
if(channel != ch) { //不是当前的channel,转发消息
ch.writeAndFlush("[客户]" + channel.remoteAddress() + " 发送了消息" + msg + "\n");
}else {//回显自己发送的消息给自己
ch.writeAndFlush("[自己]发送了消息" + msg + "\n");
}
});
}
//表示channel 处于活动状态, 提示 xx上线
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println(ctx.channel().remoteAddress() + " 上线了~");
}
//表示channel 处于不活动状态, 提示 xx离线了
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println(ctx.channel().remoteAddress() + " 离线了~");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
客户端
public class GroupChatClient {
//属性
private final String host;
private final int port;
public GroupChatClient(String host, int port) {
this.host = host;
this.port = port;
}
public void run() throws Exception{
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap()
.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//得到pipeline
ChannelPipeline pipeline = ch.pipeline();
//加入相关handler
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
//加入自定义的handler
pipeline.addLast(new GroupChatClientHandler());
}
});
ChannelFuture channelFuture = bootstrap.connect(host, port).sync();
//得到channel
Channel channel = channelFuture.channel();
System.out.println("-------" + channel.localAddress()+ "--------");
//客户端需要输入信息，创建一个扫描器
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String msg = scanner.nextLine();
//通过channel 发送到服务器端
channel.writeAndFlush(msg + "\r\n");
}
}finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new GroupChatClient("127.0.0.1", 7000).run();
}
}
客户端处理器
public class GroupChatClientHandler extends SimpleChannelInboundHandler<String> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(msg.trim());
}
}
