Netty Bootstrap

———— 4.1.72.Final
words: 440    views:    time: 2min
Netty

Bootstrap在Netty中相当于一个组织者的角色，负责初始化装配和启动。

server
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
EventLoopGroup acceptGroup = new NioEventLoopGroup();
EventLoopGroup handleGroup = new NioEventLoopGroup();
ServerBootstrap serverBoot = new ServerBootstrap();
serverBoot.group(acceptGroup, handleGroup).channel(NioServerSocketChannel.class);
serverBoot.option(ChannelOption.SO_BACKLOG, 1024);
serverBoot.childHandler(new ChannelInitializer<SocketChannel>() {
    @Override
    protected void initChannel(SocketChannel channel) throws Exception {
        channel.pipeline().addLast(new ChannelInboundHandlerAdapter(){
            @Override
            public void channelRead(ChannelHandlerContext ctx, Object msg) {
                System.out.println(msg); 
                ctx.writeAndFlush("helle, client");
            }
        });
    }
});

try {
    ChannelFuture channelFuture = serverBoot.bind(8181).sync();
    channelFuture.channel().closeFuture().sync();
} finally {
    acceptGroup.shutdownGracefully();
    handleGroup.shutdownGracefully();
}
client
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Bootstrap clientBoot = new Bootstrap();
EventLoopGroup handleGroup = new NioEventLoopGroup();
clientBoot.group(handleGroup);
clientBoot.channel(NioSocketChannel.class);
clientBoot.option(ChannelOption.TCP_NODELAY, true);
clientBoot.handler(new ChannelInitializer<SocketChannel>() {
    @Override
    protected void initChannel(SocketChannel channel) throws Exception {
        channel.pipeline().addLast(new ChannelInboundHandlerAdapter(){
            @Override
            public void channelActive(ChannelHandlerContext ctx) {
                ctx.writeAndFlush("hello, server");
            }
            
            @Override
            public void channelRead(ChannelHandlerContext ctx, Object msg) {
                System.out.println(msg);
            }
        });
    }
});

try {
    ChannelFuture channelFuture = clientBoot.connect("127.0.0.1", 8181).sync();
    channelFuture.channel().closeFuture().sync();
} finally {
    handleGroup.shutdownGracefully();
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
final ChannelFuture initAndRegister() {
    Channel channel = null;
    try {
        channel = channelFactory.newChannel();
        init(channel);
    } catch (Throwable t) {
        if (channel != null) {
            // channel can be null if newChannel crashed (eg SocketException("too many open files"))
            channel.unsafe().closeForcibly();
            // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor
            return new DefaultChannelPromise(channel, GlobalEventExecutor.INSTANCE).setFailure(t);
        }
        // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor
        return new DefaultChannelPromise(new FailedChannel(), GlobalEventExecutor.INSTANCE).setFailure(t);
    }

    ChannelFuture regFuture = config().group().register(channel);
    if (regFuture.cause() != null) {
        if (channel.isRegistered()) {
            channel.close();
        } else {
            channel.unsafe().closeForcibly();
        }
    }

    // If we are here and the promise is not failed, it's one of the following cases:
    // 1) If we attempted registration from the event loop, the registration has been completed at this point.
    //    i.e. It's safe to attempt bind() or connect() now because the channel has been registered.
    // 2) If we attempted registration from the other thread, the registration request has been successfully
    //    added to the event loop's task queue for later execution.
    //    i.e. It's safe to attempt bind() or connect() now:
    //     because bind() or connect() will be executed *after* the scheduled registration task is executed
    //     because register(), bind(), and connect() are all bound to the same thread.
    return regFuture;
}


参考：