1. 内容概要

1.1 总结

1.1.1 逻辑处理器

ChannelHandler（详见第11章 Pipeline与ChannelHandler）

1.1.2 编程小技巧

public class PacketCodeC {
    ...
    public static final PacketCodeC INSTANCE = new PacketCodeC();
    ...
}

其他类直接调用 PacketCodeC.INSTANCE 即可使用PacketCodeC类的属性和方法
如：

PacketCodeC.INSTANCE.encode(ctx.alloc(), loginRequestPacket);

1.1.3 创建ByteBuf 对象的新方式

 ByteBuf byteBuf = byteBufAllocator.ioBuffer();

其中

byteBufAllocator 是 ctx.alloc() 返回的ByteBuf的分配器
ctx 为 ChannelHandlerContext 通道处理上下文对象

1.1.4 写数据

  ctx.channel().writeAndFlush(buffer);// 写数据

其中

ctx.channel() 返回 Channel

1.1.5 instanceof 用法

作用：判断左边对象是否是右边类的实例/父类

public class ServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        System.out.println(new Date() + ": 客户端开始登录……");
        ByteBuf requestByteBuf = (ByteBuf) msg;

        Packet packet = PacketCodeC.INSTANCE.decode(requestByteBuf);

        if (packet instanceof LoginRequestPacket) {
            // 登录流程
            LoginRequestPacket loginRequestPacket = (LoginRequestPacket) packet;

            LoginResponsePacket loginResponsePacket = new LoginResponsePacket();
            loginResponsePacket.setVersion(packet.getVersion());
            if (valid(loginRequestPacket)) {
                loginResponsePacket.setSuccess(true);
                System.out.println(new Date() + ": 登录成功!");
            } else {
                loginResponsePacket.setReason("账号密码校验失败");
                loginResponsePacket.setSuccess(false);
                System.out.println(new Date() + ": 登录失败!");
            }
            // 登录响应
            ByteBuf responseByteBuf = PacketCodeC.INSTANCE.encode(ctx.alloc(), loginResponsePacket);
            ctx.channel().writeAndFlush(responseByteBuf);
        }
    }

    private boolean valid(LoginRequestPacket loginRequestPacket) {
        return true;
    }
}

2. 课程内容（略，请参考原书）

1　登录流程
2　逻辑处理器
3　客户端发送登录请求 + 返回响应

public class ClientHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        System.out.println(new Date() + ": 客户端开始登录");

        // 创建登录对象
        LoginRequestPacket loginRequestPacket = new LoginRequestPacket();
        loginRequestPacket.setUserId(UUID.randomUUID().toString());
        loginRequestPacket.setUsername("flash");
        loginRequestPacket.setPassword("pwd");

        // 编码
        ByteBuf buffer = PacketCodeC.INSTANCE.encode(ctx.alloc(), loginRequestPacket);

        // 写数据
        ctx.channel().writeAndFlush(buffer);
    }


    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;

        Packet packet = PacketCodeC.INSTANCE.decode(byteBuf);

        if (packet instanceof LoginResponsePacket) {
            LoginResponsePacket loginResponsePacket = (LoginResponsePacket) packet;

            if (loginResponsePacket.isSuccess()) {
                System.out.println(new Date() + ": 客户端登录成功");
            } else {
                System.out.println(new Date() + ": 客户端登录失败，原因：" + loginResponsePacket.getReason());
            }
        }
    }
}