netty自定义解码器

ByteToMessageDecoder

public class CustomDecoder extends ByteToMessageDecoder {

protected void decode(ChannelHandlerContext ctx, ByteBuf buf, List<Object> list) throws Exception {
        try {
            ByteBuffer buffer = buf.nioBuffer();
            int length = buffer.limit();
            byte[] data = new byte[length];
            buffer.get(data);
           
            String json = new String(data, "utf-8");
            System.out.println("json:"+json);
            if(!json.startsWith("{")) {
            return ;
            }
            User user = JSON.parseObject(json, User.class);
            list.add(user); //解码成User对象，从ByteBuf里读取字节流
        } catch (Exception e) {
        e.printStackTrace();
        }
}
}

public class NettyServer {
private int port=8088;

public static void main(String[] args) {
NettyServer server = new NettyServer();
server.run();
}

void run() {
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
public void initChannel(SocketChannel ch) {
ChannelPipeline p =ch.pipeline();
p.addLast(new CustomDecoder()); //handler里的Object msg可以转换成解码后的对象
p.addLast(new SeverHandler());
}}
).option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true);
ChannelFuture f = b.bind(port).sync();
f.channel().closeFuture().sync();
}catch(Exception e) {
e.printStackTrace();
}finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}

public class SeverHandler extends ChannelInboundHandlerAdapter {
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
ctx.writeAndFlush("this is a test!");
User user = (User)msg;
System.out.println("user: "+JSON.toJSONString(user));
}
}