netty解决tcp粘包和拆包问题

tcp为了提高效率会将多个数据包批量发送过来，所以就会存在粘包和拆包的问题。使用Netty,可以通过自定义协议+编解码器来解决粘包和拆包的问题。

1.定义协议

public class MessageProtocol {

    private int len;

    private byte[] content;

    public int getLen() {
        return len;
    }

    public void setLen(int len) {
        this.len = len;
    }

    public byte[] getContent() {
        return content;
    }

    public void setContent(byte[] content) {
        this.content = content;
    }
}

2.自定义编码器和解码器

public class MyMessageEncoder extends MessageToByteEncoder<MessageProtocol> {
    @Override
    protected void encode(ChannelHandlerContext ctx, MessageProtocol msg, ByteBuf out) throws Exception {
        System.out.println("编码器被调用");
        out.writeInt(msg.getLen());
        out.writeBytes(msg.getContent());
    }
}

public class MyMessageDecoder extends ReplayingDecoder<Void> {
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf