com.godmao.mqserver.handler.TopicSubscribeCancelMessageEncoderHandler Maven / Gradle / Ivy

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package com.godmao.mqserver.handler;

import com.godmao.mqserver.message.TopicSubscribeCancelMessage;
import com.godmao.netty.handler.AbstractEncoderHandler;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.ChannelHandler;

import java.nio.charset.StandardCharsets;
import java.util.Set;

@ChannelHandler.Sharable
public class TopicSubscribeCancelMessageEncoderHandler extends AbstractEncoderHandler {

    public static final TopicSubscribeCancelMessageEncoderHandler INSTANCE = new TopicSubscribeCancelMessageEncoderHandler();

    public ByteBuf encode(TopicSubscribeCancelMessage msg) {
        final Set topics = msg.getTopics();


        // 预估缓冲区大小
        int estimatedSize = 5; // cmd(1 byte) + isAll(1 byte) + topics.size(4 bytes)
        final byte[][] _topics_bytes = new byte[topics.size()][];

        int index = 0;
        for (String topic : topics) {
            final byte[] topic_bytes = topic.getBytes(StandardCharsets.UTF_8);
            _topics_bytes[index++] = topic_bytes;
            estimatedSize += 4 + topic_bytes.length;
        }


        final ByteBuf byteBuf = ByteBufAllocator.DEFAULT.buffer(estimatedSize);
        byteBuf.writeByte(msg.getCmd());// 1
        byteBuf.writeInt(topics.size());// 4
        //4
        for (final byte[] topic_bytes : _topics_bytes) {
            byteBuf.writeInt(topic_bytes.length);
            byteBuf.writeBytes(topic_bytes);
        }
        return byteBuf;
    }
}