[Java11] Customizing redisCodec for redisCommands

redis command를 날렸을 때 Key는 String, Value는 Object class로 받고 싶어서 커스텀 한 redisCodec입니다.


key는 io.lettuce.core.codec.StringCodec, value는 io.lettuce.core.codec.ByteArrayCodec 참조하여 구현

import io.lettuce.core.codec.RedisCodec;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.util.CharsetUtil;
import org.springframework.util.SerializationUtils;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;

public class ObjectValueCodec<T> implements RedisCodec<String, T> {

	private static final byte[] EMPTY = new byte[0];
	private final Charset charset = Charset.defaultCharset();

	public ObjectValueCodec() {
	}

	@Override
	public String decodeKey(ByteBuffer bytes) {
		return Unpooled.wrappedBuffer(bytes).toString(charset);
	}

	@Override
	public T decodeValue(ByteBuffer bytes) {
		byte[] ba = getBytes(bytes);
		return (T) SerializationUtils.deserialize(ba); // bytes to object
	}

	@Override
	public ByteBuffer encodeKey(String key) {
		return encodeAndAllocateBuffer(key);
	}

	@Override
	public ByteBuffer encodeValue(T value) {
		byte[] ba = SerializationUtils.serialize(value); // object to bytes
		return ByteBuffer.wrap(ba);
	}

	private static byte[] getBytes(ByteBuffer buffer) {

		int remaining = buffer.remaining();

		if (remaining == 0) {
			return EMPTY;
		}

		byte[] b = new byte[remaining];
		buffer.get(b);
		return b;
	}

	private ByteBuffer encodeAndAllocateBuffer(String key) {
		if (key == null) {
			return ByteBuffer.wrap(EMPTY);
		}

		CharsetEncoder encoder = CharsetUtil.encoder(charset);
		ByteBuffer buffer = ByteBuffer.allocate((int) (encoder.maxBytesPerChar() * key.length()));

		ByteBuf byteBuf = Unpooled.wrappedBuffer(buffer);
		byteBuf.clear();
		encode(key, byteBuf);
		buffer.limit(byteBuf.writerIndex());

		return buffer;
	}

	private void encode(String str, ByteBuf target) {
		if (str == null) {
			return;
		}

		CharsetEncoder encoder = CharsetUtil.encoder(charset);
		int length = (int) ((double) str.length() * encoder.maxBytesPerChar());
		target.ensureWritable(length);
		try {
			final ByteBuffer dstBuf = target.nioBuffer(0, length);
			final int pos = dstBuf.position();
			CoderResult cr = encoder.encode(CharBuffer.wrap(str), dstBuf, true);
			if (!cr.isUnderflow()) {
				cr.throwException();
			}
			cr = encoder.flush(dstBuf);
			if (!cr.isUnderflow()) {
				cr.throwException();
			}
			target.writerIndex(target.writerIndex() + dstBuf.position() - pos);
		} catch (CharacterCodingException x) {
			throw new IllegalStateException(x);
		}
	}
}

 
사용법

	@Bean
	public RedisCommands<String, UserInfoVO> userRedisCommands() {
		return redisClient.connect(new ObjectValueCodec<UserInfoVO>()).sync();
	}