Java tutorial
/* * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.github.pgasync.impl.netty; import com.github.pgasync.impl.io.*; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.ByteToMessageDecoder; import java.nio.ByteBuffer; import java.util.HashMap; import java.util.List; import java.util.Map; /** * Decodes incoming bytes to PostgreSQL V3 protocol message instances. * * @author Antti Laisi */ class ByteBufMessageDecoder extends ByteToMessageDecoder { static final Map<Byte, Decoder<?>> DECODERS = new HashMap<>(); static { for (Decoder<?> decoder : new Decoder<?>[] { new ErrorResponseDecoder(), new AuthenticationDecoder(), new ReadyForQueryDecoder(), new RowDescriptionDecoder(), new CommandCompleteDecoder(), new DataRowDecoder(), new NotificationResponseDecoder() }) { DECODERS.put(decoder.getMessageId(), decoder); } } @Override protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception { if (in.readableBytes() == 0) { return; } byte id = in.readByte(); int length = in.readInt(); Decoder<?> decoder = DECODERS.get(id); try { if (decoder != null) { ByteBuffer buffer = in.nioBuffer(); out.add(decoder.read(buffer)); in.skipBytes(buffer.position()); } else { in.skipBytes(length - 4); } } catch (Throwable t) { // broad catch as otherwise the exception is silently dropped ctx.fireExceptionCaught(t); } } }