Java tutorial
/* * Copyright 2014 The Netty Project * * The Netty Project licenses this file to you 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 io.netty.handler.codec.stomp; import io.netty.buffer.ByteBuf; import io.netty.buffer.ByteBufUtil; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.MessageToMessageEncoder; import io.netty.util.CharsetUtil; import java.util.List; import java.util.Map.Entry; /** * Encodes a {@link StompFrame} or a {@link StompSubframe} into a {@link ByteBuf}. */ public class StompSubframeEncoder extends MessageToMessageEncoder<StompSubframe> { @Override protected void encode(ChannelHandlerContext ctx, StompSubframe msg, List<Object> out) throws Exception { if (msg instanceof StompFrame) { StompFrame frame = (StompFrame) msg; ByteBuf frameBuf = encodeFrame(frame, ctx); out.add(frameBuf); ByteBuf contentBuf = encodeContent(frame, ctx); out.add(contentBuf); } else if (msg instanceof StompHeadersSubframe) { StompHeadersSubframe frame = (StompHeadersSubframe) msg; ByteBuf buf = encodeFrame(frame, ctx); out.add(buf); } else if (msg instanceof StompContentSubframe) { StompContentSubframe stompContentSubframe = (StompContentSubframe) msg; ByteBuf buf = encodeContent(stompContentSubframe, ctx); out.add(buf); } } private static ByteBuf encodeContent(StompContentSubframe content, ChannelHandlerContext ctx) { if (content instanceof LastStompContentSubframe) { ByteBuf buf = ctx.alloc().buffer(content.content().readableBytes() + 1); buf.writeBytes(content.content()); buf.writeByte(StompConstants.NUL); return buf; } else { return content.content().retain(); } } private static ByteBuf encodeFrame(StompHeadersSubframe frame, ChannelHandlerContext ctx) { ByteBuf buf = ctx.alloc().buffer(); buf.writeCharSequence(frame.command().toString(), CharsetUtil.UTF_8); buf.writeByte(StompConstants.LF); for (Entry<CharSequence, CharSequence> entry : frame.headers()) { ByteBufUtil.writeUtf8(buf, entry.getKey()); buf.writeByte(StompConstants.COLON); ByteBufUtil.writeUtf8(buf, entry.getValue()); buf.writeByte(StompConstants.LF); } buf.writeByte(StompConstants.LF); return buf; } }