b57d9f307f
- write() now accepts a ChannelPromise and returns ChannelFuture as most users expected. It makes the user's life much easier because it is now much easier to get notified when a specific message has been written. - flush() does not create a ChannelPromise nor returns ChannelFuture. It is now similar to what read() looks like.
123 lines
4.2 KiB
Java
123 lines
4.2 KiB
Java
/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.ChannelOutboundHandlerAdapter;
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import io.netty.channel.ChannelPromise;
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import io.netty.util.ReferenceCountUtil;
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import io.netty.util.internal.TypeParameterMatcher;
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/**
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* {@link ChannelOutboundHandlerAdapter} which encodes message in a stream-like fashion from one message to an
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* {@link ByteBuf}.
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*
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*
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* Example implementation which encodes {@link Integer}s to a {@link ByteBuf}.
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*
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* <pre>
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* public class IntegerEncoder extends {@link MessageToByteEncoder}<{@link Integer}> {
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* {@code @Override}
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* public void encode({@link ChannelHandlerContext} ctx, {@link Integer} msg, {@link ByteBuf} out)
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* throws {@link Exception} {
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* out.writeInt(msg);
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* }
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* }
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* </pre>
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*/
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public abstract class MessageToByteEncoder<I> extends ChannelOutboundHandlerAdapter {
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private final TypeParameterMatcher matcher;
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private final boolean preferDirect;
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protected MessageToByteEncoder() {
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this(true);
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}
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protected MessageToByteEncoder(Class<? extends I> outboundMessageType) {
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this(outboundMessageType, true);
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}
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protected MessageToByteEncoder(boolean preferDirect) {
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matcher = TypeParameterMatcher.find(this, MessageToByteEncoder.class, "I");
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this.preferDirect = preferDirect;
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}
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protected MessageToByteEncoder(Class<? extends I> outboundMessageType, boolean preferDirect) {
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matcher = TypeParameterMatcher.get(outboundMessageType);
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this.preferDirect = preferDirect;
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}
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public boolean acceptOutboundMessage(Object msg) throws Exception {
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return matcher.match(msg);
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}
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@Override
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public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
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ByteBuf buf = null;
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try {
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if (acceptOutboundMessage(msg)) {
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@SuppressWarnings("unchecked")
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I cast = (I) msg;
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if (buf == null) {
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if (preferDirect) {
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buf = ctx.alloc().ioBuffer();
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} else {
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buf = ctx.alloc().heapBuffer();
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}
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}
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try {
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encode(ctx, cast, buf);
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} finally {
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ReferenceCountUtil.release(cast);
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}
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if (buf.isReadable()) {
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ctx.write(buf, promise);
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} else {
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buf.release();
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ctx.write(Unpooled.EMPTY_BUFFER, promise);
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}
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buf = null;
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} else {
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ctx.write(msg, promise);
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}
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} catch (EncoderException e) {
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throw e;
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} catch (Throwable e) {
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throw new EncoderException(e);
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} finally {
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if (buf != null) {
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buf.release();
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}
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}
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}
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/**
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* Encode a message into a {@link ByteBuf}. This method will be called for each written message that can be handled
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* by this encoder.
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*
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* @param ctx the {@link ChannelHandlerContext} which this {@link MessageToByteEncoder} belongs to
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* @param msg the message to encode
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* @param out the {@link ByteBuf} into which the encoded message will be written
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* @throws Exception is thrown if an error accour
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*/
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protected abstract void encode(ChannelHandlerContext ctx, I msg, ByteBuf out) throws Exception;
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}
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