DelimiterBasedFrameDecoder.java — netty Source File

Source Code

/*
 * Copyright 2012 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:
 *
 *   https://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;

import static io.netty.util.internal.ObjectUtil.checkPositive;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.internal.ObjectUtil;

import java.util.List;

/**
 * A decoder that splits the received {@link ByteBuf}s by one or more
 * delimiters.  It is particularly useful for decoding the frames which ends
 * with a delimiter such as {@link Delimiters#nulDelimiter() NUL} or
 * {@linkplain Delimiters#lineDelimiter() newline characters}.
 *
 * <h3>Predefined delimiters</h3>
 * <p>
 * {@link Delimiters} defines frequently used delimiters for convenience' sake.
 *
 * <h3>Specifying more than one delimiter</h3>
 * <p>
 * {@link DelimiterBasedFrameDecoder} allows you to specify more than one
 * delimiter.  If more than one delimiter is found in the buffer, it chooses
 * the delimiter which produces the shortest frame.  For example, if you have
 * the following data in the buffer:
 * <pre>
 * +--------------+
 * | ABC\nDEF\r\n |
 * +--------------+
 * </pre>
 * a {@link DelimiterBasedFrameDecoder}({@link Delimiters#lineDelimiter() Delimiters.lineDelimiter()})
 * will choose {@code '\n'} as the first delimiter and produce two frames:
 * <pre>
 * +-----+-----+
 * | ABC | DEF |
 * +-----+-----+
 * </pre>
 * rather than incorrectly choosing {@code '\r\n'} as the first delimiter:
 * <pre>
 * +----------+
 * | ABC\nDEF |
 * +----------+
 * </pre>
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