LengthFieldPrepender.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.checkPositiveOrZero;

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

import java.nio.ByteOrder;
import java.util.List;


/**
 * An encoder that prepends the length of the message.  The length value is
 * prepended as a binary form.
 * <p>
 * For example, <tt>{@link LengthFieldPrepender}(2)</tt> will encode the
 * following 12-bytes string:
 * <pre>
 * +----------------+
 * | "HELLO, WORLD" |
 * +----------------+
 * </pre>
 * into the following:
 * <pre>
 * +--------+----------------+
 * + 0x000C | "HELLO, WORLD" |
 * +--------+----------------+
 * </pre>
 * If you turned on the {@code lengthIncludesLengthFieldLength} flag in the
 * constructor, the encoded data would look like the following
 * (12 (original data) + 2 (prepended data) = 14 (0xE)):
 * <pre>
 * +--------+----------------+
 * + 0x000E | "HELLO, WORLD" |
 * +--------+----------------+
 * </pre>
 */
@Sharable
public class LengthFieldPrepender extends MessageToMessageEncoder<ByteBuf> {

    private final ByteOrder byteOrder;
    private final int lengthFieldLength;
    private final boolean lengthIncludesLengthFieldLength;
// ... (143 more lines)