io.netty.handler.codec.LengthFieldPrepender Maven / Gradle / Ivy
Go to download
This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* 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.
*
* For example, {@link LengthFieldPrepender}(2) will encode the
* following 12-bytes string:
*
* +----------------+
* | "HELLO, WORLD" |
* +----------------+
*
* into the following:
*
* +--------+----------------+
* + 0x000C | "HELLO, WORLD" |
* +--------+----------------+
*
* 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)):
*
* +--------+----------------+
* + 0x000E | "HELLO, WORLD" |
* +--------+----------------+
*
*/
@Sharable
public class LengthFieldPrepender extends MessageToMessageEncoder {
private final ByteOrder byteOrder;
private final int lengthFieldLength;
private final boolean lengthIncludesLengthFieldLength;
private final int lengthAdjustment;
/**
* Creates a new instance.
*
* @param lengthFieldLength the length of the prepended length field.
* Only 1, 2, 3, 4, and 8 are allowed.
*
* @throws IllegalArgumentException
* if {@code lengthFieldLength} is not 1, 2, 3, 4, or 8
*/
public LengthFieldPrepender(int lengthFieldLength) {
this(lengthFieldLength, false);
}
/**
* Creates a new instance.
*
* @param lengthFieldLength the length of the prepended length field.
* Only 1, 2, 3, 4, and 8 are allowed.
* @param lengthIncludesLengthFieldLength
* if {@code true}, the length of the prepended
* length field is added to the value of the
* prepended length field.
*
* @throws IllegalArgumentException
* if {@code lengthFieldLength} is not 1, 2, 3, 4, or 8
*/
public LengthFieldPrepender(int lengthFieldLength, boolean lengthIncludesLengthFieldLength) {
this(lengthFieldLength, 0, lengthIncludesLengthFieldLength);
}
/**
* Creates a new instance.
*
* @param lengthFieldLength the length of the prepended length field.
* Only 1, 2, 3, 4, and 8 are allowed.
* @param lengthAdjustment the compensation value to add to the value
* of the length field
*
* @throws IllegalArgumentException
* if {@code lengthFieldLength} is not 1, 2, 3, 4, or 8
*/
public LengthFieldPrepender(int lengthFieldLength, int lengthAdjustment) {
this(lengthFieldLength, lengthAdjustment, false);
}
/**
* Creates a new instance.
*
* @param lengthFieldLength the length of the prepended length field.
* Only 1, 2, 3, 4, and 8 are allowed.
* @param lengthAdjustment the compensation value to add to the value
* of the length field
* @param lengthIncludesLengthFieldLength
* if {@code true}, the length of the prepended
* length field is added to the value of the
* prepended length field.
*
* @throws IllegalArgumentException
* if {@code lengthFieldLength} is not 1, 2, 3, 4, or 8
*/
public LengthFieldPrepender(int lengthFieldLength, int lengthAdjustment, boolean lengthIncludesLengthFieldLength) {
this(ByteOrder.BIG_ENDIAN, lengthFieldLength, lengthAdjustment, lengthIncludesLengthFieldLength);
}
/**
* Creates a new instance.
*
* @param byteOrder the {@link ByteOrder} of the length field
* @param lengthFieldLength the length of the prepended length field.
* Only 1, 2, 3, 4, and 8 are allowed.
* @param lengthAdjustment the compensation value to add to the value
* of the length field
* @param lengthIncludesLengthFieldLength
* if {@code true}, the length of the prepended
* length field is added to the value of the
* prepended length field.
*
* @throws IllegalArgumentException
* if {@code lengthFieldLength} is not 1, 2, 3, 4, or 8
*/
public LengthFieldPrepender(
ByteOrder byteOrder, int lengthFieldLength,
int lengthAdjustment, boolean lengthIncludesLengthFieldLength) {
if (lengthFieldLength != 1 && lengthFieldLength != 2 &&
lengthFieldLength != 3 && lengthFieldLength != 4 &&
lengthFieldLength != 8) {
throw new IllegalArgumentException(
"lengthFieldLength must be either 1, 2, 3, 4, or 8: " +
lengthFieldLength);
}
this.byteOrder = ObjectUtil.checkNotNull(byteOrder, "byteOrder");
this.lengthFieldLength = lengthFieldLength;
this.lengthIncludesLengthFieldLength = lengthIncludesLengthFieldLength;
this.lengthAdjustment = lengthAdjustment;
}
@Override
protected void encode(ChannelHandlerContext ctx, ByteBuf msg, List