org.apache.mina.filter.codec.statemachine.FixedLengthDecodingState Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 org.apache.mina.filter.codec.statemachine;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
/**
* {@link DecodingState} which consumes all received bytes until a configured
* number of read bytes has been reached. Please note that this state can
* produce a buffer with less data than the configured length if the associated
* session has been closed unexpectedly.
*
* @author Apache MINA Project
*/
public abstract class FixedLengthDecodingState implements DecodingState {
private final int length;
private IoBuffer buffer;
/**
* Constructs a new instance using the specified decode length.
*
* @param length the number of bytes to read.
*/
public FixedLengthDecodingState(int length) {
this.length = length;
}
/**
* {@inheritDoc}
*/
@Override
public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception {
if (buffer == null) {
if (in.remaining() >= length) {
int limit = in.limit();
in.limit(in.position() + length);
IoBuffer product = in.slice();
in.position(in.position() + length);
in.limit(limit);
return finishDecode(product, out);
}
buffer = IoBuffer.allocate(length);
buffer.put(in);
return this;
}
if (in.remaining() >= length - buffer.position()) {
int limit = in.limit();
in.limit(in.position() + length - buffer.position());
buffer.put(in);
in.limit(limit);
IoBuffer product = this.buffer;
this.buffer = null;
return finishDecode(product.flip(), out);
}
buffer.put(in);
return this;
}
/**
* {@inheritDoc}
*/
@Override
public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
IoBuffer readData;
if (buffer == null) {
readData = IoBuffer.allocate(0);
} else {
readData = buffer.flip();
buffer = null;
}
return finishDecode(readData, out);
}
/**
* Invoked when this state has consumed the configured number of bytes.
*
* @param product the data.
* @param out the current {@link ProtocolDecoderOutput} used to write
* decoded messages.
* @return the next state if a state transition was triggered (use
* this for loop transitions) or null if
* the state machine has reached its end.
* @throws Exception if the read data violated protocol specification.
*/
protected abstract DecodingState finishDecode(IoBuffer product, ProtocolDecoderOutput out) throws Exception;
}