org.apache.mina.filter.codec.statemachine.DecodingStateProtocolDecoder Maven / Gradle / Ivy
/**
* Copyright 2007-2015, Kaazing Corporation. All rights reserved.
*
* Licensed 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 java.util.Queue;
import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolDecoder;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
import org.apache.mina.util.CircularQueue;
/**
* {@link ProtocolDecoder} which uses a {@link DecodingState} to decode data.
* Use a {@link DecodingStateMachine} as {@link DecodingState} to create
* a state machine which can decode your protocol.
*
* NOTE: This is a stateful decoder. You should create one instance per session.
*
*
* @author Apache MINA Project
*/
public class DecodingStateProtocolDecoder implements ProtocolDecoder {
private final DecodingState state;
private final Queue undecodedBuffers = new CircularQueue();
private IoSession session;
/**
* Creates a new instance using the specified {@link DecodingState}
* instance.
*
* @param state the {@link DecodingState}.
* @throws NullPointerException if the specified state is null
.
*/
public DecodingStateProtocolDecoder(DecodingState state) {
if (state == null) {
throw new NullPointerException("state");
}
this.state = state;
}
/**
* {@inheritDoc}
*/
public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out)
throws Exception {
if (this.session == null) {
this.session = session;
} else if (this.session != session) {
throw new IllegalStateException(
getClass().getSimpleName() + " is a stateful decoder. " +
"You have to create one per session.");
}
undecodedBuffers.offer(in);
for (;;) {
IoBuffer b = undecodedBuffers.peek();
if (b == null) {
break;
}
int oldRemaining = b.remaining();
state.decode(b, out);
int newRemaining = b.remaining();
if (newRemaining != 0) {
if (oldRemaining == newRemaining) {
throw new IllegalStateException(
DecodingState.class.getSimpleName() + " must " +
"consume at least one byte per decode().");
}
} else {
undecodedBuffers.poll();
}
}
}
/**
* {@inheritDoc}
*/
public void finishDecode(IoSession session, ProtocolDecoderOutput out)
throws Exception {
state.finishDecode(out);
}
/**
* {@inheritDoc}
*/
public void dispose(IoSession session) throws Exception {
// Do nothing
}
}