001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.mina.filter.util; 021 022import org.apache.mina.core.filterchain.IoFilter; 023import org.apache.mina.core.filterchain.IoFilterAdapter; 024import org.apache.mina.core.session.IoEventType; 025import org.apache.mina.core.session.IoSession; 026import org.apache.mina.core.write.WriteRequest; 027import org.apache.mina.core.write.WriteRequestWrapper; 028 029/** 030 * An abstract {@link IoFilter} that simplifies the implementation of 031 * an {@link IoFilter} that filters an {@link IoEventType#WRITE} event. 032 * 033 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 034 * 035 */ 036public abstract class WriteRequestFilter extends IoFilterAdapter { 037 @Override 038 public void filterWrite(NextFilter nextFilter, IoSession session, WriteRequest writeRequest) throws Exception { 039 Object filteredMessage = doFilterWrite(nextFilter, session, writeRequest); 040 if (filteredMessage != null && filteredMessage != writeRequest.getMessage()) { 041 nextFilter.filterWrite(session, new FilteredWriteRequest(filteredMessage, writeRequest)); 042 } else { 043 nextFilter.filterWrite(session, writeRequest); 044 } 045 } 046 047 @Override 048 public void messageSent(NextFilter nextFilter, IoSession session, WriteRequest writeRequest) throws Exception { 049 if (writeRequest instanceof FilteredWriteRequest) { 050 FilteredWriteRequest req = (FilteredWriteRequest) writeRequest; 051 if (req.getParent() == this) { 052 nextFilter.messageSent(session, req.getParentRequest()); 053 return; 054 } 055 } 056 057 nextFilter.messageSent(session, writeRequest); 058 } 059 060 protected abstract Object doFilterWrite(NextFilter nextFilter, IoSession session, WriteRequest writeRequest) 061 throws Exception; 062 063 private class FilteredWriteRequest extends WriteRequestWrapper { 064 private final Object filteredMessage; 065 066 public FilteredWriteRequest(Object filteredMessage, WriteRequest writeRequest) { 067 super(writeRequest); 068 069 if (filteredMessage == null) { 070 throw new IllegalArgumentException("filteredMessage"); 071 } 072 this.filteredMessage = filteredMessage; 073 } 074 075 public WriteRequestFilter getParent() { 076 return WriteRequestFilter.this; 077 } 078 079 @Override 080 public Object getMessage() { 081 return filteredMessage; 082 } 083 } 084}