defaultiofilterchainbuilder.java

mina是以Java实现的一个开源的网络程序框架

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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.core.filterchain;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.CopyOnWriteArrayList;

import org.apache.mina.core.filterchain.IoFilter.NextFilter;
import org.apache.mina.core.filterchain.IoFilterChain.Entry;
import org.apache.mina.core.session.IoSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The default implementation of {@link IoFilterChainBuilder} which is useful
 * in most cases.  {@link DefaultIoFilterChainBuilder} has an identical interface
 * with {@link IoFilter}; it contains a list of {@link IoFilter}s that you can
 * modify. The {@link IoFilter}s which are added to this builder will be appended
 * to the {@link IoFilterChain} when {@link #buildFilterChain(IoFilterChain)} is
 * invoked.
 * <p>
 * However, the identical interface doesn't mean that it behaves in an exactly
 * same way with {@link IoFilterChain}.  {@link DefaultIoFilterChainBuilder}
 * doesn't manage the life cycle of the {@link IoFilter}s at all, and the
 * existing {@link IoSession}s won't get affected by the changes in this builder.
 * {@link IoFilterChainBuilder}s affect only newly created {@link IoSession}s.
 *
 * <pre>
 * IoAcceptor acceptor = ...;
 * DefaultIoFilterChainBuilder builder = acceptor.getFilterChain();
 * builder.addLast( "myFilter", new MyFilter() );
 * ...
 * </pre>
 *
 * @author The Apache MINA Project ([e-mail])
 * @version $Rev: 594846 $, $Date: 2007-11-14 13:03:07 +0100 (Wed, 14 Nov 2007) $
 * @org.apache.xbean.XBean
 */
public class DefaultIoFilterChainBuilder implements IoFilterChainBuilder {
    
    private final Logger logger = LoggerFactory.getLogger(getClass());
    private final List<Entry> entries;

    /**
     * Creates a new instance with an empty filter list.
     */
    public DefaultIoFilterChainBuilder() {
        entries = new CopyOnWriteArrayList<Entry>();
    }

    /**
     * Creates a new copy of the specified {@link DefaultIoFilterChainBuilder}.
     */
    public DefaultIoFilterChainBuilder(DefaultIoFilterChainBuilder filterChain) {
        if (filterChain == null) {
            throw new NullPointerException("filterChain");
        }
        entries = new CopyOnWriteArrayList<Entry>(filterChain.entries);
    }

    /**
     * @see IoFilterChain#getEntry(String)
     */
    public Entry getEntry(String name) {
        for (Entry e: entries) {
            if (e.getName().equals(name)) {
                return e;
            }
        }

        return null;
    }

    /**
     * @see IoFilterChain#getEntry(IoFilter)
     */
    public Entry getEntry(IoFilter filter) {
        for (Entry e: entries) {
            if (e.getFilter() == filter) {
                return e;
            }
        }

        return null;
    }

    /**
     * @see IoFilterChain#getEntry(Class)
     */
    public Entry getEntry(Class<? extends IoFilter> filterType) {
        for (Entry e: entries) {
            if (filterType.isAssignableFrom(e.getFilter().getClass())) {
                return e;
            }
        }

        return null;
    }

    /**
     * @see IoFilterChain#get(String)
     */
    public IoFilter get(String name) {
        Entry e = getEntry(name);
        if (e == null) {
            return null;
        }

        return e.getFilter();
    }

    /**
     * @see IoFilterChain#get(Class)
     */
    public IoFilter get(Class<? extends IoFilter> filterType) {
        Entry e = getEntry(filterType);
        if (e == null) {
            return null;
        }

        return e.getFilter();
    }

    /**
     * @see IoFilterChain#getAll()
     */
    public List<Entry> getAll() {
        return new ArrayList<Entry>(entries);
    }

    /**
     * @see IoFilterChain#getAllReversed()
     */
    public List<Entry> getAllReversed() {
        List<Entry> result = getAll();
        Collections.reverse(result);
        return result;
    }

    /**
     * @see IoFilterChain#contains(String)
     */
    public boolean contains(String name) {
        return getEntry(name) != null;
    }

    /**
     * @see IoFilterChain#contains(IoFilter)
     */
    public boolean contains(IoFilter filter) {
        return getEntry(filter) != null;
    }

    /**
     * @see IoFilterChain#contains(Class)
     */
    public boolean contains(Class<? extends IoFilter> filterType) {
        return getEntry(filterType) != null;
    }

    /**
     * @see IoFilterChain#addFirst(String, IoFilter)
     */
    public synchronized void addFirst(String name, IoFilter filter) {
        register(0, new EntryImpl(name, filter));
    }

    /**
     * @see IoFilterChain#addLast(String, IoFilter)
     */
    public synchronized void addLast(String name, IoFilter filter) {
        register(entries.size(), new EntryImpl(name, filter));
    }

    /**
     * @see IoFilterChain#addBefore(String, String, IoFilter)
     */
    public synchronized void addBefore(String baseName, String name,
            IoFilter filter) {
        checkBaseName(baseName);

        for (ListIterator<Entry> i = entries.listIterator(); i.hasNext();) {
            Entry base = i.next();
            if (base.getName().equals(baseName)) {
                register(i.previousIndex(), new EntryImpl(name, filter));
                break;
            }
        }
    }

    /**
     * @see IoFilterChain#addAfter(String, String, IoFilter)
     */
    public synchronized void addAfter(String baseName, String name,
            IoFilter filter) {
        checkBaseName(baseName);

        for (ListIterator<Entry> i = entries.listIterator(); i.hasNext();) {
            Entry base = i.next();
            if (base.getName().equals(baseName)) {
                register(i.nextIndex(), new EntryImpl(name, filter));
                break;
            }
        }
    }

    /**
     * @see IoFilterChain#remove(String)
     */
    public synchronized IoFilter remove(String name) {
        if (name == null) {
            throw new NullPointerException("name");
        }

        for (ListIterator<Entry> i = entries.listIterator(); i.hasNext();) {
            Entry e = i.next();
            if (e.getName().equals(name)) {
                entries.remove(i.previousIndex());
                return e.getFilter();
            }
        }

        throw new IllegalArgumentException("Unknown filter name: " + name);
    }

    /**
     * @see IoFilterChain#remove(IoFilter)
     */
    public synchronized IoFilter remove(IoFilter filter) {
        if (filter == null) {
            throw new NullPointerException("filter");
        }

        for (ListIterator<Entry> i = entries.listIterator(); i.hasNext();) {
            Entry e = i.next();
            if (e.getFilter() == filter) {
                entries.remove(i.previousIndex());
                return e.getFilter();
            }
        }

        throw new IllegalArgumentException("Filter not found: " + filter.getClass().getName());
    }

    /**
     * @see IoFilterChain#remove(Class)
     */
    public synchronized IoFilter remove(Class<? extends IoFilter> filterType) {
        if (filterType == null) {
            throw new NullPointerException("filterType");
        }

        for (ListIterator<Entry> i = entries.listIterator(); i.hasNext();) {
            Entry e = i.next();
            if (filterType.isAssignableFrom(e.getFilter().getClass())) {
                entries.remove(i.previousIndex());