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Java > Open Source Codes > org > apache > mina > filter > ReferenceCountingIoFilter


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one
3  * or more contributor license agreements. See the NOTICE file
4  * distributed with this work for additional information
5  * regarding copyright ownership. The ASF licenses this file
6  * to you under the Apache License, Version 2.0 (the
7  * "License"); you may not use this file except in compliance
8  * with the License. You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing,
13  * software distributed under the License is distributed on an
14  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15  * KIND, either express or implied. See the License for the
16  * specific language governing permissions and limitations
17  * under the License.
18  *
19  */
20 package org.apache.mina.filter;
21
22 import org.apache.mina.common.IdleStatus;
23 import org.apache.mina.common.IoFilter;
24 import org.apache.mina.common.IoFilterChain;
25 import org.apache.mina.common.IoSession;
26
27 /**
28  * An {@link IoFilter}s wrapper that keeps track of the number of usages of this filter and will call init/destroy
29  * when the filter is not in use.
30  *
31  * @author The Apache Directory Project (mina-dev@directory.apache.org)
32  * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13 7월 2007) $
33  */
34 public class ReferenceCountingIoFilter implements IoFilter {
35     private final IoFilter filter;
36
37     private int count = 0;
38
39     public ReferenceCountingIoFilter(IoFilter filter) {
40         this.filter = filter;
41     }
42
43     public void init() throws Exception JavaDoc {
44         // no-op, will init on-demand in pre-add if count == 0
45 }
46
47     public void destroy() throws Exception JavaDoc {
48         //no-op, will destroy on-demand in post-remove if count == 0
49 }
50
51     public synchronized void onPreAdd(IoFilterChain parent, String JavaDoc name,
52             NextFilter nextFilter) throws Exception JavaDoc {
53         if (0 == count) {
54             filter.init();
55
56             ++count;
57         }
58
59         filter.onPreAdd(parent, name, nextFilter);
60     }
61
62     public synchronized void onPostRemove(IoFilterChain parent, String JavaDoc name,
63             NextFilter nextFilter) throws Exception JavaDoc {
64         filter.onPostRemove(parent, name, nextFilter);
65
66         --count;
67
68         if (0 == count) {
69             filter.destroy();
70         }
71     }
72
73     public void exceptionCaught(NextFilter nextFilter, IoSession session,
74             Throwable JavaDoc cause) throws Exception JavaDoc {
75         filter.exceptionCaught(nextFilter, session, cause);
76     }
77
78     public void filterClose(NextFilter nextFilter, IoSession session)
79             throws Exception JavaDoc {
80         filter.filterClose(nextFilter, session);
81     }
82
83     public void filterWrite(NextFilter nextFilter, IoSession session,
84             WriteRequest writeRequest) throws Exception JavaDoc {
85         filter.filterWrite(nextFilter, session, writeRequest);
86     }
87
88     public void messageReceived(NextFilter nextFilter, IoSession session,
89             Object JavaDoc message) throws Exception JavaDoc {
90         filter.messageReceived(nextFilter, session, message);
91     }
92
93     public void messageSent(NextFilter nextFilter, IoSession session,
94             Object JavaDoc message) throws Exception JavaDoc {
95         filter.messageSent(nextFilter, session, message);
96     }
97
98     public void onPostAdd(IoFilterChain parent, String JavaDoc name,
99             NextFilter nextFilter) throws Exception JavaDoc {
100         filter.onPostAdd(parent, name, nextFilter);
101     }
102
103     public void onPreRemove(IoFilterChain parent, String JavaDoc name,
104             NextFilter nextFilter) throws Exception JavaDoc {
105         filter.onPreRemove(parent, name, nextFilter);
106     }
107
108     public void sessionClosed(NextFilter nextFilter, IoSession session)
109             throws Exception JavaDoc {
110         filter.sessionClosed(nextFilter, session);
111     }
112
113     public void sessionCreated(NextFilter nextFilter, IoSession session)
114             throws Exception JavaDoc {
115         filter.sessionCreated(nextFilter, session);
116     }
117
118     public void sessionIdle(NextFilter nextFilter, IoSession session,
119             IdleStatus status) throws Exception JavaDoc {
120         filter.sessionIdle(nextFilter, session, status);
121     }
122
123     public void sessionOpened(NextFilter nextFilter, IoSession session)
124             throws Exception JavaDoc {
125         filter.sessionOpened(nextFilter, session);
126     }
127 }
128
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