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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.common;
21
22 import java.nio.channels.SelectionKey JavaDoc;
23
24 /**
25  * A type-safe mask that is used to control the traffic of {@link IoSession}
26  * with {@link IoSession#setTrafficMask(TrafficMask)}.
27  *
28  * @author The Apache Directory Project (mina-dev@directory.apache.org)
29  * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13 7월 2007) $
30  */
31 public class TrafficMask {
32     /**
33      * This mask suspends both reads and writes.
34      */
35     public static final TrafficMask NONE = new TrafficMask(0, "none");
36
37     /**
38      * This mask suspends writes, and resumes reads if reads were suspended.
39      */
40     public static final TrafficMask READ = new TrafficMask(
41             SelectionKey.OP_READ, "read");
42
43     /**
44      * This mask suspends reads, and resumes writes if writes were suspended.
45      */
46     public static final TrafficMask WRITE = new TrafficMask(
47             SelectionKey.OP_WRITE, "write");
48
49     /**
50      * This mask resumes both reads and writes if any of them were suspended.
51      */
52     public static final TrafficMask ALL = new TrafficMask(SelectionKey.OP_READ
53             | SelectionKey.OP_WRITE, "all");
54
55     /**
56      * Returns an appropriate {@link TrafficMask} instance from the
57      * specified <tt>interestOps</tt>.
58      * @see SelectionKey
59      */
60     public static TrafficMask getInstance(int interestOps) {
61         boolean read = (interestOps & SelectionKey.OP_READ) != 0;
62         boolean write = (interestOps & SelectionKey.OP_WRITE) != 0;
63         if (read) {
64             if (write) {
65                 return ALL;
66             } else {
67                 return READ;
68             }
69         } else if (write) {
70             return WRITE;
71         } else {
72             return NONE;
73         }
74     }
75
76     private final int interestOps;
77
78     private final String JavaDoc name;
79
80     private TrafficMask(int interestOps, String JavaDoc name) {
81         this.interestOps = interestOps;
82         this.name = name;
83     }
84
85     /**
86      * Returns the name of this mask.
87      */
88     public String JavaDoc getName() {
89         return name;
90     }
91
92     /**
93      * Returns <tt>true</tt> if this mask allows a read operation.
94      */
95     public boolean isReadable() {
96         return (interestOps & SelectionKey.OP_READ) != 0;
97     }
98
99     /**
100      * Returns <tt>true</tt> if this mask allows a write operation.
101      */
102     public boolean isWritable() {
103         return (interestOps & SelectionKey.OP_WRITE) != 0;
104     }
105
106     /**
107      * Returns an interestOps of {@link SelectionKey} for this mask.
108      */
109     public int getInterestOps() {
110         return interestOps;
111     }
112
113     /**
114      * Peforms an <tt>AND</tt> operation on this mask with the specified
115      * <tt>mask</tt> and returns the result.
116      */
117     public TrafficMask and(TrafficMask mask) {
118         return getInstance(interestOps & mask.interestOps);
119     }
120
121     /**
122      * Peforms an <tt>OR</tt> operation on this mask with the specified
123      * <tt>mask</tt> and returns the result.
124      */
125     public TrafficMask or(TrafficMask mask) {
126         return getInstance(interestOps | mask.interestOps);
127     }
128
129     /**
130      * Returns a negated mask of this one.
131      */
132     public TrafficMask not() {
133         return getInstance(~interestOps);
134     }
135
136     /**
137      * Peforms an <tt>XOR</tt> operation on this mask with the specified
138      * <tt>mask</tt> and returns the result.
139      */
140     public TrafficMask xor(TrafficMask mask) {
141         return getInstance(interestOps ^ mask.interestOps);
142     }
143
144     public String JavaDoc toString() {
145         return name;
146     }
147 }
148
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