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.statemachine.transition;
21
22 import org.apache.commons.lang.builder.EqualsBuilder;
23 import org.apache.commons.lang.builder.HashCodeBuilder;
24 import org.apache.commons.lang.builder.ToStringBuilder;
25 import org.apache.mina.statemachine.State;
26 import org.apache.mina.statemachine.StateMachine;
27 import org.apache.mina.statemachine.event.Event;
28
29 /**
30 * Abstract {@link Transition} implementation. Takes care of matching the
31 * current {@link Event}'s id against the id of the {@link Event} this
32 * {@link Transition} handles. To handle any {@link Event} the id should be set
33 * to {@link Event#WILDCARD_EVENT_ID}.
34 *
35 * @author The Apache MINA Project (dev@mina.apache.org)
36 * @version $Rev: 586695 $, $Date: 2007-10-20 12:01:17 +0200 (sam, 20 oct 2007) $
37 */
38 public abstract class AbstractTransition implements Transition {
39 private final Object eventId;
40
41 private final State nextState;
42
43 /**
44 * Creates a new instance which will loopback to the same {@link State}
45 * for the specified {@link Event} id.
46 *
47 * @param eventId the {@link Event} id.
48 */
49 public AbstractTransition(Object eventId) {
50 this(eventId, null);
51 }
52
53 /**
54 * Creates a new instance with the specified {@link State} as next state
55 * and for the specified {@link Event} id.
56 *
57 * @param eventId the {@link Event} id.
58 * @param nextState the next {@link State}.
59 */
60 public AbstractTransition(Object eventId, State nextState) {
61 this.eventId = eventId;
62 this.nextState = nextState;
63 }
64
65 public State getNextState() {
66 return nextState;
67 }
68
69 public boolean execute(Event event) {
70 if (!eventId.equals(Event.WILDCARD_EVENT_ID) && !eventId.equals(event.getId())) {
71 return false;
72 }
73
74 return doExecute(event);
75 }
76
77 /**
78 * Executes this {@link Transition}. This method doesn't have to check
79 * if the {@link Event}'s id matches because {@link #execute(Event)} has
80 * already made sure that that is the case.
81 *
82 * @param event the current {@link Event}.
83 * @return <code>true</code> if the {@link Transition} has been executed
84 * successfully and the {@link StateMachine} should move to the
85 * next {@link State}. <code>false</code> otherwise.
86 */
87 protected abstract boolean doExecute(Event event);
88
89 public boolean equals(Object o) {
90 if (!(o instanceof AbstractTransition)) {
91 return false;
92 }
93 if (o == this) {
94 return true;
95 }
96 AbstractTransition that = (AbstractTransition) o;
97 return new EqualsBuilder()
98 .append(eventId, that.eventId)
99 .append(nextState, that.nextState)
100 .isEquals();
101 }
102
103 public int hashCode() {
104 return new HashCodeBuilder(11, 31).append(eventId).append(nextState).toHashCode();
105 }
106
107 public String toString() {
108 return new ToStringBuilder(this)
109 .append("eventId", eventId)
110 .append("nextState", nextState)
111 .toString();
112 }
113 }