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Java > Open Source Codes > Jt > examples > patterns > Timer


1 package Jt.examples.patterns;
2
3 import Jt.*;
4 import java.io.*;
5 import java.util.*;
6 import Jt.xml.*;
7
8
9 /**
10  * Timer implementation based on the Command pattern. The timer runs in a separate
11  * Thread.
12  */
13
14
15 public class Timer extends JtCommand {
16
17   private long tstart; // t0
18 private long tend; // t1
19 private double time; // Elapsed time in seconds (delta)
20
21   public Timer() {
22     this.setSynchronous (false); // asyncronous processing (separate thread)
23 }
24
25  
26   // Attributes
27
28   public double getTime () {
29      return (time);
30   }
31
32
33   public void setTime (double time) {
34      this.time = time;
35   }
36
37   // Process object messages
38
39   public Object JavaDoc processMessage (Object JavaDoc message) {
40
41    String JavaDoc msgid = null;
42    JtMessage msg = (JtMessage) message;
43    Object JavaDoc content;
44
45      if (msg == null)
46     return null;
47
48      msgid = (String JavaDoc) msg.getMsgId ();
49
50      if (msgid == null)
51     return null;
52
53      content = msg.getMsgContent();
54
55      // Start timer
56
57      if (msgid.equals ("START_TIMER")) {
58
59         tstart = (new Date()).getTime ();
60
61         // Log the message
62 logMessage (msg);
63         sendMessage (this, new JtMessage ("CHECK_TIMER"));
64         return (null);
65      }
66
67      // Check the timer
68
69      if (msgid.equals ("CHECK_TIMER")) {
70
71         tend = (new Date ()).getTime ();
72         time = (tend - tstart)/1000.0;
73         System.out.println ("Timer:" + time);
74              
75         // Add another CHECK_TIMER request to the queue of messages
76
77         sendMessage (this, new JtMessage ("CHECK_TIMER"));
78
79         return (null);
80      }
81
82      // Stop the timer
83
84      if (msgid.equals ("STOP_TIMER")) {
85
86         tend = (new Date ()).getTime ();
87         time = (tend - tstart)/1000.0;
88         sendMessage (this, new JtMessage ("JtSTOP"));
89             
90         // Log the message
91 logMessage (msg);
92         return (null);
93      }
94
95
96      // Let the superclass handle JtSTART, JtREMOVE and JtSTOP
97
98      if (msgid.equals ("JtREMOVE") || msgid.equals ("JtSTART") || msgid.equals ("JtSTOP")) {
99         return (super.processMessage (message));
100      }
101          
102      handleError ("Timer.processMessage: invalid message id:" + msgid);
103      return (null);
104
105   }
106
107   static private char waitForInputKey () {
108     char c = ' ';
109
110       try {
111
112       c = (char) System.in.read ();
113       while (System.in.available () > 0)
114         System.in.read ();
115
116       } catch (Exception JavaDoc e) {
117         e.printStackTrace ();
118       }
119
120       return (c);
121   }
122
123   // Test program
124
125   public static void main(String JavaDoc[] args) {
126
127     JtObject main = new JtFactory ();
128     JtMessage msg, msg1;
129     JtXMLHelper xmlHelper = new JtXMLHelper ();
130    
131
132
133
134     // Create the timer
135
136     main.createObject ("Jt.examples.patterns.Timer", "timer");
137
138     System.out.println ("Press any key to start/stop the timer ....");
139     waitForInputKey ();
140
141     // Send a message to start the timer (separate/independent thread)
142
143     main.sendMessage ("timer", new JtMessage ("START_TIMER"));
144
145
146     //System.out.println ("Press any key to stop the timer ....");
147 waitForInputKey ();
148
149
150     main.sendMessage ("timer", new JtMessage ("STOP_TIMER"));
151
152     System.out.println (main.getValue ("timer", "time") + " second(s) elapsed");
153
154     // Remove object
155
156     main.removeObject ("timer");
157
158   }
159
160 }
161
162
163
164
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