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Java > Open Source Codes > net > sf > clirr > core > FileDiffListener


1 //////////////////////////////////////////////////////////////////////////////
2 // Clirr: compares two versions of a java library for binary compatibility
3 // Copyright (C) 2003 - 2005 Lars Kühne
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 //////////////////////////////////////////////////////////////////////////////
19
20 package net.sf.clirr.core;
21
22 import java.io.FileNotFoundException JavaDoc;
23 import java.io.FileOutputStream JavaDoc;
24 import java.io.OutputStream JavaDoc;
25 import java.io.PrintStream JavaDoc;
26
27 /**
28  * Abstract DiffListener that writes output to some textual
29  * output stream. That stream can either be System.out or a textfile.
30  *
31  * @author lkuehne
32  */
33 abstract class FileDiffListener extends DiffListenerAdapter
34 {
35     private PrintStream JavaDoc outputStream;
36
37     /**
38      * Initializes the outputstream.
39      * @param outFile the filename (System.out is used if null is provided here)
40      * @throws java.io.FileNotFoundException if there are problems with
41      */
42     FileDiffListener(String JavaDoc outFile) throws FileNotFoundException JavaDoc
43     {
44         if (outFile == null)
45         {
46             outputStream = System.out;
47         }
48         else
49         {
50             final OutputStream JavaDoc out = new FileOutputStream JavaDoc(outFile);
51             outputStream = new PrintStream JavaDoc(out);
52         }
53
54     }
55
56     /**
57      * Returns the output stream so subclasses can write data.
58      * @return the output stream
59      */
60     protected final PrintStream JavaDoc getOutputStream()
61     {
62         return outputStream;
63     }
64
65
66     /**
67      * Writes a footer and closes the
68      * output stream if necessary.
69      *
70      * @see #writeFooter()
71      */
72     public final void stop()
73     {
74         writeFooter();
75
76         if (outputStream != System.out)
77         {
78             outputStream.close();
79         }
80         super.stop();
81     }
82
83     /**
84      * A hook to write footer info to the output stream.
85      * This implementation does nothing, subclasses can override
86      * this method if necessary.
87      *
88      * @see #stop()
89      */
90     protected void writeFooter()
91     {
92     }
93 }
94
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