CascadingDataEntryWriter.java revision b72c5c2e5482cf10117b2b25f642f7616b2326c3 
1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu)
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the Free
9 * Software Foundation; either version 2 of the License, or (at your option)
10 * any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21package proguard.io;
22
23import java.io.*;
24
25/**
26 * This DataEntryWriter delegates to a given DataEntryWriter, or failing that,
27 * to another given DataEntryWriter.
28 *
29 * @author Eric Lafortune
30 */
31public class CascadingDataEntryWriter implements DataEntryWriter
32{
33    private DataEntryWriter dataEntryWriter1;
34    private DataEntryWriter dataEntryWriter2;
35
36
37    /**
38     * Creates a new CascadingDataEntryWriter.
39     * @param dataEntryWriter1 the DataEntryWriter to which the writing will be
40     *                         delegated first.
41     * @param dataEntryWriter2 the DataEntryWriter to which the writing will be
42     *                         delegated, if the first one can't provide an
43     *                         output stream.
44     */
45    public CascadingDataEntryWriter(DataEntryWriter dataEntryWriter1,
46                                    DataEntryWriter dataEntryWriter2)
47    {
48        this.dataEntryWriter1 = dataEntryWriter1;
49        this.dataEntryWriter2 = dataEntryWriter2;
50    }
51
52
53    // Implementations for DataEntryWriter.
54
55
56    public boolean createDirectory(DataEntry dataEntry) throws IOException
57    {
58        // Try to create a directory with the first data entry writer, or
59        // otherwise with the second data entry writer.
60        return dataEntryWriter1.createDirectory(dataEntry) ||
61               dataEntryWriter2.createDirectory(dataEntry);
62    }
63
64
65    public OutputStream getOutputStream(DataEntry dataEntry) throws IOException
66    {
67        return getOutputStream(dataEntry,  null);
68    }
69
70
71    public OutputStream getOutputStream(DataEntry dataEntry,
72                                        Finisher  finisher) throws IOException
73    {
74        // Try to get an output stream from the first data entry writer.
75        OutputStream outputStream =
76            dataEntryWriter1.getOutputStream(dataEntry, finisher);
77
78        // Return it, if it's not null. Otherwise try to get an output stream
79        // from the second data entry writer.
80        return outputStream != null ?
81            outputStream :
82            dataEntryWriter2.getOutputStream(dataEntry, finisher);
83    }
84
85
86    public void close() throws IOException
87    {
88        dataEntryWriter1.close();
89        dataEntryWriter2.close();
90
91        dataEntryWriter1 = null;
92        dataEntryWriter2 = null;
93    }
94}
95