1 /**
2 * This file Copyright (c) 2003-2011 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.module.blossom.support;
35
36 import java.io.IOException;
37 import java.io.PrintWriter;
38 import java.io.Writer;
39 import javax.servlet.ServletResponse;
40
41 /**
42 * Writer that only opens the underlying writer when there is something needed to be written. This allows us to pass
43 * around a Writer instance without having acquired one from the servlet response.
44 *
45 * @since 0.5
46 */
47 public class LazyInitPrintWriter extends PrintWriter {
48
49 public LazyInitPrintWriter(final ServletResponse response) {
50 super(new Writer() {
51
52 private Writer writer;
53
54 @Override
55 public void write(char[] cbuf, int off, int len) throws IOException {
56 getTargetWriter().write(cbuf, off, len);
57 }
58
59 @Override
60 public void flush() throws IOException {
61 if (writer != null) {
62 writer.flush();
63 }
64 }
65
66 @Override
67 public void close() throws IOException {
68 getTargetWriter().close();
69 }
70
71 private Writer getTargetWriter() throws IOException {
72 if (writer != null) {
73 return writer;
74 }
75 writer = response.getWriter();
76 return writer;
77 }
78 });
79 }
80 }