1 /*
2 * $Source$
3 * $Revision$
4 *
5 * Copyright (C) 2000 William Chesters
6 *
7 * Part of Melati (http://melati.org), a framework for the rapid
8 * development of clean, maintainable web applications.
9 *
10 * Melati is free software; Permission is granted to copy, distribute
11 * and/or modify this software under the terms either:
12 *
13 * a) the GNU General Public License as published by the Free Software
14 * Foundation; either version 2 of the License, or (at your option)
15 * any later version,
16 *
17 * or
18 *
19 * b) any version of the Melati Software License, as published
20 * at http://melati.org
21 *
22 * You should have received a copy of the GNU General Public License and
23 * the Melati Software License along with this program;
24 * if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
26 * GNU General Public License and visit http://melati.org to obtain the
27 * Melati Software License.
28 *
29 * Feel free to contact the Developers of Melati (http://melati.org),
30 * if you would like to work out a different arrangement than the options
31 * outlined here. It is our intention to allow Melati to be used by as
32 * wide an audience as possible.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * Contact details for copyright holder:
40 *
41 * William Chesters <williamc At paneris.org>
42 * http://paneris.org/~williamc
43 * Obrechtstraat 114, 2517VX Den Haag, The Netherlands
44 */
45 package org.melati.util;
46
47 import java.io.PrintWriter;
48
49 /**
50 * A <code>PrintWriter</code> which can throw an <code>Exception</code>.
51 */
52 public final class ThrowingPrintWriter extends PrintWriter {
53 private PrintWriter pw;
54
55 /** Description of this PrintWriter. */
56 public final String description;
57
58 /**
59 * Thrown when a programmer attempts to use <code>super.out</code>.
60 */
61 public static class SuperUseException extends BugException {
62 private static final long serialVersionUID = 1L;
63 /**
64 * Constructor.
65 */
66 public SuperUseException() {
67 super("ThrowingPrintWriter tried to use super.out");
68 }
69 }
70
71 /**
72 * Constructor.
73 * @param pw Preint writer to write to
74 * @param description A description
75 */
76 public ThrowingPrintWriter(PrintWriter pw, String description) {
77 super(pw);
78 this.pw = pw;
79 this.description = description;
80 }
81
82 /**
83 * Thrown if there is a problem writing to this
84 * <code>ThowingPrintWriter</code>.
85 */
86 public class TroubleException extends MelatiRuntimeException {
87 private static final long serialVersionUID = 1L;
88 /**
89 * {@inheritDoc}
90 * @see org.melati.util.MelatiRuntimeException#getMessage()
91 */
92 public String getMessage() {
93 return "An exception condition occurred writing to " +
94 (description == null ? "a PrintWriter" : description);
95 }
96 }
97
98 /**
99 * Check for problem and throw it if found.
100 */
101 public void throwOnTrouble() {
102 if (pw.checkError())
103 throw new TroubleException();
104 }
105
106 /**
107 * Delegated method.
108 * {@inheritDoc}
109 * @see java.io.PrintWriter#flush()
110 */
111 public void flush() {
112 pw.flush();
113 throwOnTrouble();
114 }
115
116 /**
117 * Delegated method.
118 * {@inheritDoc}
119 * @see java.io.PrintWriter#close()
120 */
121 public void close() {
122 pw.close();
123 throwOnTrouble();
124 }
125
126 /**
127 * Delegated method.
128 * {@inheritDoc}
129 * @see java.io.PrintWriter#checkError()
130 */
131 public boolean checkError() {
132 return pw.checkError();
133 }
134
135 /**
136 * Delegated method.
137 * {@inheritDoc}
138 * @see java.io.PrintWriter#write(int)
139 */
140 public void write(int c) {
141 pw.write(c);
142 throwOnTrouble();
143 }
144
145 /**
146 * Delegated method.
147 * {@inheritDoc}
148 * @see java.io.PrintWriter#write(char[], int, int)
149 */
150 public void write(char buf[], int off, int len) {
151 pw.write(buf, off, len);
152 throwOnTrouble();
153 }
154
155 /**
156 * Delegated method.
157 * {@inheritDoc}
158 * @see java.io.PrintWriter#write(java.lang.String, int, int)
159 */
160 public void write(String buf, int off, int len) {
161 pw.write(buf, off, len);
162 throwOnTrouble();
163 }
164
165 /**
166 * Delegated method.
167 * {@inheritDoc}
168 * @see java.io.PrintWriter#println()
169 */
170 public void println() {
171 pw.println();
172 throwOnTrouble();
173 }
174 }