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1 /* This software is published under the terms of the OpenSymphony Software
2 * License version 1.1, of which a copy has been included with this
3 * distribution in the LICENSE.txt file. */
4 package com.opensymphony.module.sitemesh.filter;
5
6 import java.io.PrintWriter;
7 import java.io.IOException;
8 import java.io.Writer;
9
10 /**
11 * Provides a PrintWriter that routes through to another PrintWriter, however the destination
12 * can be changed at any point. The destination can be passed in using a factory, so it will not be created
13 * until it's actually needed.
14 *
15 * @author Joe Walnes
16 * @version $Revision: 1.1 $
17 */
18 public class RoutablePrintWriter extends PrintWriter {
19
20 private PrintWriter destination;
21 private DestinationFactory factory;
22
23 /**
24 * Factory to lazily instantiate the destination.
25 */
26 public static interface DestinationFactory {
27 PrintWriter activateDestination() throws IOException;
28 }
29
30 public RoutablePrintWriter(DestinationFactory factory) {
31 super(new NullWriter());
32 this.factory = factory;
33 }
34
35 private PrintWriter getDestination() {
36 if (destination == null) {
37 try {
38 destination = factory.activateDestination();
39 } catch (IOException e) {
40 setError();
41 }
42 }
43 return destination;
44 }
45
46 public void updateDestination(DestinationFactory factory) {
47 destination = null;
48 this.factory = factory;
49 }
50
51 public void close() {
52 getDestination().close();
53 }
54
55 public void println(Object x) {
56 getDestination().println(x);
57 }
58
59 public void println(String x) {
60 getDestination().println(x);
61 }
62
63 public void println(char x[]) {
64 getDestination().println(x);
65 }
66
67 public void println(double x) {
68 getDestination().println(x);
69 }
70
71 public void println(float x) {
72 getDestination().println(x);
73 }
74
75 public void println(long x) {
76 getDestination().println(x);
77 }
78
79 public void println(int x) {
80 getDestination().println(x);
81 }
82
83 public void println(char x) {
84 getDestination().println(x);
85 }
86
87 public void println(boolean x) {
88 getDestination().println(x);
89 }
90
91 public void println() {
92 getDestination().println();
93 }
94
95 public void print(Object obj) {
96 getDestination().print(obj);
97 }
98
99 public void print(String s) {
100 getDestination().print(s);
101 }
102
103 public void print(char s[]) {
104 getDestination().print(s);
105 }
106
107 public void print(double d) {
108 getDestination().print(d);
109 }
110
111 public void print(float f) {
112 getDestination().print(f);
113 }
114
115 public void print(long l) {
116 getDestination().print(l);
117 }
118
119 public void print(int i) {
120 getDestination().print(i);
121 }
122
123 public void print(char c) {
124 getDestination().print(c);
125 }
126
127 public void print(boolean b) {
128 getDestination().print(b);
129 }
130
131 public void write(String s) {
132 getDestination().write(s);
133 }
134
135 public void write(String s, int off, int len) {
136 getDestination().write(s, off, len);
137 }
138
139 public void write(char buf[]) {
140 getDestination().write(buf);
141 }
142
143 public void write(char buf[], int off, int len) {
144 getDestination().write(buf, off, len);
145 }
146
147 public void write(int c) {
148 getDestination().write(c);
149 }
150
151 public boolean checkError() {
152 return getDestination().checkError();
153 }
154
155 public void flush() {
156 getDestination().flush();
157 }
158
159 /**
160 * Just to keep super constructor for PrintWriter happy - it's never actually used.
161 */
162 private static class NullWriter extends Writer {
163
164 protected NullWriter() {
165 super();
166 }
167
168 public void write(char cbuf[], int off, int len) throws IOException {
169 throw new UnsupportedOperationException();
170 }
171
172 public void flush() throws IOException {
173 throw new UnsupportedOperationException();
174 }
175
176 public void close() throws IOException {
177 throw new UnsupportedOperationException();
178 }
179
180 }
181
182 }