KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > opensymphony > module > sitemesh > filter > RoutablePrintWriter


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 JavaDoc;
7 import java.io.IOException JavaDoc;
8 import java.io.Writer JavaDoc;
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 JavaDoc {
19
20     private PrintWriter JavaDoc destination;
21     private DestinationFactory factory;
22
23     /**
24      * Factory to lazily instantiate the destination.
25      */
26     public static interface DestinationFactory {
27         PrintWriter JavaDoc activateDestination() throws IOException JavaDoc;
28     }
29
30     public RoutablePrintWriter(DestinationFactory factory) {
31         super(new NullWriter());
32         this.factory = factory;
33     }
34
35     private PrintWriter JavaDoc getDestination() {
36         if (destination == null) {
37             try {
38                 destination = factory.activateDestination();
39             } catch (IOException JavaDoc 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 JavaDoc x) {
56         getDestination().println(x);
57     }
58
59     public void println(String JavaDoc 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 JavaDoc obj) {
96         getDestination().print(obj);
97     }
98
99     public void print(String JavaDoc 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 JavaDoc s) {
132         getDestination().write(s);
133     }
134
135     public void write(String JavaDoc 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 JavaDoc {
163
164         protected NullWriter() {
165             super();
166         }
167
168         public void write(char cbuf[], int off, int len) throws IOException JavaDoc {
169             throw new UnsupportedOperationException JavaDoc();
170         }
171
172         public void flush() throws IOException JavaDoc {
173             throw new UnsupportedOperationException JavaDoc();
174         }
175
176         public void close() throws IOException JavaDoc {
177             throw new UnsupportedOperationException JavaDoc();
178         }
179
180     }
181
182 }
183
Popular Tags