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Java > Open Source Codes > nu > xom > xinclude > XIncludeException


1 /* Copyright 2002-2005 Elliotte Rusty Harold
2    
3    This library is free software; you can redistribute it and/or modify
4    it under the terms of version 2.1 of the GNU Lesser General Public
5    License as published by the Free Software Foundation.
6    
7    This library is distributed in the hope that it will be useful,
8    but WITHOUT ANY WARRANTY; without even the implied warranty of
9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10    GNU Lesser General Public License for more details.
11    
12    You should have received a copy of the GNU Lesser General Public
13    License along with this library; if not, write to the
14    Free Software Foundation, Inc., 59 Temple Place, Suite 330,
15    Boston, MA 02111-1307 USA
16    
17    You can contact Elliotte Rusty Harold by sending e-mail to
18    elharo@metalab.unc.edu. Please include the word "XOM" in the
19    subject line. The XOM home page is located at http://www.xom.nu/
20 */
21
22 package nu.xom.xinclude;
23
24 /**
25  * <p>
26  * The generic superclass for all checked exceptions that may be thrown
27  * as a result of a violation of XInclude's rules.
28  * </p>
29  *
30  * @author Elliotte Rusty Harold
31  * @version 1.0
32  */
33 public class XIncludeException extends Exception JavaDoc {
34
35     
36     private String JavaDoc uri;
37
38     /**
39      * <p>
40      * Constructs an <code>XIncludeException</code> with the specified
41      * detail message.
42      * </p>
43      *
44      * @param message a string indicating the specific problem
45      */
46     public XIncludeException(String JavaDoc message) {
47         super(message);
48     }
49
50     
51     /**
52      * <p>
53      * Constructs an <code>XIncludeException</code> with the specified
54      * detail message and initial cause. The error message string
55      * <code>message</code> can later be retrieved by the
56      * <code>{@link java.lang.Throwable#getMessage}</code>
57      * method of class <code>java.lang.Throwable</code>.
58      * </p>
59      *
60      * @param message a string indicating the specific problem
61      * @param cause the initial cause of the exception
62      */
63     public XIncludeException(String JavaDoc message, Throwable JavaDoc cause) {
64         super(message);
65         initCause(cause);
66     }
67
68     
69     /**
70      * <p>
71      * Creates a new <code>XIncludeException</code> with a detail
72      * message, line and column numbers, and the URI of the document
73      * that caused the exception.
74      * </p>
75      *
76      * @param message a string indicating the specific problem
77      * @param uri the URI of the document that caused this exception
78      */
79     public XIncludeException(String JavaDoc message, String JavaDoc uri) {
80         super(message);
81         this.uri = uri;
82     }
83
84     
85     /**
86      * <p>
87      * Returns the URI of the document that caused this exception.
88      * If the URI is not known, null is returned.
89      * </p>
90      *
91      * @return URI of the document where the exception occurred
92      */
93     public String JavaDoc getURI() {
94         return this.uri;
95     }
96
97     
98     private Throwable JavaDoc cause;
99
100     
101     /**
102      * <p>
103      * When an <code>IOException</code>,
104      * <code>MalformedURLException</code>, or other generic
105      * exception is thrown while processing an XML document
106      * for XIncludes, it is customarily replaced
107      * by some form of <code>XIncludeException</code>.
108      * This method allows you to retrieve the original exception.
109      * It returns null if no such exception caused this
110      * <code>XIncludeException</code>.
111      *</p>
112      *
113      * @return the underlying exception which
114      * caused this XIncludeException to be thrown
115      */
116     public Throwable JavaDoc getCause() {
117         return this.cause;
118     }
119
120     
121     // null is insufficient for detecting an uninitialized cause.
122 // The cause may be set to null which may not then be reset.
123 private boolean causeSet = false;
124
125     
126     /**
127      * <p>
128      * When an <code>IOException</code>,
129      * <code>MalformedURLException</code>, or other generic exception
130      * is thrown while processing an XML document
131      * for XIncludes, it is customarily replaced
132      * by some form of <code>XIncludeException</code>.
133      * This method allows you to store the original exception.
134      * </p>
135      *
136      * @param cause the root cause of this exception
137      *
138      * @return this <code>XIncludeException</code>
139      *
140      * @throws IllegalArgumentException if the cause is this exception
141      * (An exception cannot be its own cause.)
142      * @throws IllegalStateException if this method is called twice
143      */
144     public Throwable JavaDoc initCause(Throwable JavaDoc cause) {
145         if (causeSet) {
146             throw new IllegalStateException JavaDoc("Can't overwrite cause");
147         }
148         else if (cause == this) {
149             throw new IllegalArgumentException JavaDoc("Self-causation not permitted");
150         }
151         else this.cause = cause;
152         causeSet = true;
153         return this;
154     }
155
156     
157 }
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