Source code: com/microstar/xml/HandlerBase.java
1 // HandlerBase.java: Simple base class for AElfred processors.
2 // NO WARRANTY! See README, and copyright below.
3 // $Id: HandlerBase.java,v 1.1.1.1 2001/08/20 22:31:22 gfx Exp $
4
5 package com.microstar.xml;
6
7 import com.microstar.xml.XmlHandler;
8 import com.microstar.xml.XmlException;
9 import java.io.Reader;
10
11
12 /**
13 * Convenience base class for AElfred handlers.
14 * <p>This base class implements the XmlHandler interface with
15 * (mostly empty) default handlers. You are not required to use this,
16 * but if you need to handle only a few events, you might find
17 * it convenient to extend this class rather than implementing
18 * the entire interface. This example overrides only the
19 * <code>charData</code> method, using the defaults for the others:
20 * <pre>
21 * import com.microstar.xml.HandlerBase;
22 *
23 * public class MyHandler extends HandlerBase {
24 * public void charData (char ch[], int start, int length)
25 * {
26 * System.out.println("Data: " + new String (ch, start, length));
27 * }
28 * }
29 * </pre>
30 * <p>This class is optional, but if you use it, you must also
31 * include the <code>XmlException</code> class.
32 * <p>Do not extend this if you are using SAX; extend
33 * <code>org.xml.sax.HandlerBase</code> instead.
34 * @author Copyright (c) 1998 by Microstar Software Ltd.
35 * @author written by David Megginson <dmeggins@microstar.com>
36 * @version 1.1
37 * @see XmlHandler
38 * @see XmlException
39 * @see org.xml.sax.HandlerBase
40 */
41 public class HandlerBase implements XmlHandler {
42
43 /**
44 * Handle the start of the document.
45 * <p>The default implementation does nothing.
46 * @see com.microstar.xml.XmlHandler#startDocument
47 * @exception java.lang.Exception Derived methods may throw exceptions.
48 */
49 public void startDocument ()
50 throws java.lang.Exception
51 {
52 }
53
54 /**
55 * Handle the end of the document.
56 * <p>The default implementation does nothing.
57 * @see com.microstar.xml.XmlHandler#endDocument
58 * @exception java.lang.Exception Derived methods may throw exceptions.
59 */
60 public void endDocument ()
61 throws java.lang.Exception
62 {
63 }
64
65 /**
66 * Resolve an external entity.
67 * <p>The default implementation simply returns the supplied
68 * system identifier.
69 * @see com.microstar.xml.XmlHandler#resolveEntity
70 * @exception java.lang.Exception Derived methods may throw exceptions.
71 */
72 public Object resolveEntity (String publicId, String systemId)
73 throws java.lang.Exception
74 {
75 return null;
76 }
77
78
79 /**
80 * Handle the start of an external entity.
81 * <p>The default implementation does nothing.
82 * @see com.microstar.xml.XmlHandler#startExternalEntity
83 * @exception java.lang.Exception Derived methods may throw exceptions.
84 */
85 public void startExternalEntity (String systemId)
86 throws java.lang.Exception
87 {
88 }
89
90 /**
91 * Handle the end of an external entity.
92 * <p>The default implementation does nothing.
93 * @see com.microstar.xml.XmlHandler#endExternalEntity
94 * @exception java.lang.Exception Derived methods may throw exceptions.
95 */
96 public void endExternalEntity (String systemId)
97 throws java.lang.Exception
98 {
99 }
100
101 /**
102 * Handle a document type declaration.
103 * <p>The default implementation does nothing.
104 * @see com.microstar.xml.XmlHandler#doctypeDecl
105 * @exception java.lang.Exception Derived methods may throw exceptions.
106 */
107 public void doctypeDecl (String name, String publicId, String systemId)
108 throws java.lang.Exception
109 {
110 }
111
112 /**
113 * Handle an attribute assignment.
114 * <p>The default implementation does nothing.
115 * @see com.microstar.xml.XmlHandler#attribute
116 * @exception java.lang.Exception Derived methods may throw exceptions.
117 */
118 public void attribute (String aname, String value, boolean isSpecified)
119 throws java.lang.Exception
120 {
121 }
122
123 /**
124 * Handle the start of an element.
125 * <p>The default implementation does nothing.
126 * @see com.microstar.xml.XmlHandler#startElement
127 * @exception java.lang.Exception Derived methods may throw exceptions.
128 */
129 public void startElement (String elname)
130 throws java.lang.Exception
131 {
132 }
133
134 /**
135 * Handle the end of an element.
136 * <p>The default implementation does nothing.
137 * @see com.microstar.xml.XmlHandler#endElement
138 * @exception java.lang.Exception Derived methods may throw exceptions.
139 */
140 public void endElement (String elname)
141 throws java.lang.Exception
142 {
143 }
144
145 /**
146 * Handle character data.
147 * <p>The default implementation does nothing.
148 * @see com.microstar.xml.XmlHandler#charData
149 * @exception java.lang.Exception Derived methods may throw exceptions.
150 */
151 public void charData (char ch[], int start, int length)
152 throws java.lang.Exception
153 {
154 }
155
156 /**
157 * Handle ignorable whitespace.
158 * <p>The default implementation does nothing.
159 * @see com.microstar.xml.XmlHandler#ignorableWhitespace
160 * @exception java.lang.Exception Derived methods may throw exceptions.
161 */
162 public void ignorableWhitespace (char ch[], int start, int length)
163 throws java.lang.Exception
164 {
165 }
166
167 /**
168 * Handle a processing instruction.
169 * <p>The default implementation does nothing.
170 * @see com.microstar.xml.XmlHandler#processingInstruction
171 * @exception java.lang.Exception Derived methods may throw exceptions.
172 */
173 public void processingInstruction (String target, String data)
174 throws java.lang.Exception
175 {
176 }
177
178 /**
179 * Throw an exception for a fatal error.
180 * <p>The default implementation throws <code>XmlException</code>.
181 * @see com.microstar.xml.XmlHandler#error
182 * @exception com.microstar.xml.XmlException A specific parsing error.
183 * @exception java.lang.Exception Derived methods may throw exceptions.
184 */
185 public void error (String message, String systemId, int line, int column)
186 throws XmlException, java.lang.Exception
187 {
188 throw new XmlException(message, systemId, line, column);
189 }
190
191 }