1 /**
2 *
3 * Copyright 2003-2004 The Apache Software Foundation
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 //
19 // This source code implements specifications defined by the Java
20 // Community Process. In order to remain compliant with the specification
21 // DO NOT add / change / or delete method signatures!
22 //
23
24 package javax.servlet.jsp.tagext;
25
26 import java.util.Map;
27
28 /**
29 * Translation-time validator class for a JSP page.
30 * A validator operates on the XML view associated with the JSP page.
31 *
32 * <p>
33 * The TLD file associates a TagLibraryValidator class and some init
34 * arguments with a tag library.
35 *
36 * <p>
37 * The JSP container is reponsible for locating an appropriate
38 * instance of the appropriate subclass by
39 *
40 * <ul>
41 * <li> new a fresh instance, or reuse an available one
42 * <li> invoke the setInitParams(Map) method on the instance
43 * </ul>
44 *
45 * once initialized, the validate(String, String, PageData) method will
46 * be invoked, where the first two arguments are the prefix
47 * and uri for this tag library in the XML View. The prefix is intended
48 * to make it easier to produce an error message. However, it is not
49 * always accurate. In the case where a single URI is mapped to more
50 * than one prefix in the XML view, the prefix of the first URI is provided.
51 * Therefore, to provide high quality error messages in cases where the
52 * tag elements themselves are checked, the prefix parameter should be
53 * ignored and the actual prefix of the element should be used instead.
54 * TagLibraryValidators should always use the uri to identify elements
55 * as beloning to the tag library, not the prefix.
56 *
57 * <p>
58 * A TagLibraryValidator instance
59 * may create auxiliary objects internally to perform
60 * the validation (e.g. an XSchema validator) and may reuse it for all
61 * the pages in a given translation run.
62 *
63 * <p>
64 * The JSP container is not guaranteed to serialize invocations of
65 * validate() method, and TagLibraryValidators should perform any
66 * synchronization they may require.
67 *
68 * <p>
69 * As of JSP 2.0, a JSP container must provide a jsp:id attribute to
70 * provide higher quality validation errors.
71 * The container will track the JSP pages
72 * as passed to the container, and will assign to each element
73 * a unique "id", which is passed as the value of the jsp:id
74 * attribute. Each XML element in the XML view available will
75 * be extended with this attribute. The TagLibraryValidator
76 * can then use the attribute in one or more ValidationMessage
77 * objects. The container then, in turn, can use these
78 * values to provide more precise information on the location
79 * of an error.
80 *
81 * <p>
82 * The actual prefix of the <code>id</code> attribute may or may not be
83 * <code>jsp</code> but it will always map to the namespace
84 * <code>http://java.sun.com/JSP/Page</code>. A TagLibraryValidator
85 * implementation must rely on the uri, not the prefix, of the <code>id</code>
86 * attribute.
87 */
88
89 abstract public class TagLibraryValidator {
90
91 /**
92 * Sole constructor. (For invocation by subclass constructors,
93 * typically implicit.)
94 */
95 public TagLibraryValidator() {
96 }
97
98 /**
99 * Set the init data in the TLD for this validator.
100 * Parameter names are keys, and parameter values are the values.
101 *
102 * @param map A Map describing the init parameters
103 */
104 public void setInitParameters(Map map) {
105 initParameters = map;
106 }
107
108
109 /**
110 * Get the init parameters data as an immutable Map.
111 * Parameter names are keys, and parameter values are the values.
112 *
113 * @return The init parameters as an immutable map.
114 */
115 public Map getInitParameters() {
116 return initParameters;
117 }
118
119 /**
120 * Validate a JSP page.
121 * This will get invoked once per unique tag library URI in the
122 * XML view. This method will return null if the page is valid; otherwise
123 * the method should return an array of ValidationMessage objects.
124 * An array of length zero is also interpreted as no errors.
125 *
126 * @param prefix the first prefix with which the tag library is
127 * associated, in the XML view. Note that some tags may use
128 * a different prefix if the namespace is redefined.
129 * @param uri the tag library's unique identifier
130 * @param page the JspData page object
131 * @return A null object, or zero length array if no errors, an array
132 * of ValidationMessages otherwise.
133 */
134 public ValidationMessage[] validate(String prefix, String uri,
135 PageData page)
136 {
137 return null;
138 }
139
140 /**
141 * Release any data kept by this instance for validation purposes.
142 */
143 public void release() {
144 initParameters = null;
145 }
146
147 // Private data
148 private Map initParameters;
149
150 }