1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. 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 package javax.servlet.jsp.tagext;
19
20 import java.util.Map;
21
22 /**
23 * Translation-time validator class for a JSP page.
24 * A validator operates on the XML view associated with the JSP page.
25 *
26 * <p>
27 * The TLD file associates a TagLibraryValidator class and some init
28 * arguments with a tag library.
29 *
30 * <p>
31 * The JSP container is reponsible for locating an appropriate
32 * instance of the appropriate subclass by
33 *
34 * <ul>
35 * <li> new a fresh instance, or reuse an available one
36 * <li> invoke the setInitParams(Map) method on the instance
37 * </ul>
38 *
39 * once initialized, the validate(String, String, PageData) method will
40 * be invoked, where the first two arguments are the prefix
41 * and uri for this tag library in the XML View. The prefix is intended
42 * to make it easier to produce an error message. However, it is not
43 * always accurate. In the case where a single URI is mapped to more
44 * than one prefix in the XML view, the prefix of the first URI is provided.
45 * Therefore, to provide high quality error messages in cases where the
46 * tag elements themselves are checked, the prefix parameter should be
47 * ignored and the actual prefix of the element should be used instead.
48 * TagLibraryValidators should always use the uri to identify elements
49 * as beloning to the tag library, not the prefix.
50 *
51 * <p>
52 * A TagLibraryValidator instance
53 * may create auxiliary objects internally to perform
54 * the validation (e.g. an XSchema validator) and may reuse it for all
55 * the pages in a given translation run.
56 *
57 * <p>
58 * The JSP container is not guaranteed to serialize invocations of
59 * validate() method, and TagLibraryValidators should perform any
60 * synchronization they may require.
61 *
62 * <p>
63 * As of JSP 2.0, a JSP container must provide a jsp:id attribute to
64 * provide higher quality validation errors.
65 * The container will track the JSP pages
66 * as passed to the container, and will assign to each element
67 * a unique "id", which is passed as the value of the jsp:id
68 * attribute. Each XML element in the XML view available will
69 * be extended with this attribute. The TagLibraryValidator
70 * can then use the attribute in one or more ValidationMessage
71 * objects. The container then, in turn, can use these
72 * values to provide more precise information on the location
73 * of an error.
74 *
75 * <p>
76 * The actual prefix of the <code>id</code> attribute may or may not be
77 * <code>jsp</code> but it will always map to the namespace
78 * <code>http://java.sun.com/JSP/Page</code>. A TagLibraryValidator
79 * implementation must rely on the uri, not the prefix, of the <code>id</code>
80 * attribute.
81 */
82
83 abstract public class TagLibraryValidator {
84
85 /**
86 * Sole constructor. (For invocation by subclass constructors,
87 * typically implicit.)
88 */
89 public TagLibraryValidator() {
90 }
91
92 /**
93 * Set the init data in the TLD for this validator.
94 * Parameter names are keys, and parameter values are the values.
95 *
96 * @param map A Map describing the init parameters
97 */
98 public void setInitParameters(Map<String, Object> map) {
99 initParameters = map;
100 }
101
102
103 /**
104 * Get the init parameters data as an immutable Map.
105 * Parameter names are keys, and parameter values are the values.
106 *
107 * @return The init parameters as an immutable map.
108 */
109 public Map<String, Object> getInitParameters() {
110 return initParameters;
111 }
112
113 /**
114 * Validate a JSP page.
115 * This will get invoked once per unique tag library URI in the
116 * XML view. This method will return null if the page is valid; otherwise
117 * the method should return an array of ValidationMessage objects.
118 * An array of length zero is also interpreted as no errors.
119 *
120 * @param prefix the first prefix with which the tag library is
121 * associated, in the XML view. Note that some tags may use
122 * a different prefix if the namespace is redefined.
123 * @param uri the tag library's unique identifier
124 * @param page the JspData page object
125 * @return A null object, or zero length array if no errors, an array
126 * of ValidationMessages otherwise.
127 */
128 public ValidationMessage[] validate(String prefix, String uri,
129 PageData page)
130 {
131 return null;
132 }
133
134 /**
135 * Release any data kept by this instance for validation purposes.
136 */
137 public void release() {
138 initParameters = null;
139 }
140
141 // Private data
142 private Map<String, Object> initParameters;
143
144 }