1 /*
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6 * Portions Copyright Apache Software Foundation.
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37 */
38
39 package javax.servlet.jsp.tagext;
40
41 import java.util.Map;
42
43 /**
44 * Translation-time validator class for a JSP page.
45 * A validator operates on the XML view associated with the JSP page.
46 *
47 * <p>
48 * The TLD file associates a TagLibraryValidator class and some init
49 * arguments with a tag library.
50 *
51 * <p>
52 * The JSP container is reponsible for locating an appropriate
53 * instance of the appropriate subclass by
54 *
55 * <ul>
56 * <li> new a fresh instance, or reuse an available one
57 * <li> invoke the setInitParams(Map) method on the instance
58 * </ul>
59 *
60 * once initialized, the validate(String, String, PageData) method will
61 * be invoked, where the first two arguments are the prefix
62 * and uri for this tag library in the XML View. The prefix is intended
63 * to make it easier to produce an error message. However, it is not
64 * always accurate. In the case where a single URI is mapped to more
65 * than one prefix in the XML view, the prefix of the first URI is provided.
66 * Therefore, to provide high quality error messages in cases where the
67 * tag elements themselves are checked, the prefix parameter should be
68 * ignored and the actual prefix of the element should be used instead.
69 * TagLibraryValidators should always use the uri to identify elements
70 * as beloning to the tag library, not the prefix.
71 *
72 * <p>
73 * A TagLibraryValidator instance
74 * may create auxiliary objects internally to perform
75 * the validation (e.g. an XSchema validator) and may reuse it for all
76 * the pages in a given translation run.
77 *
78 * <p>
79 * The JSP container is not guaranteed to serialize invocations of
80 * validate() method, and TagLibraryValidators should perform any
81 * synchronization they may require.
82 *
83 * <p>
84 * As of JSP 2.0, a JSP container must provide a jsp:id attribute to
85 * provide higher quality validation errors.
86 * The container will track the JSP pages
87 * as passed to the container, and will assign to each element
88 * a unique "id", which is passed as the value of the jsp:id
89 * attribute. Each XML element in the XML view available will
90 * be extended with this attribute. The TagLibraryValidator
91 * can then use the attribute in one or more ValidationMessage
92 * objects. The container then, in turn, can use these
93 * values to provide more precise information on the location
94 * of an error.
95 *
96 * <p>
97 * The actual prefix of the <code>id</code> attribute may or may not be
98 * <code>jsp</code> but it will always map to the namespace
99 * <code>http://java.sun.com/JSP/Page</code>. A TagLibraryValidator
100 * implementation must rely on the uri, not the prefix, of the <code>id</code>
101 * attribute.
102 */
103
104 abstract public class TagLibraryValidator {
105
106 /**
107 * Sole constructor. (For invocation by subclass constructors,
108 * typically implicit.)
109 */
110 public TagLibraryValidator() {
111 }
112
113 /**
114 * Set the init data in the TLD for this validator.
115 * Parameter names are keys, and parameter values are the values.
116 *
117 * @param map A Map describing the init parameters
118 */
119 public void setInitParameters(Map map) {
120 initParameters = map;
121 }
122
123
124 /**
125 * Get the init parameters data as an immutable Map.
126 * Parameter names are keys, and parameter values are the values.
127 *
128 * @return The init parameters as an immutable map.
129 */
130 public Map getInitParameters() {
131 return initParameters;
132 }
133
134 /**
135 * Validate a JSP page.
136 * This will get invoked once per unique tag library URI in the
137 * XML view. This method will return null if the page is valid; otherwise
138 * the method should return an array of ValidationMessage objects.
139 * An array of length zero is also interpreted as no errors.
140 *
141 * @param prefix the first prefix with which the tag library is
142 * associated, in the XML view. Note that some tags may use
143 * a different prefix if the namespace is redefined.
144 * @param uri the tag library's unique identifier
145 * @param page the JspData page object
146 * @return A null object, or zero length array if no errors, an array
147 * of ValidationMessages otherwise.
148 */
149 public ValidationMessage[] validate(String prefix, String uri,
150 PageData page)
151 {
152 return null;
153 }
154
155 /**
156 * Release any data kept by this instance for validation purposes.
157 */
158 public void release() {
159 initParameters = null;
160 }
161
162 // Private data
163 private Map initParameters;
164
165 }
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