001: /*
002: * Licensed to the Apache Software Foundation (ASF) under one or more
003: * contributor license agreements. See the NOTICE file distributed with
004: * this work for additional information regarding copyright ownership.
005: * The ASF licenses this file to You under the Apache License, Version 2.0
006: * (the "License"); you may not use this file except in compliance with
007: * the License. You may obtain a copy of the License at
008: *
009: * http://www.apache.org/licenses/LICENSE-2.0
010: *
011: * Unless required by applicable law or agreed to in writing, software
012: * distributed under the License is distributed on an "AS IS" BASIS,
013: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014: * See the License for the specific language governing permissions and
015: * limitations under the License.
016: */
017:
018: package javax.servlet.jsp.tagext;
019:
020: import java.util.Map;
021:
022: /**
023: * Translation-time validator class for a JSP page.
024: * A validator operates on the XML view associated with the JSP page.
025: *
026: * <p>
027: * The TLD file associates a TagLibraryValidator class and some init
028: * arguments with a tag library.
029: *
030: * <p>
031: * The JSP container is reponsible for locating an appropriate
032: * instance of the appropriate subclass by
033: *
034: * <ul>
035: * <li> new a fresh instance, or reuse an available one
036: * <li> invoke the setInitParams(Map) method on the instance
037: * </ul>
038: *
039: * once initialized, the validate(String, String, PageData) method will
040: * be invoked, where the first two arguments are the prefix
041: * and uri for this tag library in the XML View. The prefix is intended
042: * to make it easier to produce an error message. However, it is not
043: * always accurate. In the case where a single URI is mapped to more
044: * than one prefix in the XML view, the prefix of the first URI is provided.
045: * Therefore, to provide high quality error messages in cases where the
046: * tag elements themselves are checked, the prefix parameter should be
047: * ignored and the actual prefix of the element should be used instead.
048: * TagLibraryValidators should always use the uri to identify elements
049: * as beloning to the tag library, not the prefix.
050: *
051: * <p>
052: * A TagLibraryValidator instance
053: * may create auxiliary objects internally to perform
054: * the validation (e.g. an XSchema validator) and may reuse it for all
055: * the pages in a given translation run.
056: *
057: * <p>
058: * The JSP container is not guaranteed to serialize invocations of
059: * validate() method, and TagLibraryValidators should perform any
060: * synchronization they may require.
061: *
062: * <p>
063: * As of JSP 2.0, a JSP container must provide a jsp:id attribute to
064: * provide higher quality validation errors.
065: * The container will track the JSP pages
066: * as passed to the container, and will assign to each element
067: * a unique "id", which is passed as the value of the jsp:id
068: * attribute. Each XML element in the XML view available will
069: * be extended with this attribute. The TagLibraryValidator
070: * can then use the attribute in one or more ValidationMessage
071: * objects. The container then, in turn, can use these
072: * values to provide more precise information on the location
073: * of an error.
074: *
075: * <p>
076: * The actual prefix of the <code>id</code> attribute may or may not be
077: * <code>jsp</code> but it will always map to the namespace
078: * <code>http://java.sun.com/JSP/Page</code>. A TagLibraryValidator
079: * implementation must rely on the uri, not the prefix, of the <code>id</code>
080: * attribute.
081: */
082:
083: abstract public class TagLibraryValidator {
084:
085: /**
086: * Sole constructor. (For invocation by subclass constructors,
087: * typically implicit.)
088: */
089: public TagLibraryValidator() {
090: }
091:
092: /**
093: * Set the init data in the TLD for this validator.
094: * Parameter names are keys, and parameter values are the values.
095: *
096: * @param map A Map describing the init parameters
097: */
098: public void setInitParameters(Map<String, Object> map) {
099: initParameters = map;
100: }
101:
102: /**
103: * Get the init parameters data as an immutable Map.
104: * Parameter names are keys, and parameter values are the values.
105: *
106: * @return The init parameters as an immutable map.
107: */
108: public Map<String, Object> getInitParameters() {
109: return initParameters;
110: }
111:
112: /**
113: * Validate a JSP page.
114: * This will get invoked once per unique tag library URI in the
115: * XML view. This method will return null if the page is valid; otherwise
116: * the method should return an array of ValidationMessage objects.
117: * An array of length zero is also interpreted as no errors.
118: *
119: * @param prefix the first prefix with which the tag library is
120: * associated, in the XML view. Note that some tags may use
121: * a different prefix if the namespace is redefined.
122: * @param uri the tag library's unique identifier
123: * @param page the JspData page object
124: * @return A null object, or zero length array if no errors, an array
125: * of ValidationMessages otherwise.
126: */
127: public ValidationMessage[] validate(String prefix, String uri,
128: PageData page) {
129: return null;
130: }
131:
132: /**
133: * Release any data kept by this instance for validation purposes.
134: */
135: public void release() {
136: initParameters = null;
137: }
138:
139: // Private data
140: private Map<String, Object> initParameters;
141:
142: }
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