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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
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package javax.servlet.jsp.tagext;

import java.util.Map;

/**
 * Translation-time validator class for a JSP page.
 * A validator operates on the XML view associated with the JSP page.
 *
 * 

* The TLD file associates a TagLibraryValidator class and some init * arguments with a tag library. * *

* The JSP container is responsible for locating an appropriate * instance of the appropriate subclass by * *

    *
  • new a fresh instance, or reuse an available one *
  • invoke the setInitParams(Map) method on the instance *
* * once initialized, the validate(String, String, PageData) method will * be invoked, where the first two arguments are the prefix * and uri for this tag library in the XML View. The prefix is intended * to make it easier to produce an error message. However, it is not * always accurate. In the case where a single URI is mapped to more * than one prefix in the XML view, the prefix of the first URI is provided. * Therefore, to provide high quality error messages in cases where the * tag elements themselves are checked, the prefix parameter should be * ignored and the actual prefix of the element should be used instead. * TagLibraryValidators should always use the uri to identify elements * as belonging to the tag library, not the prefix. * *

* A TagLibraryValidator instance * may create auxiliary objects internally to perform * the validation (e.g. an XSchema validator) and may reuse it for all * the pages in a given translation run. * *

* The JSP container is not guaranteed to serialize invocations of * validate() method, and TagLibraryValidators should perform any * synchronization they may require. * *

* As of JSP 2.0, a JSP container must provide a jsp:id attribute to * provide higher quality validation errors. * The container will track the JSP pages * as passed to the container, and will assign to each element * a unique "id", which is passed as the value of the jsp:id * attribute. Each XML element in the XML view available will * be extended with this attribute. The TagLibraryValidator * can then use the attribute in one or more ValidationMessage * objects. The container then, in turn, can use these * values to provide more precise information on the location * of an error. * *

* The actual prefix of the id attribute may or may not be * jsp but it will always map to the namespace * http://java.sun.com/JSP/Page. A TagLibraryValidator * implementation must rely on the uri, not the prefix, of the id * attribute. */ public abstract class TagLibraryValidator { /** * Sole constructor. (For invocation by subclass constructors, * typically implicit.) */ public TagLibraryValidator() { // NOOP by default } /** * Set the init data in the TLD for this validator. * Parameter names are keys, and parameter values are the values. * * @param map A Map describing the init parameters */ public void setInitParameters(Map map) { initParameters = map; } /** * Get the init parameters data as an immutable Map. * Parameter names are keys, and parameter values are the values. * * @return The init parameters as an immutable map. */ public Map getInitParameters() { return initParameters; } /** * Validate a JSP page. * This will get invoked once per unique tag library URI in the * XML view. This method will return null if the page is valid; otherwise * the method should return an array of ValidationMessage objects. * An array of length zero is also interpreted as no errors. * * @param prefix the first prefix with which the tag library is * associated, in the XML view. Note that some tags may use * a different prefix if the namespace is redefined. * @param uri the tag library's unique identifier * @param page the JspData page object * @return A null object, or zero length array if no errors, an array * of ValidationMessages otherwise. */ public ValidationMessage[] validate(String prefix, String uri, PageData page) { return null; } /** * Release any data kept by this instance for validation purposes. */ public void release() { initParameters = null; } // Private data private Map initParameters; }





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