Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html * or packager/legal/LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at packager/legal/LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. * * * This file incorporates work covered by the following copyright and * permission notice: * * Copyright 2004 The Apache Software Foundation * * Licensed 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 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package javax.servlet.jsp.tagext; /** * Optional class provided by the tag library author to describe additional * translation-time information not described in the TLD. * The TagExtraInfo class is mentioned in the Tag Library Descriptor file (TLD). * * <p> * This class can be used: * <ul> * <li> to indicate that the tag defines scripting variables * <li> to perform translation-time validation of the tag attributes. * </ul> * * <p> * It is the responsibility of the JSP translator that the initial value * to be returned by calls to getTagInfo() corresponds to a TagInfo * object for the tag being translated. If an explicit call to * setTagInfo() is done, then the object passed will be returned in * subsequent calls to getTagInfo(). * * <p> * The only way to affect the value returned by getTagInfo() * is through a setTagInfo() call, and thus, TagExtraInfo.setTagInfo() is * to be called by the JSP translator, with a TagInfo object that * corresponds to the tag being translated. The call should happen before * any invocation on validate() and before any invocation on * getVariableInfo(). * * <p> * <tt>NOTE:</tt> It is a (translation time) error for a tag definition * in a TLD with one or more variable subelements to have an associated * TagExtraInfo implementation that returns a VariableInfo array with * one or more elements from a call to getVariableInfo(). */ public abstract class TagExtraInfo { /** * Sole constructor. (For invocation by subclass constructors, * typically implicit.) */ public TagExtraInfo() { } /** * information on scripting variables defined by the tag associated with * this TagExtraInfo instance. * Request-time attributes are indicated as such in the TagData parameter. * * @param data The TagData instance. * @return An array of VariableInfo data, or null or a zero length array * if no scripting variables are to be defined. */ public VariableInfo[] getVariableInfo(TagData data) { return ZERO_VARIABLE_INFO; } /** * Translation-time validation of the attributes. * Request-time attributes are indicated as such in the TagData parameter. * Note that the preferred way to do validation is with the validate() * method, since it can return more detailed information. * * @param data The TagData instance. * @return Whether this tag instance is valid. * @see TagExtraInfo#validate */ public boolean isValid(TagData data) { return true; } /** * Translation-time validation of the attributes. * Request-time attributes are indicated as such in the TagData parameter. * Because of the higher quality validation messages possible, * this is the preferred way to do validation (although isValid() * still works). * * <p>JSP 2.0 and higher containers call validate() instead of isValid(). * The default implementation of this method is to call isValid(). If * isValid() returns false, a generic ValidationMessage[] is returned * indicating isValid() returned false.</p> * * @param data The TagData instance. * @return A null object, or zero length array if no errors, an * array of ValidationMessages otherwise. * @since JSP 2.0 */ public ValidationMessage[] validate(TagData data) { ValidationMessage[] result = null; if (!isValid(data)) { result = new ValidationMessage[] { new ValidationMessage(data.getId(), "isValid() == false") }; } return result; } /** * Set the TagInfo for this class. * * @param tagInfo The TagInfo this instance is extending */ public final void setTagInfo(TagInfo tagInfo) { this.tagInfo = tagInfo; } /** * Get the TagInfo for this class. * * @return the taginfo instance this instance is extending */ public final TagInfo getTagInfo() { return tagInfo; } // private data private TagInfo tagInfo; // zero length VariableInfo array private static final VariableInfo[] ZERO_VARIABLE_INFO = {}; }