javax.faces.view.facelets.TagHandler Maven / Gradle / Ivy
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/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
* Copyright 2005-2007 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.faces.view.facelets;
/**
* Foundation class for
* FaceletHandlers associated with a markup element in a
* Facelet document. This class introduces the concept of XML attributes to Facelets. See the constructor
* documentation for more details.
*
*
* @since 2.0
*/
public abstract class TagHandler implements FaceletHandler {
/**
* See {@link TagConfig#getTagId}.
*/
protected final String tagId;
/**
* A reference to the Tag
* instance corresponding to this TagHandler
* instance.
*/
protected final Tag tag;
/**
* A reference to the
* FaceletHandler that represents the first nested
* child of this TagHandler instance.
*/
protected final FaceletHandler nextHandler;
/**
* Every TagHandler
* instance is associated with a {@link Tag}. Each Tag
* instance has a {@link TagAttributes} property, which is simply a
* collection of {@link TagAttribute} instances. Extract and save
* as protected instance variables the {@link TagConfig#getTagId},
* {@link TagConfig#getTag} and {@link TagConfig#getNextHandler}
* returns from the argument TagConfig. This
* constructor is only called when the Facelets View is compiled.
*
*
* @param config The structure that contains useful to the operation
* of this instance.
*/
public TagHandler(TagConfig config) {
this.tagId = config.getTagId();
this.tag = config.getTag();
this.nextHandler = config.getNextHandler();
}
/**
* Utility method for fetching the appropriate TagAttribute
*
* @param localName
* name of attribute
* @return TagAttribute if found, otherwise null
*/
protected final TagAttribute getAttribute(String localName) {
return this.tag.getAttributes().get(localName);
}
/**
* Utility method for fetching a required TagAttribute
*
* @param localName
* name of the attribute
* @return TagAttribute if found, otherwise error
* @throws TagException
* if the attribute was not found
*/
protected final TagAttribute getRequiredAttribute(String localName)
throws TagException {
TagAttribute attr = this.getAttribute(localName);
if (attr == null) {
throw new TagException(this.tag, "Attribute '" + localName
+ "' is required");
}
return attr;
}
public String toString() {
return this.tag.toString();
}
}