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Jetty example source code file (TagAdapter.java)
The Jetty TagAdapter.java source code/** * * Copyright 2003-2004 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. */ // // This source code implements specifications defined by the Java // Community Process. In order to remain compliant with the specification // DO NOT add / change / or delete method signatures! // package javax.servlet.jsp.tagext; import javax.servlet.jsp.JspException; import javax.servlet.jsp.PageContext; /** * Wraps any SimpleTag and exposes it using a Tag interface. This is used * to allow collaboration between classic Tag handlers and SimpleTag * handlers. * <p> * Because SimpleTag does not extend Tag, and because Tag.setParent() * only accepts a Tag instance, a classic tag handler (one * that implements Tag) cannot have a SimpleTag as its parent. To remedy * this, a TagAdapter is created to wrap the SimpleTag parent, and the * adapter is passed to setParent() instead. A classic Tag EventHandler can * call getAdaptee() to retrieve the encapsulated SimpleTag instance. * * @since 2.0 */ public class TagAdapter implements Tag { /** The simple tag that's being adapted. */ private SimpleTag simpleTagAdaptee; /** The parent, of this tag, converted (if necessary) to be of type Tag. */ private Tag parent; // Flag indicating whether we have already determined the parent private boolean parentDetermined; /** * Creates a new TagAdapter that wraps the given SimpleTag and * returns the parent tag when getParent() is called. * * @param adaptee The SimpleTag being adapted as a Tag. */ public TagAdapter( SimpleTag adaptee ) { if( adaptee == null ) { // Cannot wrap a null adaptee. throw new IllegalArgumentException(); } this.simpleTagAdaptee = adaptee; } /** * Must not be called. * * @param pc ignored. * @throws UnsupportedOperationException Must not be called */ public void setPageContext(PageContext pc) { throw new UnsupportedOperationException( "Illegal to invoke setPageContext() on TagAdapter wrapper" ); } /** * Must not be called. The parent of this tag is always * getAdaptee().getParent(). * * @param parentTag ignored. * @throws UnsupportedOperationException Must not be called. */ public void setParent( Tag parentTag ) { throw new UnsupportedOperationException( "Illegal to invoke setParent() on TagAdapter wrapper" ); } /** * Returns the parent of this tag, which is always * getAdaptee().getParent(). * * This will either be the enclosing Tag (if getAdaptee().getParent() * implements Tag), or an adapter to the enclosing Tag (if * getAdaptee().getParent() does not implement Tag). * * @return The parent of the tag being adapted. */ public Tag getParent() { if (!parentDetermined) { JspTag adapteeParent = simpleTagAdaptee.getParent(); if (adapteeParent != null) { if (adapteeParent instanceof Tag) { this.parent = (Tag) adapteeParent; } else { // Must be SimpleTag - no other types defined. this.parent = new TagAdapter((SimpleTag) adapteeParent); } } parentDetermined = true; } return this.parent; } /** * Gets the tag that is being adapted to the Tag interface. * This should be an instance of SimpleTag in JSP 2.0, but room * is left for other kinds of tags in future spec versions. * * @return the tag that is being adapted */ public JspTag getAdaptee() { return this.simpleTagAdaptee; } /** * Must not be called. * * @return always throws UnsupportedOperationException * @throws UnsupportedOperationException Must not be called * @throws JspException never thrown */ public int doStartTag() throws JspException { throw new UnsupportedOperationException( "Illegal to invoke doStartTag() on TagAdapter wrapper" ); } /** * Must not be called. * * @return always throws UnsupportedOperationException * @throws UnsupportedOperationException Must not be called * @throws JspException never thrown */ public int doEndTag() throws JspException { throw new UnsupportedOperationException( "Illegal to invoke doEndTag() on TagAdapter wrapper" ); } /** * Must not be called. * * @throws UnsupportedOperationException Must not be called */ public void release() { throw new UnsupportedOperationException( "Illegal to invoke release() on TagAdapter wrapper" ); } } Other Jetty examples (source code examples)Here is a short list of links related to this Jetty TagAdapter.java source code file: |
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