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; import java.io.Reader; import java.io.Writer; import java.io.IOException; import javax.servlet.jsp.*; /** * An encapsulation of the evaluation of the body of an action so it is * available to a tag handler. BodyContent is a subclass of JspWriter. * * <p> * Note that the content of BodyContent is the result of evaluation, so * it will not contain actions and the like, but the result of their * invocation. * * <p> * BodyContent has methods to convert its contents into * a String, to read its contents, and to clear the contents. * * <p> * The buffer size of a BodyContent object is unbounded. A * BodyContent object cannot be in autoFlush mode. It is not possible to * invoke flush on a BodyContent object, as there is no backing stream. * * <p> * Instances of BodyContent are created by invoking the pushBody and * popBody methods of the PageContext class. A BodyContent is enclosed * within another JspWriter (maybe another BodyContent object) following * the structure of their associated actions. * * <p> * A BodyContent is made available to a BodyTag through a setBodyContent() * call. The tag handler can use the object until after the call to * doEndTag(). */ public abstract class BodyContent extends JspWriter { /** * Protected constructor. * * Unbounded buffer, no autoflushing. * * @param e the enclosing JspWriter */ protected BodyContent(JspWriter e) { super(UNBOUNDED_BUFFER, false); this.enclosingWriter = e; } /** * Redefined flush() so it is not legal. * * <p> * It is not valid to flush a BodyContent because there is no backing * stream behind it. * * @throws IOException always thrown */ public void flush() throws IOException { throw new IOException("Illegal to flush within a custom tag"); } /** * Clear the body without throwing any exceptions. */ public void clearBody() { try { this.clear(); } catch (IOException ex) { // TODO -- clean this one up. throw new Error("internal error!;"); } } /** * Return the value of this BodyContent as a Reader. * * @return the value of this BodyContent as a Reader */ public abstract Reader getReader(); /** * Return the value of the BodyContent as a String. * * @return the value of the BodyContent as a String */ public abstract String getString(); /** * Write the contents of this BodyContent into a Writer. * Subclasses may optimize common invocation patterns. * * @param out The writer into which to place the contents of * this body evaluation * @throws IOException if an I/O error occurred while writing the * contents of this BodyContent to the given Writer */ public abstract void writeOut(Writer out) throws IOException; /** * Get the enclosing JspWriter. * * @return the enclosing JspWriter passed at construction time */ public JspWriter getEnclosingWriter() { return enclosingWriter; } // private fields private JspWriter enclosingWriter; }