001/*
002 * Copyright 2002-2015 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.servlet.tags;
018
019import javax.servlet.jsp.JspException;
020import javax.servlet.jsp.tagext.BodyTagSupport;
021
022/**
023 * JSP tag for collecting arguments and passing them to an {@link ArgumentAware}
024 * ancestor in the tag hierarchy.
025 *
026 * <p>This tag must be nested under an argument aware tag.
027 *
028 * @author Nicholas Williams
029 * @since 4.0
030 * @see MessageTag
031 * @see ThemeTag
032 */
033@SuppressWarnings("serial")
034public class ArgumentTag extends BodyTagSupport {
035
036        private Object value;
037
038        private boolean valueSet;
039
040
041        /**
042         * Set the value of the argument (optional).
043         * <pIf not set, the tag's body content will get evaluated.
044         * @param value the parameter value
045         */
046        public void setValue(Object value) {
047                this.value = value;
048                this.valueSet = true;
049        }
050
051
052        @Override
053        public int doEndTag() throws JspException {
054                Object argument = null;
055                if (this.valueSet) {
056                        argument = this.value;
057                }
058                else if (getBodyContent() != null) {
059                        // Get the value from the tag body
060                        argument = getBodyContent().getString().trim();
061                }
062
063                // Find a param-aware ancestor
064                ArgumentAware argumentAwareTag = (ArgumentAware) findAncestorWithClass(this, ArgumentAware.class);
065                if (argumentAwareTag == null) {
066                        throw new JspException("The argument tag must be a descendant of a tag that supports arguments");
067                }
068                argumentAwareTag.addArgument(argument);
069
070                return EVAL_PAGE;
071        }
072
073        @Override
074        public void release() {
075                super.release();
076                this.value = null;
077                this.valueSet = false;
078        }
079
080}