TagSupport.java
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上传日期:2022-07-20
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文件大小:7k
源码类别:
数据库编程
开发平台:
Java
- /*
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 1999 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution, if
- * any, must include the following acknowlegement:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowlegement may appear in the software itself,
- * if and wherever such third-party acknowlegements normally appear.
- *
- * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
- * Foundation" must not be used to endorse or promote products derived
- * from this software without prior written permission. For written
- * permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache"
- * nor may "Apache" appear in their names without prior written
- * permission of the Apache Group.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- *
- */
- package javax.servlet.jsp.tagext;
- import javax.servlet.jsp.*;
- import javax.servlet.jsp.tagext.*;
- import javax.servlet.*;
- import java.io.Writer;
- import java.io.Serializable;
- import java.util.Hashtable;
- import java.util.Enumeration;
- /**
- * Actions in a Tag Library are defined through subclasses of Tag.
- */
- public class TagSupport implements Tag, Serializable {
- /**
- * Find the instance of a given class type that is closest to a given
- * instance.
- * This class is used for coordination among cooperating tags.
- *
- * @param the subclass of Tag or interface to be matched
- * @return the nearest ancestor that implements the interface
- * or is an instance of the class specified
- */
- public static final Tag findAncestorWithClass(Tag from, Class klass) {
- boolean isInterface = false;
- if (from == null ||
- klass == null ||
- (!Tag.class.isAssignableFrom(klass) &&
- !(isInterface = klass.isInterface()))) {
- return null;
- }
- for (;;) {
- Tag tag = from.getParent();
- if (tag == null) {
- return null;
- }
- if ((isInterface && klass.isInstance(tag)) ||
- klass.isAssignableFrom(tag.getClass()))
- return tag;
- else
- from = tag;
- }
- }
- /**
- * Default constructor, all subclasses are required to only define
- * a public constructor with the same signature, and to call the
- * superclass constructor.
- *
- * This constructor is called by the code generated by the JSP
- * translator.
- *
- * @param libraryPrefix The namespace prefix used for this library.
- * For example "jsp:".
- * @param tagName The name of the element or yag, for example "useBean"
- */
- public TagSupport() { }
- /**
- * doStartTag(), doEndTag() are most basic.
- * setBodyOut(), doBeforeBody(), and doAfterBody() deal with body
- *
- * In many cases not all of them are redefined.
- */
- // Actions for basic start/end processing.
- /**
- * Process the start tag for this instance.
- *
- * The doStartTag() method assumes that all setter methods have been
- * invoked before.
- *
- * When this method is invoked, the body has not yet been invoked.
- *
- * @returns EVAL_BODY_INCLUDE if the tag wants to process body, SKIP_BODY if it
- * does ont want to process it.
- */
- public int doStartTag() throws JspException {
- return SKIP_BODY;
- }
- /**
- * Process the end tag. This method will be called on all Tag objects.
- *
- * All instance state associated with this instance must be reset.
- */
- public int doEndTag() throws JspException {
- return EVAL_PAGE;
- }
- /**
- * release() called after doEndTag() to reset state
- */
- public void release() {
- parent = null;
- }
- /**
- * Methods to access state
- */
- /**
- * Set the nesting tag of this tag.
- */
- public void setParent(Tag t) {
- parent = t;
- }
- /**
- * The Tag instance enclosing this tag instance.
- *
- * @return the parent tag instance or null
- */
- public Tag getParent() {
- return parent;
- }
- /**
- * Set the id attribute
- */
- public void setId(String id) {
- this.id = id;
- }
- /**
- * The value of the id attribute of this tag; or null.
- *
- * @return the value of the id attribute, or null
- */
- public String getId() {
- return id;
- }
- /**
- * set the page context
- */
- public void setPageContext(PageContext pageContext) {
- this.pageContext = pageContext;
- }
- /**
- * Set a value
- */
- public void setValue(String k, Object o) {
- if (values == null) {
- values = new Hashtable();
- }
- values.put(k, o);
- }
- /**
- * Get a value
- */
- public Object getValue(String k) {
- if (values == null) {
- return null;
- } else {
- return values.get(k);
- }
- }
- /**
- * Remove a value
- */
- public void removeValue(String k) {
- if (values != null) {
- values.remove(k);
- }
- }
- /**
- * Enumerate the values
- */
- public Enumeration getValues() {
- if (values == null) {
- return null;
- }
- return values.keys();
- }
- // private fields
- private Tag parent;
- private Hashtable values;
- protected String id;
- // protected fields
- protected PageContext pageContext;
- }