/* * $Header: /home/cvs/jakarta-taglibs/i18n/src/org/apache/taglibs/i18n/MessageTag.java,v 1.5 2002/12/17 04:18:59 glenn Exp $ * $Revision: 1.5 $ * $Date: 2002/12/17 04:18:59 $ * * ==================================================================== * * 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 * . * */ package org.apache.taglibs.i18n; import java.io.IOException; import java.text.MessageFormat; import java.util.Arrays; import java.util.ArrayList; import java.util.List; import java.util.Locale; import java.util.ResourceBundle; import javax.servlet.ServletContext; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspTagException; import javax.servlet.jsp.PageContext; import javax.servlet.jsp.tagext.BodyTag; import javax.servlet.jsp.tagext.BodyTagSupport; /** * This class implements a body tag that allows you to use a resource bundle * to internationalize content in a web page. The "key" attribute is required, * and is used to look up content in the resource bundle. The "args" attribute * is optional, and if present, provides items to pass to a MessageFormat. * * The BundleTag must first be used in order to ensure that the proper bundle * is loaded. *

*

Examples

*
 *  <i18n:bundle baseName="test"/>
 *  <i18n:getMessage key="test"/>
 *  <i18n:getMessage key="test" args="1,2,3"/>
 *  etc...
 *  
*

* * @author Tim Dawson * */ public class MessageTag extends BodyTagSupport { // instance variables used during processing private String _key = null; private String _value = null; private ResourceBundle _bundle = null; private String _bundleRef = null; private Object [] _args = null; private boolean _debug = false; // these are reused for each message tag; luckily tags are thread-safe private MessageFormat _messageFormat = new MessageFormat(""); private List _arguments = new ArrayList(); /** * sets the key to use when looking up the value in the bundle */ public final void setKey(String key) { _key = key; } /** * sets the bundle based on a variable defined in the page
* if neither bundle or bundleRef are specified, uses the first bundle * defined on the page by the i18n:bundle tag */ public final void setBundleRef(String varName) { _bundleRef = varName; } /** * sets the bundle to an actual ResourceBundle object
* if neither bundle or bundleRef are specified, uses the bundle most recently * defined on the page by the i18n:bundle tag */ public final void setBundle(ResourceBundle aBundle) { _bundle = aBundle; } /** * @return the bundle to use */ private ResourceBundle getBundle() throws JspException { ResourceBundle bundle = _bundle; if ( bundle == null ) { if ( _bundleRef != null ) { bundle = (ResourceBundle)pageContext.getAttribute(_bundleRef); if ( bundle == null ) { throw new JspTagException( "i18n:message tag, could not find bundleRef=" + _bundleRef); } } else { BundleTag bundleTag = (BundleTag)this.findAncestorWithClass(this,BundleTag.class); if (bundleTag != null) { return bundleTag.getBundle(); } bundle = ResourceHelper.getBundle(pageContext); } } return bundle; } /** * Turn debugging log messages on or off */ public final void setDebug(boolean value) { _debug = value; } /** * adds to the list of arguments used when formatting the message */ protected final void addArg(Object arg) { _arguments.add(arg); if (_debug) { ServletContext sc = pageContext.getServletContext(); sc.log("i18n:message added arg: " + arg.toString()); } } /** * allows setting all the arguments at once */ public final void setArgs(Object[] args) { _args = args; } /** * clears the argument list so that sub tags can call addArgument * clears out any previous key and value in case key is not provided, * or the value is null */ public final void release() { super.release(); _arguments.clear(); _key = null; _value = null; _bundle = null; } /** * locates the bundle and gets the value */ public final int doStartTag() throws JspException { // Reset value for resource bundle key _value = null; // ensure we have a key if ( _key == null ) { throw new JspTagException("i18n:message tag requires a key attribute."); } ResourceBundle bundle = this.getBundle(); if ( bundle == null ) { throw new JspTagException( "i18n:message tag, no bundle available for use."); } // Reset the arguments _arguments.clear(); if ( _args != null ) { _arguments.addAll(Arrays.asList(_args)); } // see if the bundle has a value, if not, we default to the tag contents try { _value = bundle.getString(_key); if (_debug) { ServletContext sc = pageContext.getServletContext(); sc.log("i18n:message tag: template for " + _key + " is: " + _value); } } catch (java.util.MissingResourceException e) { ServletContext sc = pageContext.getServletContext(); sc.log("i18n:message tag, value not found for key:" + _key); } return EVAL_BODY_TAG; } /** * Performs the proper runtime substitution. If an id attribute was * specified, then it is assumed that this tag is merely defining a * string variable; otherwise output is provided. */ public final int doEndTag() throws JspException { try { // if the value is null, use the body content if ( _value == null ) { _value = bodyContent.getString(); bodyContent.clear(); } // perform parameter substitutions if ( _value != null && _arguments != null && _arguments.size() > 0) { // reformat the value as specified _messageFormat.setLocale(this.getBundle().getLocale()); _messageFormat.applyPattern(_value); _value = _messageFormat.format(_arguments.toArray()); } if ( _value == null) { if (_debug) { ServletContext sc = pageContext.getServletContext(); sc.log("i18n: message: skipping null value for " + _key); } } else if (id != null) { // define the variable in the page context pageContext.setAttribute(id,_value); } else { // print the value to the JspWriter this.pageContext.getOut().print(_value); } } catch (java.io.IOException e) { throw new JspTagException("i18n:message tag IO Error: " + e.getMessage()); } // only process the body once return EVAL_PAGE; } }