setlocalesupport.java

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/*
 * Copyright 1999-2004 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 org.apache.taglibs.standard.tag.common.fmt;

import java.text.DateFormat;
import java.text.NumberFormat;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Vector;

import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.jstl.core.Config;
import javax.servlet.jsp.jstl.fmt.LocalizationContext;
import javax.servlet.jsp.tagext.Tag;
import javax.servlet.jsp.tagext.TagSupport;

import org.apache.taglibs.standard.resources.Resources;
import org.apache.taglibs.standard.tag.common.core.Util;

/**
 * Support for tag handlers for <setLocale>, the locale setting tag in
 * JSTL 1.0.
 *
 * @author Jan Luehe
 */

public abstract class SetLocaleSupport extends TagSupport {

    
    //*********************************************************************
    // Private constants

    private static final char HYPHEN = '-';
    private static final char UNDERSCORE = '_';


    //*********************************************************************
    // Protected state

    protected Object value;                      // 'value' attribute
    protected String variant;                    // 'variant' attribute


    //*********************************************************************
    // Private state

    private int scope;                           // 'scope' attribute


    //*********************************************************************
    // Constructor and initialization

    public SetLocaleSupport() {
	super();
	init();
    }

    private void init() {
	value = variant = null;
	scope = PageContext.PAGE_SCOPE;
    }


   //*********************************************************************
    // Tag attributes known at translation time

    public void setScope(String scope) {
	this.scope = Util.getScope(scope);
    }


    //*********************************************************************
    // Tag logic

    public int doEndTag() throws JspException {
	Locale locale = null;

	if (value == null) {
	    locale = Locale.getDefault();
	} else if (value instanceof String) {
	    if (((String) value).trim().equals("")) {
		locale = Locale.getDefault();
	    } else {
		locale = parseLocale((String) value, variant);
	    }
	} else {
	    locale = (Locale) value;
	}

	Config.set(pageContext, Config.FMT_LOCALE, locale, scope);
	setResponseLocale(pageContext, locale);

	return EVAL_PAGE;
    }

    // Releases any resources we may have (or inherit)
    public void release() {
	init();
    }


    //*********************************************************************
    // Public utility methods

    /**
     * See parseLocale(String, String) for details.
     */
    public static Locale parseLocale(String locale) {
	return parseLocale(locale, null);
    }

    /**
     * Parses the given locale string into its language and (optionally)
     * country components, and returns the corresponding
     * <tt>java.util.Locale</tt> object.
     *
     * If the given locale string is null or empty, the runtime's default
     * locale is returned.
     *
     * @param locale the locale string to parse
     * @param variant the variant
     *
     * @return <tt>java.util.Locale</tt> object corresponding to the given
     * locale string, or the runtime's default locale if the locale string is
     * null or empty
     *
     * @throws IllegalArgumentException if the given locale does not have a
     * language component or has an empty country component
     */
    public static Locale parseLocale(String locale, String variant) {

	Locale ret = null;
	String language = locale;
	String country = null;
	int index = -1;

	if (((index = locale.indexOf(HYPHEN)) > -1)
	        || ((index = locale.indexOf(UNDERSCORE)) > -1)) {
	    language = locale.substring(0, index);
	    country = locale.substring(index+1);
	}

	if ((language == null) || (language.length() == 0)) {
	    throw new IllegalArgumentException(
		Resources.getMessage("LOCALE_NO_LANGUAGE"));
	}

	if (country == null) {
	    if (variant != null)
		ret = new Locale(language, "", variant);
	    else
		ret = new Locale(language, "");
	} else if (country.length() > 0) {
	    if (variant != null)
		ret = new Locale(language, country, variant);
	    else
		ret = new Locale(language, country);
	} else {
	    throw new IllegalArgumentException(
		Resources.getMessage("LOCALE_EMPTY_COUNTRY"));
	}

	return ret;
    }


    //*********************************************************************
    // Package-scoped utility methods

    /*
     * Stores the given locale in the response object of the given page
     * context, and stores the locale's associated charset in the
     * javax.servlet.jsp.jstl.fmt.request.charset session attribute, which
     * may be used by the <requestEncoding> action in a page invoked by a
     * form included in the response to set the request charset to the same as
     * the response charset (this makes it possible for the container to
     * decode the form parameter values properly, since browsers typically
     * encode form field values using the response's charset).
     *
     * @param pageContext the page context whose response object is assigned
     * the given locale
     * @param locale the response locale
     */
    static void setResponseLocale(PageContext pc, Locale locale) {
	// set response locale
	ServletResponse response = pc.getResponse();
	response.setLocale(locale);
	
	// get response character encoding and store it in session attribute
	if (pc.getSession() != null) {
            try {
	        pc.setAttribute(RequestEncodingSupport.REQUEST_CHAR_SET,
			    response.getCharacterEncoding(),
			    PageContext.SESSION_SCOPE);
            } catch (IllegalStateException ex) {} // invalidated session ignored
	}
    }
 
    /*
     * Returns the formatting locale to use with the given formatting action
     * in the given page.
     *
     * @param pc The page context containing the formatting action
     * @param fromTag The formatting action
     * @param format <tt>true</tt> if the formatting action is of type
     * <formatXXX> (as opposed to <parseXXX>), and <tt>false</tt> otherwise
     * (if set to <tt>true</tt>, the formatting locale that is returned by
     * this method is used to set the response locale).
     *
     * @param avail the array of available locales
     *
     * @return the formatting locale to use
     */
    static Locale getFormattingLocale(PageContext pc,
				      Tag fromTag,