Util.java

/*
 * 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.anodyneos.xp.tag;

import java.text.DateFormat;
import java.util.Enumeration;

import javax.servlet.http.HttpServletRequest;

import org.anodyneos.xp.XpException;

/**
 * <p>
 * Utilities in support of tag-handler classes.
 * </p>
 *
 * @author Jan Luehe
 */
public class Util {

    private static final String DEFAULT = "default";
    private static final String SHORT = "short";
    private static final String MEDIUM = "medium";
    private static final String LONG = "long";
    private static final String FULL = "full";

    /*
     * Converts the given string description of a formatting style for dates and
     * times to the corresponding java.util.DateFormat constant.
     *
     * @param style String description of formatting style for dates and times
     * @param errCode Error code to throw if given style is invalid
     *
     * @return java.util.DateFormat constant corresponding to given style
     *
     * @throws JspException if the given style is invalid
     */
    public static int getStyle(String style, String errCode) throws XpException {
        int ret = DateFormat.DEFAULT;

        if (style != null) {
            if (DEFAULT.equalsIgnoreCase(style)) {
                ret = DateFormat.DEFAULT;
            } else if (SHORT.equalsIgnoreCase(style)) {
                ret = DateFormat.SHORT;
            } else if (MEDIUM.equalsIgnoreCase(style)) {
                ret = DateFormat.MEDIUM;
            } else if (LONG.equalsIgnoreCase(style)) {
                ret = DateFormat.LONG;
            } else if (FULL.equalsIgnoreCase(style)) {
                ret = DateFormat.FULL;
            } else {
                throw new XpException("Invalid style " + errCode);
            }
        }

        return ret;
    }

    /**
     * HttpServletRequest.getLocales() returns the server's default locale if
     * the request did not specify a preferred language. We do not want this
     * behavior, because it prevents us from using the fallback locale. We
     * therefore need to return an empty Enumeration if no preferred locale has
     * been specified. This way, the logic for the fallback locale will be able
     * to kick in.
     */
    public static Enumeration getRequestLocales(HttpServletRequest request) {
        Enumeration values = request.getHeaders("accept-language");
        if (values.hasMoreElements()) {
            // At least one "accept-language". Simply return
            // the enumeration returned by request.getLocales().
            // System.out.println("At least one accept-language");
            return request.getLocales();
        } else {
            // No header for "accept-language". Simply return
            // the empty enumeration.
            // System.out.println("No accept-language");
            return values;
        }
    }
}