Struts example source code file (TextProviderHelper.java)

This example Struts source code file (TextProviderHelper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

could, iterator, list, log, logger, object, string, string, textprovider, textprovider, the, the, util, valuestack, valuestack

The Struts TextProviderHelper.java source code

/*
 * $Id$
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.struts2.util;

import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import com.opensymphony.xwork2.TextProvider;

import java.util.Iterator;
import java.util.List;
import java.util.LinkedList;
import java.util.Collections;

/**
 * Helper methods to access text from TextProviders
 */
public class TextProviderHelper {

    private static final Logger LOG = LoggerFactory.getLogger(TextProviderHelper.class);

     /**
     * <p>Get a message from the first TextProvider encountered in the stack.
     * If the first TextProvider doesn't provide the message the default message is returned.</p>
     * The stack is searched if if no TextProvider is found, or the message is not found.
     * @param key             the message key in the resource bundle
     * @param defaultMessage  the message to return if not found (evaluated for OGNL)
     * @param args            an array args to be used in a {@link java.text.MessageFormat} message
     * @param stack           the value stack to use for finding the text
     *
     * @return the message if found, otherwise the defaultMessage
     */
    public static String getText(String key, String defaultMessage, List<Object> args, ValueStack stack) {
        return getText(key, defaultMessage, args, stack, true);
    }

    /**
     * <p>Get a message from the first TextProvider encountered in the stack.
     * If the first TextProvider doesn't provide the message the default message is returned.</p>
     * <p>The search for a TextProvider is iterative from the root of the stack.

     * <p>This method was refactored from  {@link org.apache.struts2.components.Text} to use a
     * consistent implementation across UIBean components.</p>
     * @param key             the message key in the resource bundle
     * @param defaultMessage  the message to return if not found (evaluated for OGNL)
     * @param args            an array args to be used in a {@link java.text.MessageFormat} message
     * @param stack           the value stack to use for finding the text
     * @param searchStack     search stack for the key
     *
     * @return the message if found, otherwise the defaultMessage
     */
    public static String getText(String key, String defaultMessage, List<Object> args, ValueStack stack, boolean searchStack) {
        String msg = null;
        TextProvider tp = null;

        for (Iterator iterator = stack.getRoot().iterator(); iterator.hasNext();) {
            Object o = iterator.next();

            if (o instanceof TextProvider) {
                tp = (TextProvider) o;
                msg = tp.getText(key, null, args, stack);

                break;
            }
        }

        if (msg == null) {
            // evaluate the defaultMesage as an OGNL expression
            if (searchStack)
                msg = stack.findString(defaultMessage);
            
            if (msg == null) {
                // use the defaultMessage literal value
                msg = defaultMessage;
            }

            if (LOG.isWarnEnabled()) {
                if (tp != null) {
                    LOG.warn("The first TextProvider in the ValueStack ("+tp.getClass().getName()+") could not locate the message resource with key '"+key+"'");
                } else {
                    LOG.warn("Could not locate the message resource '"+key+"' as there is no TextProvider in the ValueStack.");
                }
                if (msg.equals(defaultMessage)) {
                    LOG.warn("The default value expression '"+defaultMessage+"' was evaluated and did not match a property.  The literal value '"+defaultMessage+"' will be used.");
                } else {
                    LOG.warn("The default value expression '"+defaultMessage+"' evaluated to '"+msg+"'");
                }
            }
        }
        return msg;
    }

    /**
     * <p>Get a message from the first TextProvider encountered in the stack.
     * If the first TextProvider doesn't provide the message the default message is returned.</p>
     * <p>The search for a TextProvider is iterative from the root of the stack.

     * <p>This method was refactored from  {@link org.apache.struts2.components.Text} to use a
     * consistent implementation across UIBean components.</p>
     * @param key             the message key in the resource bundle
     * @param defaultMessage  the message to return if not found
     * @param stack           the value stack to use for finding the text
       *
     * @return the message if found, otherwise the defaultMessage
     */
    public static String getText(String key, String defaultMessage, ValueStack stack) {
        return getText(key, defaultMessage, Collections.emptyList(), stack);
    }
}