messageresources.java.svn-base

MVC开源框架

/*
 * $Id$
 *
 * 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.struts.util;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.Serializable;

import java.text.MessageFormat;

import java.util.HashMap;
import java.util.Locale;

/**
 * General purpose abstract class that describes an API for retrieving
 * Locale-sensitive messages from underlying resource locations of an
 * unspecified design, and optionally utilizing the <code>MessageFormat</code>
 * class to produce internationalized messages with parametric replacement.
 * <p> Calls to <code>getMessage()</code> variants without a
 * <code>Locale</code> argument are presumed to be requesting a message string
 * in the default <code>Locale</code> for this JVM. <p> Calls to
 * <code>getMessage()</code> with an unknown key, or an unknown
 * <code>Locale</code> will return <code>null</code> if the
 * <code>returnNull</code> property is set to <code>true</code>.  Otherwise, a
 * suitable error message will be returned instead. <p> <strong>IMPLEMENTATION
 * NOTE</strong> - Classes that extend this class must be Serializable so that
 * instances may be used in distributable application server environments.
 *
 * @version $Rev$ $Date: 2005-08-29 23:57:50 -0400 (Mon, 29 Aug 2005)
 *          $
 */
public abstract class MessageResources implements Serializable {
    // ------------------------------------------------------------- Properties

    /**
     * Commons Logging instance.
     */
    protected static Log log = LogFactory.getLog(MessageResources.class);

    // --------------------------------------------------------- Static Methods

    /**
     * The default MessageResourcesFactory used to create MessageResources
     * instances.
     */
    protected static MessageResourcesFactory defaultFactory = null;

    /**
     * The configuration parameter used to initialize this MessageResources.
     */
    protected String config = null;

    /**
     * The default Locale for our environment.
     */
    protected Locale defaultLocale = Locale.getDefault();

    /**
     * The <code>MessageResourcesFactory</code> that created this instance.
     */
    protected MessageResourcesFactory factory = null;

    /**
     * The set of previously created MessageFormat objects, keyed by the key
     * computed in <code>messageKey()</code>.
     */
    protected HashMap formats = new HashMap();

    /**
     * Indicate is a <code>null</code> is returned instead of an error message
     * string when an unknown Locale or key is requested.
     */
    protected boolean returnNull = false;

    /**
     * Indicates whether 'escape processing' should be performed on the error
     * message string.
     */
    private boolean escape = true;

    // ----------------------------------------------------------- Constructors

    /**
     * Construct a new MessageResources according to the specified
     * parameters.
     *
     * @param factory The MessageResourcesFactory that created us
     * @param config  The configuration parameter for this MessageResources
     */
    public MessageResources(MessageResourcesFactory factory, String config) {
        this(factory, config, false);
    }

    /**
     * Construct a new MessageResources according to the specified
     * parameters.
     *
     * @param factory    The MessageResourcesFactory that created us
     * @param config     The configuration parameter for this
     *                   MessageResources
     * @param returnNull The returnNull property we should initialize with
     */
    public MessageResources(MessageResourcesFactory factory, String config,
        boolean returnNull) {
        super();
        this.factory = factory;
        this.config = config;
        this.returnNull = returnNull;
    }

    /**
     * The configuration parameter used to initialize this MessageResources.
     *
     * @return parameter used to initialize this MessageResources
     */
    public String getConfig() {
        return (this.config);
    }

    /**
     * The <code>MessageResourcesFactory</code> that created this instance.
     *
     * @return <code>MessageResourcesFactory</code> that created instance
     */
    public MessageResourcesFactory getFactory() {
        return (this.factory);
    }

    /**
     * Indicates that a <code>null</code> is returned instead of an error
     * message string if an unknown Locale or key is requested.
     *
     * @return true if null is returned if unknown key or locale is requested
     */
    public boolean getReturnNull() {
        return (this.returnNull);
    }

    /**
     * Indicates that a <code>null</code> is returned instead of an error
     * message string if an unknown Locale or key is requested.
     *
     * @param returnNull true Indicates that a <code>null</code> is returned
     *                   if an unknown Locale or key is requested.
     */
    public void setReturnNull(boolean returnNull) {
        this.returnNull = returnNull;
    }

    /**
     * Indicates whether 'escape processing' should be performed on the error
     * message string.
     *
     * @since Struts 1.2.8
     */
    public boolean isEscape() {
        return escape;
    }

    /**
     * Set whether 'escape processing' should be performed on the error
     * message string.
     *
     * @since Struts 1.2.8
     */
    public void setEscape(boolean escape) {
        this.escape = escape;
    }

    // --------------------------------------------------------- Public Methods

    /**
     * Returns a text message for the specified key, for the default Locale.
     *
     * @param key The message key to look up
     */
    public String getMessage(String key) {
        return this.getMessage((Locale) null, key, null);
    }

    /**
     * Returns a text message after parametric replacement of the specified
     * parameter placeholders.
     *
     * @param key  The message key to look up
     * @param args An array of replacement parameters for placeholders
     */
    public String getMessage(String key, Object[] args) {
        return this.getMessage((Locale) null, key, args);
    }

    /**
     * Returns a text message after parametric replacement of the specified
     * parameter placeholders.
     *
     * @param key  The message key to look up
     * @param arg0 The replacement for placeholder {0} in the message
     */
    public String getMessage(String key, Object arg0) {
        return this.getMessage((Locale) null, key, arg0);
    }

    /**
     * Returns a text message after parametric replacement of the specified
     * parameter placeholders.
     *
     * @param key  The message key to look up
     * @param arg0 The replacement for placeholder {0} in the message
     * @param arg1 The replacement for placeholder {1} in the message
     */
    public String getMessage(String key, Object arg0, Object arg1) {
        return this.getMessage((Locale) null, key, arg0, arg1);
    }

    /**
     * Returns a text message after parametric replacement of the specified
     * parameter placeholders.
     *
     * @param key  The message key to look up
     * @param arg0 The replacement for placeholder {0} in the message
     * @param arg1 The replacement for placeholder {1} in the message
     * @param arg2 The replacement for placeholder {2} in the message
     */
    public String getMessage(String key, Object arg0, Object arg1, Object arg2) {
        return this.getMessage((Locale) null, key, arg0, arg1, arg2);
    }

    /**
     * Returns a text message after parametric replacement of the specified
     * parameter placeholders.
     *
     * @param key  The message key to look up
     * @param arg0 The replacement for placeholder {0} in the message
     * @param arg1 The replacement for placeholder {1} in the message
     * @param arg2 The replacement for placeholder {2} in the message
     * @param arg3 The replacement for placeholder {3} in the message
     */