/*
* Copyright 2008 biaoping.yin
*
* 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.frameworkset.spi.support;
import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import org.apache.log4j.Logger;
/**
* <p>
* Title: MessageSourceSupport.java
* </p>
* <p>
* Description:
* </p>
* <p>
* bboss workgroup
* </p>
* <p>
* Copyright (c) 2007
* </p>
*
* @Date 2010-9-24 下午05:05:18
* @author biaoping.yin
* @version 1.0
*/
public abstract class MessageSourceSupport {
/** Logger available to subclasses */
protected static final Logger logger = Logger
.getLogger(MessageSourceSupport.class);
private boolean alwaysUseMessageFormat = false;
/**
* Cache to hold already generated MessageFormats per message. Used for
* passed-in default messages. MessageFormats for resolved codes are cached
* on a specific basis in subclasses.
*/
private final Map cachedMessageFormats = new HashMap();
/**
* Set whether to always apply the MessageFormat rules, parsing even
* messages without arguments.
* <p>
* Default is "false": Messages without arguments are by default returned
* as-is, without parsing them through MessageFormat. Set this to "true" to
* enforce MessageFormat for all messages, expecting all message texts to be
* written with MessageFormat escaping.
* <p>
* For example, MessageFormat expects a single quote to be escaped as "''".
* If your message texts are all written with such escaping, even when not
* defining argument placeholders, you need to set this flag to "true".
* Else, only message texts with actual arguments are supposed to be written
* with MessageFormat escaping.
*
* @see java.text.MessageFormat
*/
public void setAlwaysUseMessageFormat(boolean alwaysUseMessageFormat) {
this.alwaysUseMessageFormat = alwaysUseMessageFormat;
}
/**
* Return whether to always apply the MessageFormat rules, parsing even
* messages without arguments.
*/
protected boolean isAlwaysUseMessageFormat() {
return this.alwaysUseMessageFormat;
}
/**
* Format the given message String, using cached MessageFormats. By default
* invoked for passed-in default messages, to resolve any argument
* placeholders found in them.
*
* @param msg
* the message to format
* @param args
* array of arguments that will be filled in for params within
* the message, or <code>null</code> if none.
* @param locale
* the Locale used for formatting
* @return the formatted message (with resolved arguments)
*/
protected String formatMessage(String msg, Object[] args, Locale locale) {
if (msg == null
|| (!this.alwaysUseMessageFormat && (args == null || args.length == 0))) {
return msg;
}
MessageFormat messageFormat = (MessageFormat) this.cachedMessageFormats.get(msg);
if (messageFormat == null)
{
synchronized (this.cachedMessageFormats) {
messageFormat = (MessageFormat) this.cachedMessageFormats.get(msg);
if (messageFormat == null) {
messageFormat = createMessageFormat(msg, locale);
this.cachedMessageFormats.put(msg, messageFormat);
}
}
}
synchronized (messageFormat) {
return messageFormat.format(resolveArguments(args, locale));
}
}
/**
* Create a MessageFormat for the given message and Locale.
*
* @param msg
* the message to create a MessageFormat for
* @param locale
* the Locale to create a MessageFormat for
* @return the MessageFormat instance
*/
protected static MessageFormat createMessageFormat(String msg, Locale locale) {
if (logger.isDebugEnabled()) {
logger.debug("Creating MessageFormat for pattern [" + msg
+ "] and locale '" + locale + "'");
}
return new MessageFormat((msg != null ? msg : ""), locale);
}
/**
* Template method for resolving argument objects.
* <p>
* The default implementation simply returns the given argument array as-is.
* Can be overridden in subclasses in order to resolve special argument
* types.
*
* @param args
* the original argument array
* @param locale
* the Locale to resolve against
* @return the resolved argument array
*/
protected Object[] resolveArguments(Object[] args, Locale locale) {
return args;
}
/**
* Render the given default message String. The default message is passed in
* as specified by the caller and can be rendered into a fully formatted
* default message shown to the user.
* <p>
* The default implementation passes the String to
* <code>formatMessage</code>, resolving any argument placeholders found in
* them. Subclasses may override this method to plug in custom processing of
* default messages.
*
* @param defaultMessage
* the passed-in default message String
* @param args
* array of arguments that will be filled in for params within
* the message, or <code>null</code> if none.
* @param locale
* the Locale used for formatting
* @return the rendered default message (with resolved arguments)
* @see #formatMessage(String, Object[], java.util.Locale)
*/
protected String renderDefaultMessage(String defaultMessage, Object[] args,
Locale locale) {
return formatMessage(defaultMessage, args, locale);
}
}