MessageFormat
* class to produce internationalized messages with parametric replacement.
*
* Calls to getMessage() variants without a Locale
* argument are presumed to be requesting a message string in the default
* Locale for this JVM.
*
* Calls to getMessage() with an unknown key, or an unknown
* Locale will return null if the
* returnNull property is set to true. Otherwise,
* a suitable error message will be returned instead.
*
* IMPLEMENTATION NOTE - Classes that extend this class
* must be Serializable so that instances may be used in distributable
* application server environments.
*
* @author Craig R. McClanahan
* @version $Revision: 1.16 $ $Date: 2002/11/09 04:04:11 $
*/
public abstract class MessageResources implements Serializable {
// ------------------------------------------------------------- Properties
/**
* Commons Logging instance.
*/
protected static Log log = LogFactory.getLog(MessageResources.class);
/**
* The configuration parameter used to initialize this MessageResources.
*/
protected String config = null;
/**
* The configuration parameter used to initialize this MessageResources.
* @return parameter used to initialize this MessageResources
*/
public String getConfig() {
return (this.config);
}
/**
* The default Locale for our environment.
*/
protected Locale defaultLocale = Locale.getDefault();
/**
* The MessageResourcesFactory that created this instance.
*/
protected MessageResourcesFactory factory = null;
/**
* The MessageResourcesFactory that created this instance.
* @return MessageResourcesFactory that created instance
*/
public MessageResourcesFactory getFactory() {
return (this.factory);
}
/**
* The set of previously created MessageFormat objects, keyed by the
* key computed in messageKey().
*/
protected HashMap formats = new HashMap();
/**
* Indicate is a null is returned instead of an error message string
* when an unknown Locale or key is requested.
*/
protected boolean returnNull = false;
/**
* Indicates that a null 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 null is returned instead of an error message string
* if an unknown Locale or key is requested.
* @param returnNull true Indicates that a null is returned
* if an unknown Locale or key is requested.
*/
public void setReturnNull(boolean returnNull) {
this.returnNull = returnNull;
}
// ----------------------------------------------------------- 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;
}
// --------------------------------------------------------- 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 (getMessage((Locale) null, key));
}
/**
* 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 (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 (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 (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 (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
*/
public String getMessage(String key, Object arg0, Object arg1,
Object arg2, Object arg3) {
return (getMessage((Locale) null, key, arg0, arg1, arg2, arg3));
}
/**
* Returns a text message for the specified key, for the default Locale.
* A null string result will be returned by this method if no relevant
* message resource is found for this key or Locale, if the
* returnNull property is set. Otherwise, an appropriate
* error message will be returned.
*
* This method must be implemented by a concrete subclass.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @param key The message key to look up
*/
public abstract String getMessage(Locale locale, String key);
/**
* Returns a text message after parametric replacement of the specified
* parameter placeholders. A null string result will be returned by
* this method if no resource bundle has been configured.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @param key The message key to look up
* @param args An array of replacement parameters for placeholders
*/
public String getMessage(Locale locale, String key, Object args[]) {
// Cache MessageFormat instances as they are accessed
if (locale == null)
locale = defaultLocale;
MessageFormat format = null;
String formatKey = messageKey(locale, key);
synchronized (formats) {
format = (MessageFormat) formats.get(formatKey);
if (format == null) {
String formatString = getMessage(locale, key);
if (formatString == null) {
if (returnNull)
return (null);
else
return ("???" + formatKey + "???");
}
format = new MessageFormat(escape(formatString));
formats.put(formatKey, format);
}
}
return (format.format(args));
}
/**
* Returns a text message after parametric replacement of the specified
* parameter placeholders. A null string result will never be returned
* by this method.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @param key The message key to look up
* @param arg0 The replacement for placeholder {0} in the message
*/
public String getMessage(Locale locale, String key, Object arg0) {
Object args[] = new Object[1];
args[0] = arg0;
return (getMessage(locale, key, args));
}
/**
* Returns a text message after parametric replacement of the specified
* parameter placeholders. A null string result will never be returned
* by this method.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @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(Locale locale,
String key, Object arg0, Object arg1) {
Object args[] = new Object[2];
args[0] = arg0;
args[1] = arg1;
return (getMessage(locale, key, args));
}
/**
* Returns a text message after parametric replacement of the specified
* parameter placeholders. A null string result will never be returned
* by this method.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @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(Locale locale,
String key, Object arg0, Object arg1,
Object arg2) {
Object args[] = new Object[3];
args[0] = arg0;
args[1] = arg1;
args[2] = arg2;
return (getMessage(locale, key, args));
}
/**
* Returns a text message after parametric replacement of the specified
* parameter placeholders. A null string result will never be returned
* by this method.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @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
*/
public String getMessage(Locale locale,
String key, Object arg0, Object arg1,
Object arg2, Object arg3) {
Object args[] = new Object[4];
args[0] = arg0;
args[1] = arg1;
args[2] = arg2;
args[3] = arg3;
return (getMessage(locale, key, args));
}
/**
* Return true if there is a defined message for the specified
* key in the system default locale.
*
* @param key The message key to look up
*/
public boolean isPresent(String key) {
return (isPresent(null, key));
}
/**
* Return true if there is a defined message for the specified
* key in the specified Locale.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @param key The message key to look up
*/
public boolean isPresent(Locale locale, String key) {
String message = getMessage(locale, key);
if (message == null)
return (false);
else if (message.startsWith("???") && message.endsWith("???"))
return (false); // FIXME - Only valid for default implementation
else
return (true);
}
// ------------------------------------------------------ Protected Methods
/**
* Escape any single quote characters that are included in the specified
* message string.
*
* @param string The string to be escaped
*/
protected String escape(String string) {
if ((string == null) || (string.indexOf('\'') < 0))
return (string);
int n = string.length();
StringBuffer sb = new StringBuffer(n);
for (int i = 0; i < n; i++) {
char ch = string.charAt(i);
if (ch == '\'')
sb.append('\'');
sb.append(ch);
}
return (sb.toString());
}
/**
* Compute and return a key to be used in caching information by a Locale.
* NOTE - The locale key for the default Locale in our
* environment is a zero length String.
*
* @param locale The locale for which a key is desired
*/
protected String localeKey(Locale locale) {
if (locale == null)
return ("");
// else if (locale.equals(defaultLocale))
// return ("");
else
return (locale.toString());
}
/**
* Compute and return a key to be used in caching information
* by Locale and message key.
*
* @param locale The Locale for which this format key is calculated
* @param key The message key for which this format key is calculated
*/
protected String messageKey(Locale locale, String key) {
return (localeKey(locale) + "." + key);
}
/**
* Compute and return a key to be used in caching information
* by locale key and message key.
*
* @param localeKey The locale key for which this cache key is calculated
* @param key The message key for which this cache key is calculated
*/
protected String messageKey(String localeKey, String key) {
return (localeKey + "." + key);
}
// --------------------------------------------------------- Static Methods
/**
* The default MessageResourcesFactory used to create MessageResources
* instances.
*/
protected static MessageResourcesFactory defaultFactory = null;
/**
* Create and return an instance of MessageResources for the
* created by the default MessageResourcesFactory.
*
* @param config Configuration parameter for this message bundle.
*/
public synchronized static MessageResources
getMessageResources(String config) {
if (defaultFactory == null)
defaultFactory = MessageResourcesFactory.createFactory();
return defaultFactory.createResources(config);
}
/**
* Log a message to the Writer that has been configured for our use.
*
* @param message The message to be logged
*/
public void log(String message) {
log.debug(message);
}
/**
* Log a message and exception to the Writer that has been configured
* for our use.
*
* @param message The message to be logged
* @param throwable The exception to be logged
*/
public void log(String message, Throwable throwable) {
log.debug(message, throwable);
}
}