Message Bundles
Description
Standard Java ResourceBundles have quite inefficient space characteristics.
Since a running Eclipse tends to have many externalized messages, we have implemented
a new message bundle system to be used in Eclipse. The mechanism is quite simple
and completely generic - it can be used anywhere.
Summary of the new approach:
-
messages.properties - this file is same as before except all
keys need to be valid Java identifiers.
- Each message file has a corresponding Java class.
- Each key/value pair in the file has a
public static String
field whose name is the same as the message key.
- When message bundles are loaded, the values of the fields are set to be
the values from the
messages.properties files.
- The message properties files are purged from memory.
When creating a new message:
- Create a field in your
Messages.java file.
- Create a key/value pair in your
messages.properties file where
the key name matches the field name,
- To reference the message, simply reference the field (e.g.
Messages.my_key)
rather than the standard lookup.
Example Files:
Client Code
Old Code:
public class MyClass {
public void myMethod() {
String message;
...
// no args
message = Messages.getString("key.one"); //$NON-NLS-1$
...
// bind one arg
message = MessageFormat.format(Messages.getString("key.two"), new Object[] {"example usage"}); //$NON-NLS-1$ //$NON-NLS-2$
...
}
}
New Code:
public class MyClass {
public void myMethod() {
String message;
...
// no args
message = Messages.key_one;
...
// bind one arg
message = NLS.bind(Messages.key_two, "example usage"); //$NON-NLS-1$
...
}
}
Messages.java
Old Code:
public class Messages {
private static final String BUNDLE_NAME = "org.eclipse.core.utils.messages"; //$NON-NLS-1$
private static final ResourceBundle bundle = ResourceBundle.getBundle(BUNDLE_NAME);
public static String getString(String key) {
try {
return bundle.getString(key);
} catch (MissingResourceException e) {
return key;
}
}
}
New Code:
import org.eclipse.osgi.util.NLS;
public class Messages extends NLS {
private static final String BUNDLE_NAME = "org.eclipse.core.utils.messages"; //$NON-NLS-1$
public static String key_one;
public static String key_two;
...
static {
NLS.initializeMessages(BUNDLE_NAME, Messages.class);
}
}
messages.properties
Old Code:
key.one = Hello world.
key.two = This is an {0} of binding with one argument.
New Code:
key_one = Hello world.
key_two = This is an {0} of binding with one argument.
