4.2.10.1. Message Packs

A message pack is a set of properties files with the names in format of messages{_XX}.properties located in a single Java package. XX suffix indicates the language of the messages in this file and corresponds to the language code in Locale.getLanguage(). It is also possible to use other Locale attributes, for example, country. In this case the pack file will look like messages{_XX_YY}.properties. One of the files in the pack can have no language suffix – it is the default file. The name of the message pack corresponds to the name of the Java package, which contains the pack files.

Let us consider the following example:

/com/abc/sales/gui/customer/messages.properties
/com/abc/sales/gui/customer/messages_fr.properties
/com/abc/sales/gui/customer/messages_ru.properties

This pack consists of 3 files – one for Russian, one for French and a default file. The name of the pack is com.abc.sales.gui.customer.

Message files contain key/value pairs, where the key is the message identifier referenced by the application code, and the value is the message itself in the language of the file. The rules for matching pairs are similar to those of java.util.Properties properties files with the following specifics:

  • File encoding – UTF-8 only.

  • Including other message packs is supported using @include key. Several packs can be included using comma-separated enumeration. In this case, if some message key is found in both the current and the included pack, the message from the current pack will be used. Example of including packs:

    @include=com.haulmont.cuba.web, com.abc.sales.web

someMessage=Some Message
...

Messages are retrieved from the packs using Messages interface methods according to the following rules:

  • At first step search is performed in the application configuration directory.

    • messages_XX.properties file is searched in the directory specified by the message pack name, where XX is the code of the required language.

    • If there is no such file, default messages.properties file is searched in the same directory.

    • If either the required language file or the default file is found, it is loaded together with all @include files, and the key message is searched in it.

    • If the file is not found or it does not contain the proper key, the directory is changed to the parent one and the search procedure is repeated. The search continues until the root of the configuration directory is reached.

  • If the message is not found in the configuration directory, the search is performed in classpath according to the same algorithm.

  • On client tier, if the message is not found after the previous steps, the query is made to Middleware, and the message is searched there in the similar way.

  • If the message is found, it is cached and returned. If not, the fact that the message is not present is cached as well and the key which was passed for search is returned. Thus, the complex search procedure is only performed once and further on the result is loaded from the local cache of the application block.

Tip

It is recommended to organize message packs as follows:

  • If the application is not intended for internationalization, you can include message strings directly into the application code instead of using packs or use messages.properties default files to separate resources from code.

  • If the application is international, it is reasonable to use default files for the language of the application primary audience or for the English language, so that the messages from these default files are displayed to the user if the messages in the required language are not found.