Using Liferay's Language Keys

Liferay specifies a host of language keys in its core Language.properties file. This file can be found in two different places. If you want to extract it from an existing runtime, you can find it in the content folder of your portal instance’s portal-impl.jar. This file is in the tomcat-[version]/webapps/ROOT/WEB-INF/lib directory of Liferay Portal bundled with Tomcat or the WEB-INF/lib folder of the Liferay .war file. If you want to get it from the Liferay source code, you can find it in portal-impl/src/content of your Liferay Portal source tree. Leveraging Portal’s core language keys saves you time, since these keys always have up to date translations for multiple languages. Additionally, your portlet blends better into Liferay’s UI conventions.

For this tutorial, you’ll implement a custom greeting for a portal user. When you’re finished with this tutorial, a user can view the following greeting in their custom portlet:

Figure 1: The portal user's name is used in the `welcome` language key.

Before you get started implementing our own language key, you’ll want to learn the components of a Liferay UI language key.

You can use a language key in your JSP via a <liferay-ui:message /> tag.

<liferay-ui:message key="message-key" />

You specify the message key corresponding to the language key in the Language.properties file you want to display. For example, to welcome a user in his or her language, specify the message key named welcome.

<liferay-ui:message key="welcome" />

This key maps to the word “Welcome” in your translation of it to the user’s locale. Here is the welcome language key from Liferay’s Language.properties file.

welcome=Welcome

Now that you know some basics, it’s time to implement the welcome language key for a custom portlet.

1. Open your portlet’s view.jsp file.

2. To use the welcome language key in the portlet’s UI, insert the following greeting paragraph:

    <p><liferay-ui:message key="welcome" />! <%= greeting %></p>
   

The word “Welcome”, from Language.properties, now precedes your greeting!

Note, in order to use the <liferay-ui:message /> tag, or any of the liferay-ui tags, you must include the following line in your JSP. It imports the liferay-ui tag library.

<%@ taglib uri="http://liferay.com/tld/ui" prefix="liferay-ui" %>

The <liferay-ui:message /> tag also supports passing strings as arguments to a language key. For example, the welcome-x key expects one argument. Here is the welcome-x key from the Language.properties file:

welcome-x=Welcome{0}!

It references {0}, which denotes the first argument of the argument list. An arbitrary number of arguments can be passed in via a message tag, but only those arguments expected by the language key are used. The arguments are referenced in order as {0}, {1}, etc. Given this information, you now know how to pass in the user’s screen name as an argument to the welcome-x language key in your portlet. You can compare your portlet’s view.jsp to the completed view.jsp for reference after you’ve completed the following steps.

1. Open the view.jsp file and add the following lines:

    <%@ taglib uri="http://liferay.com/tld/theme" prefix="liferay-theme"%>
   
    <liferay-theme:defineObjects />
   

   The first line imports the liferay-theme tag library. The second line defines the library’s objects, providing access to the user object holding the user’s screen name.

2. Replace the current welcome message tag and exclamation point, <liferay-ui:message key="welcome" />!, in the JSP with the following code:

    <liferay-ui:message key="welcome-x" arguments="<%= user.getScreenName() %>" />
   

Your portlet now greets you by your screen name!

Figure 2: By passing the user's screen name as an argument to Liferay's `welcome-x` language key, we're able to display a personalized greeting.

That’s all you need to do to leverage Liferay’s core localization keys. In this tutorial, you learned about Liferay core language keys, and how to implement in a Liferay portlet.

Related Topics:

Overriding Language Properties Using a Hook