Jakarta Struts Cookbook

12.1. Detecting Browser Language Settings

Problem

Your web application needs to support the language settings of the client's browser.

Solution

If you are using the default settings of Struts, you don't have to do anything; the browser's locale will be automatically detected.

Discussion

When a request is routed through the Struts RequestProcessor, the processLocale() method is called. Example 12-1 shows the implementation of this method in the RequestProcessor from Struts 1.2.

Example 12-1. How the RequestProcessor sets the locale

/**
 * <p>Automatically select a <code>Locale</code> for the current user, 
 * if requested.
 * <strong>NOTE</strong> - configuring Locale selection will trigger
 * the creation of a new <code>HttpSession</code> if necessary.</p>
 *
 * @param request The servlet request we are processing
 * @param response The servlet response we are creating
 */
protected void processLocale(HttpServletRequest request,
                             HttpServletResponse response) {

    // Are we configured to select the Locale automatically?
    if (!moduleConfig.getControllerConfig( ).getLocale( )) {
        return;
    }

    // Has a Locale already been selected?
    HttpSession session = request.getSession( );
    if (session.getAttribute(Globals.LOCALE_KEY) != null) {
        return;
    }

    // Use the Locale returned by the servlet container (if any)
    Locale locale = request.getLocale( );
    if (locale != null) {
        if (log.isDebugEnabled( )) {
            log.debug(" Setting user locale '" + locale + "'");
        }
        session.setAttribute(Globals.LOCALE_KEY, locale);
    }

}

The method first ...