Implementing Portlet Actions

Developing Your First Portlet

Step 7 of 8

When users submit the form, your application stores the form data for display in the guestbook. To keep this first application simple, you’ll implement this using a part of the Portlet API called Portlet Preferences. Normally, of course, you’d use a database, and you’ll refactor this into a database later. For now, however, you can create the first iteration of your guestbook application using portlet preferences.

To make your portlet do anything other than re-render itself, you must implement portlet actions. An action defines some processing, usually based on user input, that the portlet must perform before it renders itself. In the case of the guestbook portlet, the action you’ll implement next saves a guestbook entry that a user typed into the form. Saved guestbook entries can be retrieved and displayed later.

Since you’re using Liferay’s MVC Portlet framework, you have an easy way to implement actions. Portlet actions are implemented in the portlet class, which acts as the controller. In the form you just created, you made an action URL, and you called it addEntry. To create a portlet action, you create a method in the portlet class with the same name. MVCPortlet calls that method when a user triggers its matching URL.

  1. Open GuestbookPortlet. The project template generated this class when you created the portlet project.

  2. Create a method with the following signature:

    public void addEntry(ActionRequest request, ActionResponse response) {
    
    }
    
  3. Press [CTRL]+[SHIFT]+O to organize imports and import the required javax.portlet.ActionRequest and javax.portlet.ActionResponse classes.

You’ve now created a portlet action. It doesn’t do anything, but at least you won’t get an error now if you submit your form. Next, you should make the action save the form data.

Because of the limitations of the portlet preferences API, you must store each guestbook entry as a String in a string array. Since your form has two fields, you must use a delimiter to determine where the user name ends and the guestbook entry begins. The caret symbol (^) makes a good delimiter because users are highly unlikely to use that symbol in a guestbook entry.

The following method implements adding a guestbook entry to a portlet preference called guestbook-entries:

public void addEntry(ActionRequest request, ActionResponse response) {
    try {
        PortletPreferences prefs = request.getPreferences();

        String[] guestbookEntries = prefs.getValues("guestbook-entries",
                new String[1]);

        ArrayList<String> entries = new ArrayList<String>();

        if (guestbookEntries[0] != null) {
            entries = new ArrayList<String>(Arrays.asList(prefs.getValues(
                    "guestbook-entries", new String[1])));
        }

        String userName = ParamUtil.getString(request, "name");
        String message = ParamUtil.getString(request, "message");
        String entry = userName + "^" + message;

        entries.add(entry);

        String[] array = entries.toArray(new String[entries.size()]);

        prefs.setValues("guestbook-entries", array);

        try {
            prefs.store();
        }
        catch (IOException ex) {
            Logger.getLogger(GuestbookPortlet.class.getName()).log(
                    Level.SEVERE, null, ex);
        }
        catch (ValidatorException ex) {
            Logger.getLogger(GuestbookPortlet.class.getName()).log(
                    Level.SEVERE, null, ex);
        }

    }
    catch (ReadOnlyException ex) {
        Logger.getLogger(GuestbookPortlet.class.getName()).log(
                Level.SEVERE, null, ex);
    }
}
  1. Replace your existing addEntry method with the above method.

  2. Press [CTRL]+[SHIFT]+O to organize imports and select the javax.portlet.PortletPreferences, java.util.logging.Logger, and java.util.logging.Level when prompted (not their Liferay equivalents).

First, the preferences are retrieved. Then the guestbook-entries preference is retrieved and converted to an ArrayList so that you can add an entry without worrying about exceeding the size of the array. Next, the name and message fields from your form are retrieved. Notice how Liferay’s ParamUtil class makes it easy to retrieve URL parameters.

Finally, the fields are combined into a String delimited by a caret, and the new entry is added to the ArrayList, which is then converted back to an array so it can be stored as a preference. The try/catch blocks are required by the portlet preferences API.

This isn’t the normal way to use portlet preferences, but it provides a quick and easy way for you to store guestbook entries in this first version of your application. In a later step, you’ll implement a robust way to store guestbook entries in a database.

The next and final feature to implement is a mechanism for viewing guestbook entries.

« Creating a FormDisplaying Guestbook Entries »
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